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  • 151.
    Lindqvist, Per
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences.
    Right ventricular outflow-tract fractional shortening: an applicable measure of right ventricular systolic function.2003In: European Journal of Echocardiography, ISSN 1525-2167, E-ISSN 1532-2114Article in journal (Refereed)
  • 152.
    Lindqvist, Per
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    Mörner, Stellan
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    Henein, Michael Y
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    Cardiac mechanisms underlying normal exercise tolerance: gender impact2012In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 112, no 2, p. 451-459Article in journal (Refereed)
    Abstract [en]

    The aim of this study is to test our hypothesis that normal exercise tolerance differs according to gender and to identify potential functional cardiac relationships, which could explain those differences. A total of 44 healthy individuals with mean age of 49 ± 12 years (28-74 years, 22 males) constituted the study cohort. All individuals underwent resting and exercise Doppler echocardiogram simultaneously with peak oxygen uptake analysis (pVO(2)). At equal pVO(2), males achieved higher peak exercise workload (p < 0.001) and females higher heart rate (p < 0.001) but the two groups maintained similar indexed left ventricular (LV) stroke volume (SV) and cardiac output. Indexed LV end-diastolic (LVDVI) and end-systolic volumes (LVSVI) were smaller in females (p < 0.001 and p < 0.01, respectively), but filling time (FT) was shorter (p < 0.001) and they had higher early diastolic (E) velocity (p = 0.004), E/E (m) (myocardial E velocity) (p < 0.001) and global longitudinal strain rate atrial velocity (GLSRa') (p = 0.02), compared to males. In males, workload (p < 0.01), LVDVI (p < 0.01), LVSVI (p < 0.05), SVI (p < 0.001) directly but LV myocardial isovolumic relaxation time (IVRTm) (p < 0.01) inversely correlated with pVO(2). In females, mitral E velocity (p < 0.01), GLSRs' (p < 0.05) positively and LVFT negatively (p < 0.05) correlated with pVO(2). In a multivariable analysis SVI in males (p < 0.01) and GLSRs' in females (p < 0.01) were the strongest predictors for pVO(2). Thus, normal exercise capacity as determined by pVO(2) is related to the indexed stroke volume in males and left atrial pressure in females. These native normal differences between genders may explain the known vulnerability of women to endurance exercise compared to men.

  • 153. Lorås, H
    et al.
    Sigmundsson, H
    Talcott, JB
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Stensdotter, AK
    Timing continuous or discontinuous movements across effectors specified by different pacing modalities and intervals2012In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 220, no 3-4, p. 335-347Article in journal (Refereed)
    Abstract [en]

    Sensorimotor synchronization is hypothesized to arise through two different processes, associated with continuous or discontinuous rhythmic movements. This study investigated synchronization of continuous and discontinuous movements to different pacing signals (auditory or visual), pacing interval (500, 650, 800, 950 ms) and across effectors (non-dominant vs. non-dominant hand). The results showed that mean and variability of asynchronization errors were consistently smaller for discontinuous movements compared to continuous movements. Furthermore, both movement types were timed more accurately with auditory pacing compared to visual pacing and were more accurate with the dominant hand. Shortening the pacing interval also improved sensorimotor synchronization accuracy in both continuous and discontinuous movements. These results show the dependency of temporal control of movements on the nature of the motor task, the type and rate of extrinsic sensory information as well as the efficiency of the motor actuators for sensory integration.

  • 154. Lorås, Håvard
    et al.
    Stensdotter, Ann-Katrin
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Sigmundsson, Hermundur
    Individual differences in motor timing and its relation to cognitive and fine motor skills2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 7, p. e69353-Article in journal (Refereed)
  • 155.
    Lucas, Rebekah A. I.
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health. Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, TX ; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX.
    Pearson, James
    Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, TX ; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX ; Cardiff Metropolitan University, Cardiff, Wales.
    Schlader, Zachary J.
    Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, TX ; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX.
    Crandall, Craig G.
    Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, TX ; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX.
    Hypercapnia-induced increases in cerebral blood flow do not improve lower body negative pressure tolerance during hyperthermia2013In: American Journal of Physiology. Regulatory Integrative and Comparative Physiology, ISSN 0363-6119, E-ISSN 1522-1490, Vol. 305, no 6, p. R604-R609Article in journal (Refereed)
    Abstract [en]

    Heat-related decreases in cerebral perfusion are partly the result of ventilatory-related reductions in arterial CO2 tension. Cerebral perfusion likely contributes to an individual's tolerance to a challenge like lower body negative pressure (LBNP). Thus increasing cerebral perfusion may prolong LBNP tolerance. This study tested the hypothesis that a hypercapnia-induced increase in cerebral perfusion improves LBNP tolerance in hyperthermic individuals. Eleven individuals (31 +/- 7 yr; 75 +/- 12 kg) underwent passive heat stress (increased intestinal temperature similar to 1.3 degrees C) followed by a progressive LBNP challenge to tolerance on two separate days (randomized). From 30 mmHg LBNP, subjects inhaled either (blinded) a hypercapnic gas mixture (5% CO2, 21% oxygen, balanced nitrogen) or room air (SHAM). LBNP tolerance was quantified via the cumulative stress index (CSI). Mean middle cerebral artery blood velocity (MCAv(mean),) and end-tidal CO2 (PETCO2) were also measured. CO2 inhalation of 5% increased PETCO2 at similar to 40 mmHg LBNP (by 16 +/- 4 mmHg) and at LBNP tolerance (by 18 +/- 5 mmHg) compared with SHAM (P < 0.01). Subsequently, MCAvmean was higher in the 5% CO2 trial during similar to 40 mmHg LBNP (by 21 +/- 12 cm/s, similar to 31%) and at LBNP tolerance (by 18 +/- 10 cm/s, similar to 25%) relative to the SHAM (P < 0.01). However, hypercapnia-induced increases in MCAvmean did not alter LBNP tolerance (5% CO2 CSI: 339 +/- 155 mmHg X min; SHAM CSI: 273 +/- 158 mmHg X min; P = 0.26). These data indicate that inhaling a hypercapnic gas mixture increases cerebral perfusion during LBNP but does not improve LBNP tolerance when hyperthermic.

  • 156.
    Lund, James P
    et al.
    Université de Montréal.
    Sadeghi, Somayeh
    McGill University, Montréal.
    Athanassiadis, Tuija
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Caram Salas, Nadia
    McGill University, Montréal.
    Auclair, François
    Université de Montréal.
    Thivierge, Benoît
    Université de Montréal.
    Arsenault, Isabel
    Université de Montréal.
    Rompré, Pierre
    Université de Montréal.
    Westberg, Karl-Gunnar
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Kolta, Arlette
    Université de Montréal, McGill University, Montréal.
    Assessment of the potential role of muscle spindle mechanoreceptor afferents in chronic muscle pain in the rat masseter muscle2010In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 5, no 6, p. e11131-Article in journal (Refereed)
    Abstract [en]

    Low pH leads to changes in several electrical properties of MSA, including initiation of ectopic action potentials which could propagate centrally but could also invade the peripheral endings causing glutamate release and activation of nearby nociceptors within the spindle capsule. This peripheral drive could contribute both to the transition to, and maintenance of, persistent muscle pain as seen in some "functional" pain syndromes.

  • 157.
    Macefield, Vaughan G
    et al.
    Prince of Wales Medical Research Institute, UNSW, Barker St., Randwick, Sydney.
    Johansson, Roland S
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Loads applied tangential to a fingertip during an object restraint task can trigger short-latency as well as long-latency EMG responses in hand muscles.2003In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 152, no 2, p. 143-149Article in journal (Refereed)
    Abstract [en]

    Electrical stimulation of the digital nerves can cause short- and long-latency increases in electromyographic activity (EMG) of the hand muscles, but mechanical stimulation of primarily tactile afferents in the digits generally evokes only a long-latency increase in EMG. To examine whether such stimuli can elicit short-latency reflex responses, we recorded EMG over the first dorsal interosseous muscle when subjects (n=13) used the tip of the right index finger to restrain a horizontally oriented plate from moving when very brisk tangential forces were applied in the distal direction. The plate was subjected to ramp-and-hold pulling loads at two intensities (a 1-N load applied at 32 N/s or a 2-N load applied at 64 N/s) at times unpredictable to the subjects (mean interval 2 s; trial duration 500 ms). The contact surface of the manipulandum was covered with rayon--a slippery material. For each load, EMG was averaged for 128 consecutive trials with reference to the ramp onset. In all subjects, an automatic increase in grip force was triggered by the loads applied at 32 N/s; the mean onset latency of the EMG response was 59.8 +/- 0.9 (mean +/- SE) ms. In seven subjects (54%) this long-latency response was preceded by a weak short-latency excitation at 34.6 +/- 2.9 ms. With the loads applied at 64 N/s, the long-latency response occurred slightly earlier (58.9 +/- 1.7 ms) and, with one exception, all subjects generated a short-latency EMG response (34.9 +/- 1.3 ms). Despite the higher background grip force that subjects adopted during the stronger loads (4.9 +/- 0.3 N vs 2.5 +/- 0.2 N), the incidence of slips was higher--the manipulandum escaped from the grasp in 37 +/- 5% of trials with the 64 N/s ramps, but in only 18 +/- 4% with the 32-N/s ramps. The deformation of the fingertip caused by the tangential load, rather than incipient or overt slips, triggered the short-latency responses because such responses occurred even when the finger pad was fixed to the manipulandum with double-sided adhesive tape so that no slips occurred.

  • 158.
    Madison, Guy
    et al.
    Department of Psychology, Uppsala University, Box 1225, SE-75142 Uppsala, Sweden.
    Merker, Björn
    Department of Psychology, Uppsala University, Box 1225, SE-75142 Uppsala, Sweden.
    Human sensorimotor tracking of continuous subliminal deviations from isochrony2004In: Neuroscience Letters, ISSN 0304-3940, Vol. 370, p. 69-73Article in journal (Refereed)
    Abstract [en]

    We show that people continuously react to time perturbations in the range 3-96 ms in otherwise isochronous sound sequences. Musically trained and untrained participants were asked to synchronize with a sequence of sounds, and these two groups performed almost equally below the threshold for conscious detection of the deviations. Above this threshold the motor reactions accounted for a larger proportion of the stimulus deviations for musically trained participants.

  • 159. Maeda, Rodrigo S.
    et al.
    Cluff, Tyler
    Gribble, Paul L.
    Pruszynski, J. Andrew
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Brain and Mind Institute, Western University, London, Ontario, Canada; Robarts Research Institute, Western University, London, Ontario, Canada; Department of Psychology, Western University, London, Ontario, Canada; Department of Physiology and Pharmacology, Western University, London, Ontario, Canada.
    Compensating for intersegmental dynamics across the shoulder, elbow, and wrist joints during feedforward and feedback control2017In: Journal of Neurophysiology, ISSN 0022-3077, E-ISSN 1522-1598, Vol. 118, no 4, p. 1984-1997Article in journal (Refereed)
    Abstract [en]

    Moving the arm is complicated by mechanical interactions that arise between limb segments. Such intersegmental dynamics cause torques applied at one joint to produce movement at multiple joints, and in turn, the only way to create single joint movement is by applying torques at multiple joints. We investigated whether the nervous system accounts for intersegmental limb dynamics across the shoulder, elbow, and wrist joints during self-initiated planar reaching and when countering external mechanical perturbations. Our first experiment tested whether the timing and amplitude of shoulder muscle activity account for interaction torques produced during single-joint elbow movements from different elbow initial orientations and over a range of movement speeds. We found that shoulder muscle activity reliably preceded movement onset and elbow agonist activity, and was scaled to compensate for the magnitude of interaction torques arising because of forearm rotation. Our second experiment tested whether elbow muscles compensate for interaction torques introduced by single-joint wrist movements. We found that elbow muscle activity preceded movement onset and wrist agonist muscle activity, and thus the nervous system predicted interaction torques arising because of hand rotation. Our third and fourth experiments tested whether shoulder muscles compensate for interaction torques introduced by different hand orientations during self-initiated elbow movements and to counter mechanical perturbations that caused pure elbow motion. We found that the nervous system predicted the amplitude and direction of interaction torques, appropriately scaling the amplitude of shoulder muscle activity during self-initiated elbow movements and rapid feedback control. Taken together, our results demonstrate that the nervous system robustly accounts for intersegmental dynamics and that the process is similar across the proximal to distal musculature of the arm as well as between feedforward (i.e., self- initiated) and feedback (i.e., reflexive) control. NEW & NOTEWORTHY Intersegmental dynamics complicate the mapping between applied joint torques and the resulting joint motions. We provide evidence that the nervous system robustly predicts these intersegmental limb dynamics across the shoulder, elbow, and wrist joints during reaching and when countering external perturbations.

  • 160. Magnusson, Beatrice M.
    et al.
    Koskinen, Lars-Owe D.
    National Defense Research Establishment, Department of NBC Defence, Division of Biomedicine and Department of Neurosurgery, University Hospital of Northern Sween, Umeå, Sweden .
    Effects of topical application of capsaicin to human skin: a comparison of effects evaluated by visual assessment, sensation registration, skin blood flow and cutaneous impedance measurements.1996In: Acta Dermato-Venereologica, ISSN 0001-5555, E-ISSN 1651-2057, Vol. 76, no 2, p. 129-132Article in journal (Refereed)
    Abstract [en]

    A new non-invasive device, which enables local measurements of electrical impedance, has been used to evaluate the degree of irritation in human skin. The results have been compared with visual scoring, sensations and laser Doppler flowmetry. Capsaicin (50 microliters 1% solution) and control solutions (50 microliters 50% ethanol) were applied in a chamber for 30 min on the volar forearm of 7 volunteers. Values were recorded before application and during the total test period of 4.5 h. Sensations like sting/prick, burn and pain were produced by this treatment, and the flare response was observed. Using the non-invasive laser Doppler flow technique to measure blood flow in human skin, we have shown that topical application of capsaicin abolishes the vasodilator response to local heat provocation (40 degrees C). There was close agreement among values obtained using visual assessments, sensations and laser Doppler flowmetry. Results obtained using electrical impedance measurements were not consistent with the other three methods.

  • 161. Magnusson, Beatrice M.
    et al.
    Runn, Per
    Koskinen, Lars-Owe D.
    National Defense Research Establishment, Department of NBC Defence, Division of Biomedicine and Department of Neurosurgery, University Hospital of Northern Sween, Umeå, Sweden.
    Terpene-enhanced transdermal permeation of water and ethanol in human epidermis.1997In: Acta Dermato-Venereologica, ISSN 0001-5555, E-ISSN 1651-2057, Vol. 77, no 4, p. 264-267Article in journal (Refereed)
    Abstract [en]

    The study was performed to investigate the effect of penetration enhancers on the stratum corneum barrier. Epidermal membranes were prepared from freeze-stored (-70 degrees C) Caucasian breast skin and mounted in a flow-through diffusion cell. The validity of the freeze storage procedure was verified by measurement of [3H]-water penetration. The effect of the cyclic terpene, carveol, on the transdermal penetration of water and ethanol was studied in vitro. Control ethanol and water penetration measured with a donor solution of 50% ethanol/PBS (w/w) was 1.9+/-0.2 and 3.6+/-0.5 x 10(-3) cm/h. The addition of 3% carveol to the donor solution increased the permeation of ethanol and water after 4 h to 8.3+/-1.1 and 12.5+/-1.9 x 10(-3) cm/h, respectively. In a separate experiment, terpinen-4-ol and alpha-terpineol were also tested, in addition to carveol, for effect on tritium flux. No significant difference in maximum tritium flux was obtained between the three terpenes studied. The maximum increase in permeability coefficients of carveol, terpinen-4-ol and alpha-terpineol was 10.6, 8.7 and 10.9, respectively.

  • 162.
    Malinina, Evgenya
    Umeå University, Faculty of Medicine, Integrative Medical Biology, Physiology.
    Neurotransmission and functional synaptic plasticity in the rat medial preoptic nucleus2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Brain function implies complex information processing in neuronal circuits, critically dependent on the molecular machinery that enables signal transmission across synaptic contacts between neurons. The types of ion channels and receptors in the neuronal membranes vary with neuron types and brain regions and determine whether neuronal responses will be excitatory or inhibitory and often allow for functional synaptic plasticity which is thought to be the basis for much of the adaptability of the nervous system and for our ability to learn and store memories. The present thesis is a study of synaptic transmission in the medial preoptic nucleus (MPN), a regulatory center for several homeostatic functions but with most clearly established roles in reproductive behaviour. The latter behaviour typically shows several distinct phases with dramatically varying neuronal impulse activity and is also subject to experience-dependent modifications. It seems likely that the synapses in the MPN contribute to the behaviour by means of activity-dependent functional plasticity. Synaptic transmission in the MPN, however, has not been extensively studied and is not well understood. The present work was initiated to clarify the synaptic properties in the MPN. The aim was to achieve a better understanding of the functional properties of the MPN, but also to obtain information on the functional roles of ion channel types for neurotransmission and its plastic properties in general. The studies were carried out using a brain slice preparation from rat as well as acutely isolated neurons with adhering nerve terminals. Presynaptic nerve fibres were stimulated electrically or, in a few cases, by raised external K+ concentration, and postsynaptic responses were recorded by tight-seal perforated-patch techniques, often combined with voltage-clamp control of the post-synaptic membrane potential. Glutamate receptors of α-amino-3-hydroxy-5-methyl-4-izoxazole propionic acid (AMPA) and N-methyl-D-aspartate (NMDA) types were identified as mediating the main excitatory synaptic signals and γ-aminobutyric acid (GABA)A receptors as mediating the main inhibitory signals. Both types of signals were suppressed by serotonin. The efficacy of AMPA-receptor-mediated transmission displayed several types of short-term plasticity, including paired-pulse potentiation and paired-pulse depression, depending on the stimulus rate and pattern. The observed plasticity was attributed to mainly presynaptic mechanisms. To clarify some of the presynaptic factors controlling synaptic efficacy, the role of presynaptic L-type Ca2+ channels, usually assumed not to directly control transmitter release, was investigated. The analysis showed that (i) L-type channels are present in GABA-containing presynaptic terminals on MPN neurons, (ii) that these channels provide a means for differential control of spontaneous and impulse-evoked GABA release and (iii) that this differential control is prominent during short-term synaptic plasticity. A model where Ca2+ influx through L-type channels may lead to reduced GABA release via effects on Ca2+-activated K+ channels, membrane potential and other Ca2+-channel types explains the observed findings. In addition, massive Ca2+ influx through L-type channels during high-frequency stimulation may contribute to increased GABA release during post-tetanic potentiation. In conclusion, the findings obtained in the present study indicate that complex neurotransmission mechanisms and different forms of synaptic plasticity contribute to the specific functional properties of the MPN.

  • 163.
    Malinina, Evgenya
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Druzin, Michael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Johansson, Staffan
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Differential control of spontaneous and evoked GABA release by presynaptic L-type Ca2+ channels in the rat medial preoptic nucleusManuscript (preprint) (Other academic)
    Abstract [en]

    To clarify the role of presynaptic L-type Ca2+ channels in GABA-mediated transmission in the medial preoptic nucleus (MPN), spontaneous as well as impulse-evoked inhibitory postsynaptic currents (sIPSCs and eIPSCs, respectively) were recorded from MPN neurons in a slice preparation from rat brain. The effects of different stimulus protocols and pharmacological tools to detect contributions of L-type Ca2+ channels and of Ca2+-activated K+ (KCa) channels were analysed. Block of L-type channels did not affect the sIPSCs properties (frequency, amplitude, decay time course) in the absence of external stimulation, but unexpectedly potentiated the eIPSCs evoked at low stimulus frequency (0.1 – 2.0 Hz). This effect was similar to and overlapping with the effect of KCa-channel blockers. High-frequency stimulation (50 Hz for 10 s) induced a substantial post-tetanic potentiation (PTP) of the eIPSC amplitude as well as of the sIPSC frequency. Block of L-type channels still potentiated the eIPSC during PTP, but in contrast reduced the sIPSC frequency during PTP. It was concluded that L-type channels provide a means for differential control of spontaneous and impulse-evoked GABA release and that this differential control is prominent during short-term synaptic plasticity. Functional coupling of the presynaptic L-type channels to KCa channels explains the observed effects on eIPSCs.

  • 164.
    Marklund, Petter
    et al.
    Umeå University, Faculty of Social Sciences, Department of Psychology. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Fransson, P.
    Cognitive Neurophysiology Research Group, Department of Clinical Neuroscience, Karolinska Institute, Sweden.
    Cabeza, R.
    Center for Cognitive Neuroscience, Duke University, USA.
    Larsson, Anne
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Ingvar, M.
    Cognitive Neurophysiology Research Group, Department of Clinical Neuroscience, Karolinska Institute, Sweden.
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Unity and diversity of tonic and phasic executive control in episodic and working memory2007In: NeuroImage, ISSN 1053-8119, E-ISSN 1095-9572, Vol. 36, no 4, p. 1361-1373Article in journal (Refereed)
    Abstract [en]

    The present study aimed to delineate the extent to which unitary executive functions might be shared across the separate domains of episodic and working memory. A mixed blocked/event-related functional magnetic resonance imaging (fMRI) design was employed to assess sustained (tonic control) and transient (phasic control) brain responses arising from incrementing executive demand (source versus item episodic memory - vis-à-vis - two-back versus one-back working memory) using load-dependent activation overlaps as indices of common components. Although an extensive portion of the regional load effects constituted differential control modulations in both sustained and transient responses, commonalities were also found implicating a subset of executive core mechanisms consistent with unitary or domain general control. 'Unitary' control modulations were temporally dissociated into (1) shared tonic components involving medial and lateral prefrontal cortex, striatum, cerebellum and superior parietal cortex, assumed to govern enhanced top-down context processing, monitoring and sustained attention throughout task periods and (2) stimulus-synchronous phasic components encompassing posterior intraparietal sulcus, hypothesized to support dynamic shifting of the 'focus of attention' among internal representations. Taken together, these results converge with theoretical models advocating both unity and diversity among executive control processes.

  • 165. Martinsen, S.
    et al.
    Flodin, Pär
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Social Sciences, Centre for Demographic and Ageing Research (CEDAR).
    Berrebi, J.
    Lofgren, M.
    Bileviciute-Ljungar, I.
    Mannerkorpi, K.
    Ingvar, M.
    Fransson, P.
    Kosek, E.
    The role of long-term physical exercise on performance and brain activation during the Stroop colour word task in fibromyalgia patients2018In: Clinical Physiology and Functional Imaging, ISSN 1475-0961, E-ISSN 1475-097X, Vol. 38, no 3, p. 508-516Article in journal (Refereed)
    Abstract [en]

    The Stroop colour word test (SCWT) has been widely used to assess changes in cognitive performance such as processing speed, selective attention and the degree of automaticity. Moreover, the SCWT has proven to be a valuable tool to assess neuronal plasticity that is coupled to improvement in performance in clinical populations. In a previous study, we showed impaired cognitive processing during SCWT along with reduced task-related activations in patients with fibromyalgia. In this study, we used SCWT and functional magnetic resonance imagingFMRI to investigate the effects of a 15-week physical exercise intervention on cognitive performance, task-related cortical activation and distraction-induced analgesia (DIA) in patients with fibromyalgia and healthy controls. The exercise intervention yielded reduced fibromyalgia symptoms, improved cognitive processing and increased task-related activation of amygdala, but no effect on DIA. Our results suggest beneficial effects of physical exercise on cognitive functioning in FM.

  • 166. Masci, Lorenzo
    et al.
    Spang, Christoph
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    van Schie, Hans T M
    Alfredson, Håkan
    Achilles tendinopathy - do plantaris tendon removal and Achilles tendon scraping improve tendon structure?: A prospective study using ultrasound tissue characterisation2015In: BMJ Open Sport & Exercise Medicine, ISSN 2055-7647, Vol. 1, no 1, article id e000005Article in journal (Refereed)
    Abstract [en]

    Objectives The plantaris tendon has recently been described as a possible important factor in midportion Achilles tendinopathy. Ultrasound tissue characterisation (UTC) is a method to study tendon structure (matrix integrity). The effect of plantaris tendon removal on Achilles tendon structure was studied using UTC.

    Design and setting Prospective case series study at one centre.

    Participants Nine tendons in eight physically active and healthy patients (mean age 39 years) with chronic painful midportion Achilles tendinopathy were included. Preoperative two-dimensional ultrasound and UTC showed midportion Achilles tendinopathy (tendinosis) with medial tendon changes and suspected plantaris tendon involvement. Patients with previous operations to the Achilles tendon were excluded.

    Interventions Operative treatment consisted of excision of the plantaris tendon and scraping of the ventromedial surface of the Achilles tendon under a local anaesthetic.

    Primary and secondary outcome measures UTC examination and clinical scoring with the VISA-A questionnaire were performed preoperatively and 6 months postoperatively.

    Results At 6 months follow-up, UTC demonstrated a statistically significant (t=5.40, p<0.001) increase in the mean organised matrix (echo-type I+II) and a decrease in the mean disorganised matrix (echo-type III+IV). Seven out of eight patients were satisfied, and the VISA-A score had increased significantly (p<0.001) from 56.8 (range 34–73) preoperatively to 93.3 (range 87–100) postoperatively.

    Conclusions Excision of the plantaris tendon and scraping of the ventromedial Achilles tendon in chronic midportion tendinopathy seem to have the potential to improve tendon structure and reduce tendon pain. Studies on a larger group of patients and with a longer follow-up period are needed.

  • 167.
    Mata, Rui
    et al.
    University of Basel.
    von Helversen, Bettina
    University of Basel.
    Karlsson, Linnea
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Cuepper, Lutz
    RWTH Aachen University.
    Adult age differences in categorization and multiple-cue judgment2012In: Developmental Psychology, ISSN 0012-1649, E-ISSN 1939-0599, Vol. 48, no 4, p. 1188-1201Article in journal (Refereed)
    Abstract [en]

    We often need to infer unknown properties of objects from observable ones, just like detectives must infer guilt from observable clues and behavior. But how do inferential processes change with age? We examined young and older adults' reliance on rule-based and similarity-based processes in an inference task that can be considered either a categorization or a multiple-cue judgment task, depending on the nature of the criterion (binary vs. continuous). Both older and young adults relied on rule-based processes in the multiple-cue judgment task. In the categorization task, however, the majority of older adults relied on rule-based processes while young adults preferred similarity-based processes. Moreover, older adults who relied on rule-based processes performed poorly compared with young adults who relied on the same process, suggesting that aging is associated with deficits in applying rule-based processes.

  • 168.
    McLoon, Linda K.
    et al.
    University of Minnesota.
    Park, Han Na
    University of Minnesota.
    Kim, Jong-Hee
    University of Minnesota.
    Pedrosa-Domellof, Fatima
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Thompson, LaDora V.
    University of Minnesota.
    A continuum of myofibers in adult rabbit extraocular muscle: force, shortening velocity, and patterns of myosin heavy chain colocalization2011In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 111, no 4, p. 1178-1189Article in journal (Refereed)
    Abstract [en]

    Extraocular muscle (EOM) myofibers do not fit the traditional fiber typing classifications normally used in noncranial skeletal muscle, in part, due to the complexity of their individual myofibers. With single skinned myofibers isolated from rectus muscles of normal adult rabbits, force and shortening velocity were determined for 220 fibers. Each fiber was examined for myosin heavy chain (MyHC) isoform composition by densitometric analysis of electrophoresis gels. Rectus muscle serial sections were examined for coexpression of eight MyHC isoforms. A continuum was seen in single myofiber shortening velocities as well as force generation, both in absolute force (g) and specific tension (kN/m(2)). Shortening velocity correlated with MyHCIIB, IIA, and I content, the more abundant MyHC isoforms expressed within individual myofibers. Importantly, single fibers with similar or identical shortening velocities expressed significantly different ratios of MyHC isoforms. The vast majority of myofibers in both the orbital and global layers expressed more than one MyHC isoform, with up to six isoforms in single fiber segments. MyHC expression varied significantly and unpredictably along the length of single myofibers. Thus EOM myofibers represent a continuum in their histological and physiological characteristics. This continuum would facilitate fine motor control of eye position, speed, and direction of movement in all positions of gaze and with all types of eye movements-from slow vergence movements to fast saccades. To fully understand how the brain controls eye position and movements, it is critical that this significant EOM myofiber heterogeneity be integrated into hypotheses of oculomotor control.

  • 169. Miller, Norman E.
    et al.
    Michel, C. Charles
    Nanjee, M. Nazeem
    Olszewski, Waldemar L.
    Miller, Irina P.
    Hazell, Matthew
    Olivecrona, Gunilla
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Physiological chemistry.
    Sutton, Pauline
    Humphreys, Sandy M.
    Frayn, Keith N.
    Secretion of adipokines by human adipose tissue in vivo: partitioning between capillary and lymphatic transport2011In: American Journal of Physiology. Endocrinology and Metabolism, ISSN 0193-1849, E-ISSN 1522-1555, Vol. 301, no 4, p. E659-E667Article in journal (Refereed)
    Abstract [en]

    Peptides secreted by adipose tissue (adipokines) may enter blood via capillaries or lymph. The relative importance of these pathways for a given adipokine might influence its biological effects. Because this has not been studied in any species, we measured the concentrations of seven adipokines and eight nonsecreted proteins in afferent peripheral lymph and venous plasma from 12 healthy men. Data for nonsecreted proteins were used to derive indices of microvascular permeability, which in conjunction with the molecular radii of the adipokines were used to estimate the amounts leaving the tissue via capillaries. Transport rates via lymph were estimated from the lymph adipokine concentrations and lymph flow rates and total transport (secretion) as the sum of this and capillary transport. Concentrations of nonsecreted proteins were always lower in lymph than in plasma. With the exception of adiponectin, adipokine concentrations were always higher in lymph (P < 0.01). Leptin and MCP-1 were secreted at the highest rates (means: 43 mu g/h or 2.7 nmol/h and 32 mu g/h or 2.4 nmol/h, respectively). IL-6 and MCP-1 secretion rates varied greatly between subjects. The proportion of an adipokine transported via lymph was directly related to its molecular radius (r(s) = +0.94, P = 0.025, n = 6), increasing from 14 to 100% as the radius increased from 1.18 (IL-8) to 3.24 nm (TNF alpha). We conclude that the lymph/capillary partitioning of adipokines is a function of molecular size, which may affect both their regional and systemic effects in vivo. This finding may have implications for the physiology of peptides secreted by other tissues.

  • 170.
    Nelson, Lennart
    Umeå University.
    Mitochondrial differentiation during the early development of the amphibian embryo1981Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Mitochondria from Xenopus laevis and Ambystoma mexica- num embryos between fertilization and the beginning of feeding were studied: the former with respect to metabolic behaviour, enzyme pattern and carrier activity, and the latter with respect to morphological parameters.

    The metabolic behaviour of mitochondria was studied by assessing the rates of oxygen uptake in presence of various substrates. The rates of oxidation of most substrates change during development. The only substrate to be readily metabolized is glutamate (in presence of malate), whose rate of oxidation presents a peak during gastrulation and declines during larval development. The high rate of oxidation of glutamate and a high aspartate aminotransferase activity indicate that the glutamate- aspartate cycle may be predominant in early embryonic mitochondria.

    The activity of enzymes from the matrix, the inner membrane and the outer membrane were studied. During early development activities of enzymes in the various compartments change independently of each other. Furthermore, enzymes within one compartment may vary independently. Measurements of carrier activity reveal that the carrier for dicarboxylic acids displays a high activity before gastrulation and decreases thereafter, while the tricarboxylic acid, pyruvate and glutamate/OH carriers show the opposite pattern of change, their activities being low or undetectable during early development.

    This implies that a mitochondrial differentiation takes place ' during development, beginning at gastrulation when the first differentiated cells appear. In order to correlate mitochondrial and cellular differentiation, morphological parameters of mitochondria from undifferentiated and differentiated cells - Ruffini cells and epidermal cells - were analyzed. Mitochondria from the differentiated cells are significantly different from those in undifferentiated cells. Thus the processes of cell differentiation are accompanied by morphological and biochemical differentiation of the mitochondria.

  • 171.
    Neuger, Lucyna
    Umeå University, Faculty of Medicine, Medical Biosciences, Physiological chemistry. Umeå University, Faculty of Medicine, Surgical and Perioperative Sciences, Clinical Physiology.
    Aspects on lipoprotein lipase and atherosclerosis2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Lipoprotein lipase (LPL) hydrolyses blood lipids at the vascular endothelium. This action makes fatty acids available for tissue metabolic requirements. LPL is anchored to the endothelium by electrostatic forces and may act as a bridge connecting lipoproteins to cell surfaces. Clusters of positively charged amino acid residues in LPL interact with anionic groups on oligosaccharides covering the cell surfaces. Heparin competes with cell surface oligosaccharides for binding to LPL. Interaction of LPL with soluble and cell surface- ound oligosaccharides influences the activity and catabolism of the enzyme. LPL has a dual role in the development of atherosclerosis. Hydrolysis of lipoproteins by LPL contributes to clearance of lipids from plasma, resulting in an anti-atherogenic lipid profile. On the other hand, trough its bridging function, LPL contributes to lipoprotein retention at the endothelium and in the connective tissue of the artery wall. Furthermore LPL may stimulate uptake of lipoproteins in cells, converting them to foam cells. In this way LPL is considered to be proatherogenic.

    We have investigated the effects caused by a synthetic heparin analogue, RG-13577, developed for treatment of tumors by anti-angiogenesis theraphy (Paper I) and by heparin (Paper II) on the turnover and biological role of LPL. The variation of LPL activity in kidney among animal species was studied in Paper III. Localization of LPL in healthy and atherosclerotic human arteries in relation to two other heparin-binding proteins (extracellular superoxide dismutase and apolipoprotein B) was studied in Paper IV.

  • 172.
    Nevalainen, Nina
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Riklund, Katrine
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Andersson, Micael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Axelsson, Jan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Ögren, Mattias
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Lövdén, M
    Aging Research Center, Karolinska Institutet & Stockholm University, Stockholm.
    Lindenberger, U
    Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany.
    Bäckman, L
    Aging Research Center, Karolinska Institutet & Stockholm University, Stockholm.
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    COBRA: A prospective multimodal imaging study of dopamine, brain structure and function, and cognition.2015In: Brain Research, ISSN 0006-8993, E-ISSN 1872-6240, Vol. 1612, p. 83-103Article in journal (Refereed)
    Abstract [en]

    Cognitive decline is a characteristic feature of normal human aging. Previous work has demonstrated marked interindividual variability in onset and rate of decline. Such variability has been linked to factors such as maintenance of functional and structural brain integrity, genetics, and lifestyle. Still, few, if any, studies have combined a longitudinal design with repeated multimodal imaging and a comprehensive assessment of cognition as well as genetic and lifestyle factors. The present paper introduces the Cognition, Brain, and Aging (COBRA) study, in which cognitive performance and brain structure and function are measured in a cohort of 181 older adults aged 64 to 68 years at baseline. Participants will be followed longitudinally over a 10-year period, resulting in a total of three equally spaced measurement occasions. The measurement protocol at each occasion comprises a comprehensive set of behavioral and imaging measures. Cognitive performance is evaluated via computerized testing of working memory, episodic memory, perceptual speed, motor speed, implicit sequence learning, and vocabulary. Brain imaging is performed using positron emission tomography with [(11)C]-raclopride to assess dopamine D2/D3 receptor availability. Structural magnetic resonance imaging (MRI) is used for assessment of white and gray-matter integrity and cerebrovascular perfusion, and functional MRI maps brain activation during rest and active task conditions. Lifestyle descriptives are collected, and blood samples are obtained and stored for future evaluation. Here, we present selected results from the baseline assessment along with a discussion of sample characteristics and methodological considerations that determined the design of the study.

  • 173. Nielsen, Rasmus Oestergaard
    et al.
    Schjerling, Peter
    Tesch, Per
    Stål, Per
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Langberg, Henning
    Collagen content in the vastus lateralis and the soleus muscle following a 90-day bed rest period with or without resistance exercises2015In: MLTJ - Muscles Ligaments and Tendons Journal, ISSN 2240-4554, Vol. 5, no 4, p. 305-309Article in journal (Refereed)
    Abstract [en]

    Introduction: spaceflight seems associated with deterioration of the function of the skeletal muscles. Since muscle collagen is critical for muscle function, an improved understanding of the content of the muscle collagen during long-term inactivity seems important. Bed-rest with in-bed resistance training serves as a proxy for the conditions in space. Therefore, ground-based studies may improve the understanding of the consequences of long-term inactivity.

    Purpose: the purpose is to compare the change in collagen protein in the vastus lateralis (VL) and the soleus (SOL) muscle amongst persons exposed to a 90-day bed rest with or without resistance exercise.

    Methods: an explorative analysis was completed based on data from a randomized, controlled trial.The intervention group (BRE, SOL n=4, VL n=8) performed supine-based squat exercises, whereas the controls (BE, SOL n=6, VL n=12) remained inactive during follow-up. Muscle biopsies from vastus lateralis and soleus were taken at baseline(pre) and after 90-days’ follow-up (post). Muscle collagen (μg collagen/mg protein) was quantified. Two-way repeated measurements ANOVA was used to compare the interaction between the intervention (BRE/BR) and time (pre/post) for each muscle.

    Results: the collagen content of VL was similar between pre and post in the BRE group (-3.8 μg collagen/mg protein [95% CI: -22.0; 14.4], p=0.68) while it rose amongst individuals in the BR group (14.9 μg collagen/mg protein [95% CI: -0.01; 29.7], p=0.05). The difference of 18.66 [95% CI: -6.5; 43.9] between BRE and BR across time was, however, not significant (p=0.14). No significant reduction in SOL muscle collagen content was observed from pre to post in the BR group (-9.3 μg collagen/mg protein [95% CI: -24.9; 6.4], p=0.25) or in the BRE group (-6.5 μg collagen/mg protein [95% CI: -25.6; 12.6], p=0.50). There was no difference in the effect of BR versus BRE over time (mean difference -2.78 μg collagen/mg protein[95% CI: -29.7; 24.1], p=0.82).

    Conclusion: muscle collagen content in the VL or SOL muscle does not seem to differ after a 90-day bed rest period with or without squat exercises.

  • 174.
    Nilsson, Jessica
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Physiological chemistry. Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Ericsson, Madelene
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Physiological chemistry.
    Joibari, Masoumeh Motamedi
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Physiological chemistry.
    Anderson, Fredrick
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Physiological chemistry.
    Carlsson, Leif
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Nilsson, Stefan K
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Physiological chemistry.
    Sjödin, Anna
    Umeå University, Faculty of Social Sciences, Department of Food and Nutrition.
    Burén, Jonas
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine. Umeå University, Faculty of Social Sciences, Department of Food and Nutrition.
    A low-carbohydrate high-fat diet decreases lean mass and impairs cardiac function in pair-fed female C57BL/6J mice2016In: Nutrition & Metabolism, ISSN 1743-7075, E-ISSN 1743-7075, Vol. 13, article id 79Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Excess body fat is a major health issue and a risk factor for the development of numerous chronic diseases. Low-carbohydrate diets like the Atkins Diet are popular for rapid weight loss, but the long-term consequences remain the subject of debate. The Scandinavian low-carbohydrate high-fat (LCHF) diet, which has been popular in Scandinavian countries for about a decade, has very low carbohydrate content (~5 E %) but is rich in fat and includes a high proportion of saturated fatty acids. Here we investigated the metabolic and physiological consequences of a diet with a macronutrient composition similar to the Scandinavian LCHF diet and its effects on the organs, tissues, and metabolism of weight stable mice.

    METHODS: Female C57BL/6J mice were iso-energetically pair-fed for 4 weeks with standard chow or a LCHF diet. We measured body composition using echo MRI and the aerobic capacity before and after 2 and 4 weeks on diet. Cardiac function was assessed by echocardiography before and after 4 weeks on diet. The metabolic rate was measured by indirect calorimetry the fourth week of the diet. Mice were sacrificed after 4 weeks and the organ weight, triglyceride levels, and blood chemistry were analyzed, and the expression of key ketogenic, metabolic, hormonal, and inflammation genes were measured in the heart, liver, and adipose tissue depots of the mice using real-time PCR.

    RESULTS: The increase in body weight of mice fed a LCHF diet was similar to that in controls. However, while control mice maintained their body composition throughout the study, LCHF mice gained fat mass at the expense of lean mass after 2 weeks. The LCHF diet increased cardiac triglyceride content, impaired cardiac function, and reduced aerobic capacity. It also induced pronounced alterations in gene expression and substrate metabolism, indicating a unique metabolic state.

    CONCLUSIONS: Pair-fed mice eating LCHF increased their percentage of body fat at the expense of lean mass already after 2 weeks, and after 4 weeks the function of the heart deteriorated. These findings highlight the urgent need to investigate the effects of a LCHF diet on health parameters in humans.

  • 175.
    Nilsson, Lars-Göran
    et al.
    Umeå University, Faculty of Social Sciences, Centre for Population Studies (CPS).
    Sternäng, Ola
    Department of Psychology, Stockholm University, Sweden.
    Rönnlund, Michael
    Umeå University, Faculty of Social Sciences, Department of Psychology. Umeå University, Faculty of Social Sciences, Centre for Population Studies (CPS).
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Social Sciences, Centre for Population Studies (CPS).
    Challenging the notion of an early-onset of cognitive decline.2009In: Neurobiology of Aging, ISSN 0197-4580, E-ISSN 1558-1497, Vol. 30, no 4, p. 521-524; discussion 530Article in journal (Other academic)
    Abstract [en]

    Salthouse claims that cognitive aging starts around 20 years of age. The basis for this claim is cross-sectional data. He dismisses longitudinal data, which typically show the cognitive decline to start much later, around 60 years of age. He states that longitudinal data cannot be trusted because they are flawed. There is a confounding between the effects of maturation and retest effects. We challenge Salthouse's strong claim on four accounts.

  • 176.
    Nordmark, Per F.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Structural and functional changes in the brain after surgically repaired median nerve injury2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Despite the best available surgical repair, traumatic median nerve injury within the forearm typically causes lifelong impairment in hand function. This stems from an inadequate reinnervation of the nerves supporting sensory functions of the thumb, index and long finger, and of nerves supplying intrinsic hand muscles. This thesis examines whether median nerve injuries can cause structural and functional changes in the brain. Understanding such changes can help the development of new treatments for improved recovery of hand function.

    The first study introduces a novel apparatus and paradigm for examining tactile neural processing with fMRI under well-controlled behavioral conditions. The scientific issue challenged was whether, in healthy adults, different cortical areas could be involved in processing tactile stimuli depending on their temporal frequency content. In a threshold-tracking paradigm, the participants’ task was to detect oscillatory mechanical stimulations of various frequencies delivered to the tip of either left or right middle finger. Regardless of stimulated hand, tactile detection of audible frequencies (20 and 100 Hz) engaged the left auditory cortex while detection of slow object displacements (3 Hz) engaged visual cortex. These results corroborate and advance the metamodal theory of brain function, which posits that brain areas can contribute to sensory processing by performing specific computations – those for which they are specialized – regardless of input modality.

    The second and third studies concern structural and functional changes in the brain of adults with one reinnervated hand after an injury transecting the median nerve in the forearm. Healthy individuals matched for sex, handedness and age served as controls. Irrespective of side of injury (left or right), voxel-based morphometry applied on T1 MR-images revealed reductions of gray matter in the left ventral and right dorsal premotor cortex, and reductions of white matter in related commissural pathways. We interpreted these as activity-dependent structural adaptations to reduced neural processing linked to restrictions in the diversity of the natural manual dexterity repertoire caused by a disturbed innervation of the hand. Conversely, increases in gray matter were observed bilaterally in a motion-processing visual cortical area. We interpreted this as a structural manifestation of increased neural processing linked to greater dependence on vision for controlling manual dexterity due to impaired tactile innervation of the affected hand.

    To reveal functional changes in tactile cortical processing after median nerve reinnervation, we recorded brain activity using fMRI when study participants performed perceptually demanding tactile threshold-tracking and oddball detection tasks with our novel apparatus. The hand representation of the contralesional primary somatosensory cortex (S1) showed greater activity compared to the controls when the reinnervated index finger was engaged in the tasks, but strikingly also when fingers of both hands innervated by uninjured nerves were engaged, i.e., little finger of the reinnervated hand and index and little finger of the other hand. The generally increased activity indicates a general disinhibition of contralateral S1, suggesting that increased functional reorganization is an ongoing process of chronic nerve injury. In addition, prefrontal areas implicated in processes that support decision-making and response selection showed increased activity, suggesting that such processes were more computationally demanding after nerve injury.

    Together, these results indicate that brain areas can undergo significant changes after peripheral nerve injury, even when followed by best available surgical repair and reinnervation conditions. These changes can include activity-dependent structural adaptations consisting of either regional decreases or increases in gray matter concentration, which likely depend on an area's functional specialization and on changes in its processing load due to behavioral constraints imposed by the injury. Moreover, the results also suggest that the affected hand's primary cortical projection area is still in a state of ongoing functional reorganization despite the fact that peripheral reinnervation of the hand should have been completed long ago, which should inspire the development of new therapeutic regimens for what today is considered a chronic impairment.

  • 177.
    Nordmark, Per F.
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Kir och Periop, Handkirurgi.
    Johansson, Roland S.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Disinhibition of human primary somatosensory cortex after median nerve transection and reinnervationManuscript (preprint) (Other academic)
  • 178.
    Nyberg, Andre
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Section of Physiotherapy.
    Tistad, Malin
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Section of Physiotherapy. School of Education Health and Social studies, Dalarna University, Falun, Sweden.
    Wadell, Karin
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Section of Physiotherapy.
    Can the COPD web be used to promote self-management in patients with COPD in swedish primary care: a controlled pragmatic pilot trial with 3 month- and 12 month follow-up2019In: Scandinavian Journal of Primary Health Care, ISSN 0281-3432, E-ISSN 1502-7724, Vol. 37, no 1, p. 69-82Article in journal (Refereed)
    Abstract [en]

    Objective: Evaluate the feasibility of the COPD Web and its study design and study procedures and to increase the understanding of the potential effect of the tool in order to provide guidance for a future large scale trial.

    Design: Parallel-group controlled pragmatic pilot trial.

    Subjects: There was a total of 83 patients with COPD (mean age 70 +/- 8 years with a forced expiratory volume in first second percent predicted of 60 +/- 17%). The intervention group (n = 43) was introduced to and had access to the COPD Web in addition to usual care, while the control group (n = 40) received usual care alone.

    Main outcome measures: The feasibility of the COPD Web (i.e., if and how the COPD Web was used) was automatically collected through the website, while outcomes on health, conceptual knowledge, and physical activity (PA) were collected through questionnaires at baseline, 3 months and 12 months.

    Results: At 3 months, 77% of the intervention group was considered users, and the majority of time spent on the site was related to PA and exercises and was spent during the first month (>80%). In addition, the intervention group reported increased PA (odds ratio [OR] = 4.4, P < .001), increased conceptual knowledge in five domains (OR = 2.6-4.2, all P < .05), and altered disease management strategies (e.g., increased PA) (OR >= 2.7 P < .05) in comparison to the control group. The latter was also different between groups at 12 months (OR = 3.7, P = .044). Knowledge of PA was correlated with level of PA (rho = .425-.512, P < .05) as well as to the use of PA as a strategy to manage their disease (chi(2) = 11.2-32.9, P < .05).

    Conclusion: Giving patients with COPD access to the COPD Web in addition to their ordinary primary care might be an effective shorter term (3 month) strategy to promote self-management. However, these results needs to be confirmed in a definitive large-scale trial.

  • 179.
    Nyberg, Lars
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Salami, Alireza
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Andersson, Mikael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Eriksson, Johan
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Kalpouzos, Grégoria
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Kauppi, Karolina
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Lind, Johanna
    Center for Study of Human Cognition, Department of Psychology, University of Oslo, Norway.
    Pudas, Sara
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Persson, Jonas
    Department of Psychology and Stockholm Brain Institute, Stockholm University, 106 91 Stockholm, Sweden .
    Nilsson, Lars-Göran
    Department of Psychology and Stockholm Brain Institute, Stockholm University, 106 91 Stockholm, Sweden .
    Longitudinal evidence for diminished frontal cortex function in aging2010In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 107, no 52, p. 22682-22686Article in journal (Refereed)
    Abstract [en]

    Cross-sectional estimates of age-related changes in brain structure and function were compared with 6-y longitudinal estimates. The results indicated increased sensitivity of the longitudinal approach as well as qualitative differences. Critically, the cross-sectional analyses were suggestive of age-related frontal overrecruitment, whereas the longitudinal analyses revealed frontal underrecruitment with advancing age. The cross-sectional observation of overrecruitment reflected a select elderly sample. However, when followed over time, this sample showed reduced frontal recruitment. These findings dispute inferences of true age changes on the basis of age differences, hence challenging some contemporary models of neurocognitive aging, and demonstrate age-related decline in frontal brain volume as well as functional response.

  • 180.
    Nyman, Emma
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Vanoli, Davide
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Näslund, Ulf
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Grönlund, Christer
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Inter-sonographer reproducibility of carotid ultrasound plaque detection using Mannheim consensus in subclinical atherosclerosis2020In: Clinical Physiology and Functional Imaging, ISSN 1475-0961, E-ISSN 1475-097X, Vol. 40, no 1, p. 46-51Article in journal (Refereed)
    Abstract [en]

    Aims: To determine the inter-sonographer reproducibility of carotid ultrasound plaque detection using Mannheim consensus in a subclinical population and evaluate associations related to the reproducibility.

    Methods and results: Bilateral ultrasound screening for carotid plaques defined by Mannheim consensus was performed on 106 subclinical participants. Two different sonographers scanned the same participant, and reproducibility of plaque detection was measured by Cohens kappa. Associations with reproducibility were evaluated by comparing wall, and plaque characteristics between subjects with plaques identified in one and both scans. In general, the inter-sonographer reproducibility of plaque detection was substantial with a kappa value of 0 center dot 70 (95% CI 0 center dot 60-0 center dot 80). Plaques detected in only one scan had significantly lower plaque area and plaque thickness (6 center dot 82 mm(2) and 1 center dot 45 mm) as compared to plaques detected in both scans (11 center dot 65 mm(2) and 1 center dot 96 mm, P<0 center dot 001).

    Conclusion: Minor carotid plaques contribute to decreased reproducibility as compared to large plaques when screening for subclinical atherosclerosis using Mannheim consensus. Using an alternative plaque definition based on plaque thickness >1.5 mm and plaque area >10 mm(2) could increase the reproducibility of plaque detection in subclinical atherosclerosis.

  • 181.
    Nyrén, Rakel
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Physiological chemistry.
    Makoveichuk, Elena
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Physiological chemistry.
    Malla, Sandhya
    Umeå University, Faculty of Medicine, Wallenberg Centre for Molecular Medicine at Umeå University (WCMM). Umeå University, Faculty of Medicine, Department of Medical Biosciences, Physiological chemistry.
    Kersten, Sander
    Nilsson, Stefan K.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Physiological chemistry.
    Ericsson, Madelene
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Physiological chemistry.
    Olivecrona, Gunilla
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Physiological chemistry.
    Lipoprotein lipase in mouse kidney: effects of nutritional status and high-fat diet2019In: American Journal of Physiology - Renal Physiology, ISSN 1931-857X, E-ISSN 1522-1466, Vol. 316, no 3, p. F558-F571Article in journal (Refereed)
    Abstract [en]

    Activity of lipoprotein lipase (LPL) is high in mouse kidney, but the reason is poorly understood. The aim was to characterize localization, regulation, and function of LPL in kidney of C57BL/6J mice. We found LPL mainly in proximal tubules, localized inside the tubular epithelial cells, under all conditions studied. In fed mice, some LPL, colocalized with the endothelial markers CD31 and GPIHBP1 and could be removed by perfusion with heparin. indicating a vascular location. The role of angiopoietin-like protein 4 (ANGPTL4) for nutritional modulation of LPL activity was studied in wild-type and Angptl4(-/-) mice. In Angptl4(-/-) mice, kidney LPL activity remained high in fasted animals, indicating that ANGPTL4 is involved in suppression of LPL activity on fasting, like in adipose tissue. The amount of ANGPTL4 protein in kidney was low, and the protein appeared smaller in size, compared with ANGPTL4 in heart and adipose tissue. To study the influence of obesity, mice were challenged with high-fat diet for 22 wk, and LPL was studied after an overnight fast compared with fasted mice given food for 3 h. High-fat diet caused blunting of the normal adaptation of LPL activity to feeding/fasting in adipose tissue, but in kidneys this adaptation was lost only in male mice. LPL activity increases to high levels in mouse kidney after feeding, but as no difference in uptake of chylomicron triglycerides in kidneys is found between fasted and fed states, our data confinn that LPL appears to have a minor role for lipid uptake in this organ.

  • 182.
    Näsholm, Torgny
    et al.
    Swedish Univ Agr Sci SLU, Dept Forest Ecol & Management, SE-90183 Umea, Sweden.
    Högberg, Peter
    Swedish Univ Agr Sci SLU, Dept Forest Ecol & Management, SE-90183 Umeå, Sweden.
    Franklin, Oskar
    Int Inst Appl Syst Anal, A-2361 Laxenburg, Austria.
    Metcalfe, Daniel
    Swedish Univ Agr Sci SLU, Dept Forest Ecol & Management, SE-90183 Umeå, Sweden.
    Keel, Sonja G.
    Swedish Univ Agr Sci SLU, Dept Forest Ecol & Management, SE-90183 Umeå, Sweden.
    Campbell, Catherine
    SLU, Umeå Plant Sci Ctr, Dept Forest Genet & Plant Physiol, SE-90185 Umeå, Sweden.
    Hurry, Vaughan
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Linder, Sune
    SLU, Southern Swedish Forest Res Ctr, SE-23053 Alnarp, Sweden.
    Högberg, Mona N.
    Swedish Univ Agr Sci SLU, Dept Forest Ecol & Management, SE-90183 Umeå, Sweden.
    Are ectomycorrhizal fungi alleviating or aggravating nitrogen limitation of tree growth in boreal forests?2013In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 198, no 1, p. 214-221Article in journal (Refereed)
    Abstract [en]

    Symbioses between plant roots and mycorrhizal fungi are thought to enhance plant uptake of nutrients through a favourable exchange for photosynthates. Ectomycorrhizal fungi are considered to play this vital role for trees in nitrogen (N)-limited boreal forests. We followed symbiotic carbon (C)N exchange in a large-scale boreal pine forest experiment by tracing 13CO2 absorbed through tree photosynthesis and 15N injected into a soil layer in which ectomycorrhizal fungi dominate the microbial community. We detected little 15N in tree canopies, but high levels in soil microbes and in mycorrhizal root tips, illustrating effective soil N immobilization, especially in late summer, when tree belowground C allocation was high. Additions of N fertilizer to the soil before labelling shifted the incorporation of 15N from soil microbes and root tips to tree foliage. These results were tested in a model for CN exchange between trees and mycorrhizal fungi, suggesting that ectomycorrhizal fungi transfer small fractions of absorbed N to trees under N-limited conditions, but larger fractions if more N is available. We suggest that greater allocation of C from trees to ectomycorrhizal fungi increases N retention in soil mycelium, driving boreal forests towards more severe N limitation at low N supply.

  • 183.
    Ohki, Yukari
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Edin, Benoni B
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Johansson, Roland S
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Predictions specify reactive control of individual digits in manipulation.2002In: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 22, no 2, p. 600-10Article in journal (Refereed)
    Abstract [en]

    When humans proactively manipulate objects, the applied fingertip forces primarily depend on feedforward, predictive neural control mechanisms that depend on internal representations of the physical properties of the objects. Here we investigate whether predictions of object properties also control fingertip forces that subjects generate reactively. We analyzed fingertip forces reactively supporting grasp stability in a restraining task that engaged two fingers. Each finger contacted a plate mounted on a separate torque motor, and, at unpredictable times, both plates were loaded simultaneously with forces tangential to the plates or just one of the plates was loaded. Thus, the apparatus acted as though the plates were mechanically linked or as though they were two independent objects. In different test series, each with a predominant behavior of the apparatus and with interspersed catch trials, we showed that the reactive responses clearly reflected the predominant behavior of the apparatus. Whether subject performed the task with one hand or bimanually, appropriate reactive fingertip forces developed when predominantly both contact plates were loaded or just one of the plates was loaded. When a finger was unexpectedly loaded during a catch trial, a weak initial reactive response was triggered, but the effective force development was delayed by approximately 100 msec. We conclude that the predicted physical properties of an object not only control fingertip forces during proactive but also in reactive manipulative tasks. Specifically, the automatic reactive responses reflect predictions at the level of individual digits as to the mechanical linkage of items contacted by the fingertips in manipulation.

  • 184.
    Olsson, Carl-Johan
    et al.
    Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI). Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Motor imagery: if you can't do it, you won't think it2010In: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 20, no 5, p. 711-715Article in journal (Refereed)
    Abstract [en]

    Since long, motor imagery has been recognized as a method for studying motor representations. In the last few years, important advances regarding the use of motor imagery have been made. In particular, issues concerning the functional equivalence between imagery and action have been addressed, and how equivalence affects the use of imagery to study motor representations. In this paper, we review recent findings in order to highlight the current state of knowledge about motor imagery and its relation to motor action. Three topics are discussed: (i) the imagery perspective, (ii) task complexity, and (iii) the importance of physical experience. It is shown how theses factors are closely related and how previous studies may have underestimated to what extent these factors affect the interpretation of results. Practical implications for imagery interventions are considered. It is concluded that if you cannot perform an action physically, you cannot imagine it in a way that is necessary for a high degree of functional equivalence.

  • 185.
    Olsson, CJ
    Umeå University, Faculty of Medicine, Integrative Medical Biology.
    Imaging imagining actions2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Mental training has been studied extensively for the past century but we are still not completely sure how it affects brain and behavior. The aim of this doctoral thesis was to examine one aspect of mental training i.e. motor imagery. In Study I, active high jumpers were trained for 6 weeks using a motor imagery mental training program. We measured behavioral effects in motor parameters such as total height, false attempts, take off angle, and bar clearance. A significant improvement was found on the bar clearance component compared to a control group of high jumpers that did not participate in the mental training program. The results emphasize the importance of using appropriate outcome measures since mental training may affect distinct features of the movement rather than the entire movement. Study II used fMRI (functional Magnetic Resonance Imaging) to examine the neural correlates of imagery for active high jumpers, and also how imagery training affects brain activity. Active high jumpers were compared to a control group of high jumping novices and the results showed that high jumpers were able to activate motor regions, whereas controls used parts of the visual system to perform imagery of the high jump. Thus, we were able to show how important well established motor representations are in order to achieve a neural overlap between imagery and action. In study III we examined the effects after motor, mental and combined motor and mental training on a finger tapping task. Behaviorally, even though mental training improved performance, adding mental training to motor training did not improve the results beyond only using motor training. Imaging results showed that motor and mental training engaged different neural systems, with motor training associated with motor activity and mental training with visual activity. The combination of motor and mental training activated both motor and visual systems. Additionally combining motor and mental training resulted in transfer to an untrained motor sequence and neural data indicated that cerebellum mediated the transfer. The overall findings explain how mental training can be used to improve motor performance and motor parameters. Moreover, it also illustrates that the neural processes underlying such improvements may be distinct from motor training and that the brain may react differently during mental training depending on prior physical experience of the action.

  • 186.
    Olsson, Kurt Å.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Hypothalamic and cortical control of jaw reflexes1979Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The subject of the thesis is a study of the projections from low threshold oral and face afferents to the cerebral cortex and of descending motor control mechanisms originating in the cerebral cortex or the hypothalamus and influencing the jaw reflexes.Cats anaesthetized with chi oral ose were used for the experiments. Ipsi- and contralateral nerves from the oral cavity and the face were stimulated electrically. Cortical potentials were averaged and recorded. The location of the projections was related to the cytoarchi-tectonic areas of the cerebral cortex. It was found that the afferents projected to separate maximum points in areas 3a, 3b, 5a and 6aß. The projections to areas 3a and 3b were somatotopically organized, but the layout of the projections on the cortex was not facelike.The effect of monopolar anodal stimulation of the cerebral cortex on the monosynaptic jaw closing and the di synaptic jaw opening reflexes was investigated. A sequence of facilitation and inhibition of both reflexes was elicited by cortical stimulation. The effects were of short latency (2.5 ms) and could start with either facilitation or inhibition. The timecourse of the sequence was sinuslike with a period of 10 ms. The largest effect originated in the "sensory" areas 3a and 3b and not in the "motor" areas 4y and 6ag. It is suggested, that a tri gemino-cortico-tri geminai loop via area 3a may function in reflex modulation of jaw movements.The hypothalamic effects on the jaw reflexes were evoked by electrical stimulation in those parts of the hypothalamus, which are w known to generate defence, attack or feeding responses. A tenfold facilitation of the jaw closing reflex and a facilitation followed by almost complete inhibition of the jaw opening reflex were observed in the anaesthetized animal with intact cerebral cortex. The effects remained but were diminished in amplitude after cortical ablation. The descending path was located in the ventral midbrain tegmentum.It is suggested that the observed hypothalamo-tri geminai mechanism may exercise a tonic influence on the trigeminal motoneurones, thereby controlling the set points of the biting force and the rest position. The implications of this hypothesis on the etiology of bruxism and the myofascial pain-dysfunction are discussed.

  • 187.
    Omrani, Mohsen
    et al.
    Center for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada.
    Pruszynski, J. Andrew
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Center for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada.
    Murnaghan, Chantelle D.
    Center for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada.
    Scott, Stephen H.
    Center for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada ; Department of Biomedical and Molecular Sciences, Kingston, Ontario, Canada ; Department of Medicine Queen's University, Kingston, Ontario, Canada.
    Perturbation-evoked responses in primary motor cortex are modulated by behavioral context2014In: Journal of Neurophysiology, ISSN 0022-3077, E-ISSN 1522-1598, Vol. 112, no 11, p. 2985-3000Article in journal (Refereed)
    Abstract [en]

    Corrective responses to external perturbations are sensitive to the behavioral task being performed. It is believed that primary motor cortex (M1) forms part of a transcortical pathway that contributes to this sensitivity. Previous work has identified two distinct phases in the perturbation response of M1 neurons, an initial response starting similar to 20 ms after perturbation onset that does not depend on the intended motor action and a task- dependent response that begins similar to 40 ms after perturbation onset. However, this invariant initial response may reflect ongoing postural control or a task- independent response to the perturbation. The present study tested these two possibilities by examining if being engaged in an ongoing postural task before perturbation onset modulated the initial perturbation response in M1. Specifically, mechanical perturbations were applied to the shoulder and/ or elbow while the monkey maintained its hand at a central target or when it was watching a movie and not required to respond to the perturbation. As expected, corrective movements, muscle stretch responses, and M1 population activity in the late perturbation epoch were all significantly diminished in the movie task. Strikingly, initial perturbation responses (<40 ms postperturbation) remained the same across tasks, suggesting that the initial phase of M1 activity constitutes a task- independent response that is sensitive to the properties of the mechanical perturbation but not the goal of the ongoing motor task.

  • 188.
    Panarese, Alessandro
    et al.
    Scuola Superiore Sant’Anna, Pisa.
    Edin, Benoni B
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    A modified low-cost haptic interface as a tool for complex tactile stimulation2011In: Medical Engineering and Physics, ISSN 1350-4533, E-ISSN 1873-4030, Vol. 33, no 3, p. 386-390Article in journal (Refereed)
    Abstract [en]

    This study describes the development and evaluation of a platform for the investigation of the human tactile ability. Specifically, it enables precise and reproducible application of time-varying 3D force stimuli to the skin of an immobilized human limb. We proceeded in the following steps: (1) programming a low-cost haptic interface to apply time-varying 3D force stimuli to a fixed rigid target, (2) implementing a combined feed-forward/feedback controller to improve the platform's precision and reliability in force stimulation, (3) determining the optimal tuning of the control loop parameters and (4) evaluating the system's performances when applying time-varying 3D force stimuli to an immobilized human finger pad. The system's performances were evaluated in terms of the accuracy and repeatability when delivering standard 3D force stimuli, i.e., stimuli with specified force components in the normal and skin tangential directions. Within the range of forces tested (5N in various directions), the maximum difference between the actual force and the desired value during static phases was <30mN (accuracy) and the root-mean-square of the standard deviation (repeatability) was 15mN during static phases and <75mN during dynamic phases.

  • 189.
    Panarese, Alessandro
    et al.
    Scuola Superiore Sant’Anna, Pisa.
    Edin, Benoni B
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Human ability to discriminate direction of three-dimensional force stimuli applied to the finger pad2011In: Journal of Neurophysiology, ISSN 0022-3077, E-ISSN 1522-1598, Vol. 105, no 2, p. 541-547Article in journal (Refereed)
    Abstract [en]

    Sensory information from tactile mechanoreceptors located in the glabrous skin of the hand is crucial for skillful object exploration and manipulation. These mechanoreceptors reliably encode the direction of fingertip forces, and the brain certainly relies on this information in both sensorimotor and cognitive tasks. In this study, we examined human ability to discriminate the direction of force stimuli applied to the volar surface of the index fingertip on the basis of tactile information only. We show that humans can discriminate three-dimensional (3D) force stimuli whose directions differ by an angle as small as 7.1 ° in the plane tangential to the skin surface. Moreover, we found that the discrimination ability was mainly affected by the time-varying phases of the stimulus, because adding a static plateau phase to the stimulus improved the discrimination threshold only to a limited extent.

  • 190. Peolsson, Anneli
    et al.
    Löfstedt, Tommy
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Trygg, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Peolsson, Michael
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ultrasound imaging with speckle tracking of cervical muscle deformation and deformation rate: isometric contraction of patients after anterior cervical decompression and fusion for cervical disc disease and controls2012In: Manual Therapy, ISSN 1356-689X, E-ISSN 1532-2769, Vol. 17, no 6, p. 519-525Article in journal (Refereed)
    Abstract [en]

    There is currently a lack of information regarding neck muscle activity during specific exercises. The purpose of the present study was to investigate deformation and deformation rate in different layers of dorsal and ventral neck muscles during isometric neck muscle contraction in individuals after anterior cervical decompression and fusion and in healthy controls. This study included 10 individuals (mean age 60 years; SD 7.1) with a verified, long-standing neck disorder and 10 healthy, age- and sex-matched controls. Ultrasonography and post-process speckle tracking analysis was used to investigate the degree and the rate of neck muscles motions at the C4 segmental level during sub-maximal, isometric resistance of the head in a seated position. None of the analyses performed showed significant differences between groups (p > 0.05). In the dorsal muscles, both groups exhibited a higher deformation rate in the multifidus than in the trapezius, splenius, and semispinalis capitis (p ≤ 0.01). In the neck disorder group, the multifidus also showed a higher deformation rate compared to the semispinalis cervicis (p = 0.02). In the ventral muscles of patients with neck disorders, the longus colli had a higher deformation rate than the sternocleidomastoid (p = 0.02). Among the healthy controls, the multifidus showed a higher degree of deformation (p = 0.02) than the trapezius. In conclusion, our results showed no significant differences between the two groups in mechanical neck muscle activation. Larger studies with different exercises, preferably with a standardized measure of resistance, are needed to investigate whether patients and controls show differences in deformation and deformation rates in neck muscles.

  • 191.
    Pruszynski, J. Andrew
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Department of Physiology and Pharmacology; Department of Psychology; Robarts Research Institute; Brain and Mind Institute, Western University, London, Canada.
    Flanagan, J. Randall
    Johansson, Roland S.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Fast and accurate edge orientation processing during object manipulation2018In: eLIFE, E-ISSN 2050-084X, Vol. 7, article id e31200Article in journal (Refereed)
    Abstract [en]

    Quickly and accurately extracting information about a touched object’s orientation is a critical aspect of dexterous object manipulation. However, the speed and acuity of tactile edge orientation processing with respect to the fingertips as reported in previous perceptual studies appear inadequate in these respects. Here we directly establish the tactile system’s capacity to process edge-orientation information during dexterous manipulation. Participants extracted tactile information about edge orientation very quickly, using it within 200 ms of first touching the object. Participants were also strikingly accurate. With edges spanning the entire fingertip, edge-orientation resolution was better than 3° in our object manipulation task, which is several times better than reported in previous perceptual studies. Performance remained impressive even with edges as short as 2 mm, consistent with our ability to precisely manipulate very small objects. Taken together, our results radically redefine the spatial processing capacity of the tactile system.

  • 192.
    Pruszynski, J Andrew
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Johansson, Roland S
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Edge-orientation processing in first-order tactile neurons2014In: Nature Neuroscience, ISSN 1097-6256, E-ISSN 1546-1726, Vol. 17, no 10, p. 1404-1409Article in journal (Refereed)
    Abstract [en]

    A fundamental feature of first-order neurons in the tactile system is that their distal axon branches in the skin and forms many transduction sites, yielding complex receptive fields with many highly sensitive zones. We found that this arrangement constitutes a peripheral neural mechanism that allows individual neurons to signal geometric features of touched objects. Specifically, we observed that two types of first-order tactile neurons that densely innervate the glabrous skin of the human fingertips signaled edge orientation via both the intensity and the temporal structure of their responses. Moreover, we found that the spatial layout of a neuron's highly sensitive zones predicted its sensitivity to particular edge orientations. We submit that peripheral neurons in the touch-processing pathway, as with peripheral neurons in the visual-processing pathway, perform feature extraction computations that are typically attributed to neurons in the cerebral cortex.

  • 193.
    Pruszynski, J Andrew
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Centre for Neuroscience Studies, Queen's University, Kingston, Ontario K7L 3N6, Canada.
    Omrani, Mohsen
    Centre for Neuroscience Studies, Queen's University, Kingston, Ontario K7L 3N6, Canada.
    Scott, Stephen H
    Centre for Neuroscience Studies, Departments of Biomedical and Molecular Sciences, and Medicine, Queen's University, Kingston, Ontario K7L 3N6, Canada.
    Goal-dependent modulation of fast feedback responses in primary motor cortex2014In: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 34, no 13, p. 4608-4617Article in journal (Refereed)
    Abstract [en]

    Many human studies have demonstrated that rapid motor responses (i.e., muscle-stretch reflexes) to mechanical perturbations can be modified by a participant's intended response. Here, we used a novel experimental paradigm to investigate the neural mechanisms that underlie such goal-dependent modulation. Two monkeys positioned their hand in a central area against a constant load and responded to mechanical perturbations by quickly placing their hand into visually defined spatial targets. The perturbation was chosen to excite a particular proximal arm muscle or isolated neuron in primary motor cortex and two targets were placed so that the hand was pushed away from one target (OUT target) and toward the other (IN target). We chose these targets because they produced behavioral responses analogous to the classical verbal instructions used in human studies. A third centrally located target was used to examine responses with a constant goal. Arm muscles and neurons robustly responded to the perturbation and showed clear goal-dependent responses ∼35 and 70 ms after perturbation onset, respectively. Most M1 neurons and all muscles displayed larger perturbation-related responses for the OUT target than the IN target. However, a substantial number of M1 neurons showed more complex patterns of target-dependent modulation not seen in muscles, including greater activity for the IN target than the OUT target, and changes in target preference over time. Together, our results reveal complex goal-dependent modulation of fast feedback responses in M1 that are present early enough to account for goal-dependent stretch responses in arm muscles.

  • 194.
    Radovanovic, Dina
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Peikert, Kevin
    Lindström, Mona
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Pedrosa Domellöf, Fatima
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Sympathetic innervation of human muscle spindles2015In: Journal of Anatomy, ISSN 0021-8782, E-ISSN 1469-7580, Vol. 226, no 6, p. 542-548Article in journal (Refereed)
    Abstract [en]

    The aim of the present study was to investigate the presence of sympathetic innervation in human muscle spindles, using antibodies against neuropeptide Y (NPY), NPY receptors and tyrosine hydroxylase (TH). A total of 232 muscle spindles were immunohistochemically examined. NPY and NPY receptors were found on the intrafusal fibers, on the blood vessels supplying muscle spindles and on free nerve endings in the periaxial space. TH-immunoreactivity was present mainly in the spindle nerve and vessel. This is, to our knowledge, the first morphological study concerning the sympathetic innervation of the human muscle spindles. The results provide anatomical evidence for direct sympathetic innervation of the intrafusal fibers and show that sympathetic innervation is not restricted to the blood vessels supplying spindles. Knowledge about direct sympathetic innervation of the muscle spindle might expand our understanding of motor and proprioceptive dysfunction under stress conditions, for example, chronic muscle pain syndromes.

  • 195. Recirovic-Agic, Mediha
    et al.
    Jönsson, Sofia
    Tveitarås, Maria K.
    Skogstrand, Trude
    Karlsen, Tine, V
    Lidén, Åsa
    Leh, Sabine
    Ericsson, Madelene
    Umeå University, Faculty of Medicine, Department of Medical Biosciences.
    Nilsson, Stefan K.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences.
    Reed, Rolf K.
    Hultstrom, Michael
    Time course of decompensation after angiotensin II and high-salt diet in Balb/CJ mice suggests pulmonary hypertension-induced cardiorenal syndrome2019In: American Journal of Physiology. Regulatory Integrative and Comparative Physiology, ISSN 0363-6119, E-ISSN 1522-1490, Vol. 316, no 5, p. R563-R570Article in journal (Refereed)
    Abstract [en]

    The genetic background of a mouse strain determines its susceptibility to disease. C57BL/6J and Balb/CJ are two widely used inbred mouse strains that we found react dramatically differently to angiotensin II and high-salt diet (ANG II + Salt). Balb/CJ show increased mortality associated with anuria and edema formation while C57BL/6J develop arterial hypertension but do not decompensate and die. Clinical symptoms of heart failure in Balb/CJ mice gave the hypothesis that ANG II + Salt impairs cardiac function and induces cardiac remodeling in male Balb/CJ but not in male C57BL/6J mice. To test this hypothesis, we measured cardiac function using echocardiography before treatment and every day for 7 days during treatment with ANG II + Salt. Interestingly, pulsed wave Doppler of pulmonary artery flow indicated increased pulmonary vascular resistance and right ventricle systolic pressure in Balb/CJ mice, already 24 h after ANG II + Salt treatment was started. In addition, Balb/CJ mice showed abnormal diastolic filling indicated by reduced early and late filling and increased isovolumic relaxation time. Furthermore, Balb/CJ exhibited lower cardiac output compared with C57BL/6J even though they retained more sodium and water, as assessed using metabolic cages. Left posterior wall thickness increased during ANG II + Salt treatment but did not differ between the strains. In conclusion, ANG II + Salt treatment causes early restriction of pulmonary flow and reduced left ventricular filling and cardiac output in Balb/CJ, which results in fluid retention and peripheral edema. This makes Balb/CJ a potential model to study the adaptive capacity of the heart for identifying new disease mechanisms and drug targets.

  • 196.
    Salami, Alireza
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Eriksson, Johan
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Kompus, Kristiina
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Habib, Reza
    Southern Illinois University , Carbondale.
    Kauppi, Karolina
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Characterizing the neural correlates of modality-specific and modality-independent accessibility and availability signals in memory using partial-least squares2010In: NeuroImage, ISSN 1053-8119, E-ISSN 1095-9572, Vol. 52, no 2, p. 686-698Article in journal (Refereed)
    Abstract [en]

    Previous studies have shown that information that currently cannot be retrieved but will be retrieved on a subsequent, more supported task (i.e. is available but not accessible) has a distinct neural signature compared with non-available information. For verbal paired-associates, an availability signal has been revealed in left middle temporal cortex, an area potentially involved in the storage of such information, raising the possibility that availability signals are expressed in modality-specific storage sites. In the present study subjects encoded pictures and sounds representing concrete objects. One day later, during fMRI scanning, a verbal cued-recall task was administrated followed by a post-scan recognition task. Items remembered on both tasks were classified as accessible; items not remembered on the first but on the second task were classified as available; and items not remembered on any of the tasks were classified as not available. Multivariate partial-least-squares analyses revealed a modality-independent accessibility network with dominant contributions of left inferior parietal cortex, left inferior frontal cortex, and left hippocampus. Additionally, a modality-specific availability network was identified which included increased activity in visual regions for available pictorial information and in auditory regions for available sound information. These findings show that availability in memory, at least in part, is characterized by systematic changes in brain activity in sensory regions whereas memory access reflects differential activity in a modality-independent, conceptual network, thus indicating qualitative differences between availability and accessibility in memory.

  • 197.
    Salami, Alireza
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Eriksson, Johan
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Nilsson, Lars-Göran
    Stockholm University.
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Age-related white matter microstructural differences partly mediate age-related decline in processing speed but not cognition2012In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1822, no 3, p. 408-415Article in journal (Refereed)
    Abstract [en]

    Aging is associated with declining cognitive performance as well as structural changes in brain gray and white matter (WM). The WM deterioration contributes to a disconnection among distributed brain networks and may thus mediate age-related cognitive decline. The present diffusion tensor imaging (DTI) study investigated age-related differences in WM microstructure and their relation to cognition (episodic memory, visuospatial processing, fluency, and speed) in a large group of healthy subjects (n=287) covering 6 decades of the human life span. Age related decreases in fractional anisotropy (FA) and increases in mean diffusivity (MD) were observed across the entire WM skeleton as well as in specific WM tracts, supporting the WM degeneration hypothesis. The anterior section of the corpus callosum was more susceptible to aging compared to the posterior section, lending support to the anterior-posterior gradient of WM integrity in the corpus callosum. Finally, and of critical interest, WM integrity differences were found to mediate age-related reductions in processing speed but no significant mediation was found for episodic memory, visuospatial ability, or fluency. These findings suggest that compromised WM integrity is not a major contributing factor to declining cognitive performance in normal aging. This article is part of a Special Issue entitled: Imaging Brain Aging and Neurodegenerative disease.

  • 198.
    Salami, Alireza
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Eriksson, Johan
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology. Umeå University, Faculty of Medicine, Umeå Centre for Functional Brain Imaging (UFBI).
    Opposing effects of aging on large-scale brain systems for memory encoding and cognitive control2012In: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 32, no 31, p. 10749-10757Article in journal (Refereed)
    Abstract [en]

    Episodic memory declines with advancing age. Neuroimaging studies have associated such decline to age-related changes in general cognitive-control networks as well as to changes in process-specific encoding or retrieval networks. To assess the specific influence of aging on encoding and retrieval processes and associated brain systems, it is vital to dissociate encoding and retrieval from each other and from shared cognitive-control processes. We used multivariate partial-least-squares to analyze functional magnetic resonance imaging data from a large population-based sample (n = 292, 25-80 years). The participants performed a face-name paired-associates task and an active baseline task. The analysis revealed two significant network patterns. The first reflected a process-general encoding-retrieval network that included frontoparietal cortices and posterior hippocampus. The second pattern dissociated encoding and retrieval networks. The anterior hippocampus was differentially engaged during encoding. Brain scores, representing whole-brain integrated measures of how strongly an individual recruited a brain network, were correlated with cognitive performance and chronological age. The scores from the general cognitive-control network correlated negatively with episodic memory performance and positively with age. The encoding brain scores, which strongly reflected hippocampal functioning, correlated positively with episodic memory performance and negatively with age. Univariate analyses confirmed that bilateral hippocampus showed the most pronounced activity reduction in older age, and brain structure analyses found that the activity reduction partly related to hippocampus atrophy. Collectively, these findings suggest that age-related structural brain changes underlie age-related reductions in the efficient recruitment of a process-specific encoding network, which cascades into upregulated recruitment of a general cognitive-control network.

  • 199. Sasaki, Shigeto
    et al.
    Naito, Kimisato
    Yoshimura, Kazuya
    Isa, Tadashi
    Seki, Kazuhiko
    Pettersson, Lars-Gunnar
    Alstermark, Bror
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Ohki, Yukari
    Cortico-motoneuronal system and dexterous finger movements: reply2004In: Journal of Neurophysiology, ISSN 0022-3077, E-ISSN 1522-1598, Vol. 92, no 6, p. 3601-3603Article in journal (Refereed)
  • 200.
    Schlader, Zachary J.
    et al.
    Texas Hlth Presbyterian Hosp Dallas, Inst Exercise & Environm Med, Dallas, TX 75231 USA.
    Lucas, Rebekah A. I.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health. Texas Hlth Presbyterian Hosp Dallas, Inst Exercise & Environm Med, Dallas, TX 75231 USA.
    Pearson, James
    Texas Hlth Presbyterian Hosp Dallas, Inst Exercise & Environm Med, Dallas, TX 75231 USA.
    Crandall, Craig G.
    Texas Hlth Presbyterian Hosp Dallas, Inst Exercise & Environm Med, Dallas, TX 75231 USA.
    Hyperthermia does not alter the increase in cerebral perfusion during cognitive activation2013In: Experimental Physiology, ISSN 0958-0670, E-ISSN 1469-445X, Vol. 98, no 11, p. 1597-1607Article in journal (Refereed)
    Abstract [en]

    This study tested the hypothesis that hyperthermia attenuates the increase in cerebral perfusion during cognitive activation. Mean middle cerebral artery blood velocity (MCAV(mean)) served as an index of cerebral perfusion, while the nBack test (a test of working memory) was the cognitive task. Hyperthermia was characterized by elevations (P < 0.001) in skin (by 5.0 +/- 0.8 degrees C) and intestinal temperatures (by 1.3 +/- 0.1 degrees C) and reductions (P < 0.020) in mean arterial pressure (by 11 +/- 10 mmHg), end-tidal CO2 tension (by 3 +/- 6 mmHg) and MCAVmean (by 10 +/- 9 cm s(-1)). Hyperthermia had no influence on nBack test performance (mean difference from normothermia to hyperthermia, -1 +/- 11%; P = 0.276) or, counter to the hypothesis, the increase in MCAV(mean) during nBack testing (mean difference from normothermia to hyperthermia: 0 +/- 16 cm s(-1); P = 0.608). These findings indicate that the capacity to increase cerebral perfusion during cognitive activation is unaffected by hyperthermia.

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