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  • 201. Li, Shu-Chen
    et al.
    Chicherio, Christian
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    von Oertzen, Timo
    Nagel, Irene E
    Sander, Thomas
    Heekeren, Hauke R
    Lindenberger, Ulman
    Bäckman, Lars
    Ebbinghaus Revisited: Influences of the BDNF Val66Met Polymorphism on Backward Serial Recall Are Modulated by Human Aging.2010Inngår i: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 22, nr 10, s. 2164-2173Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Abstract The brain-derived neurotrophic factor (BDNF) plays an important role in activity-dependent synaptic plasticity, which underlies learning and memory. In a sample of 948 younger and older adults, we investigated whether a common Val66Met missense polymorphism (rs6265) in the BDNF gene affects the serial position curve-a fundamental phenomenon of associative memory identified by Hermann Ebbinghaus more than a century ago. We found a BDNF polymorphism effect for backward recall in older adults only, with Met-allele carriers (i.e., individuals with reduced BDNF signaling) recalling fewer items than Val homozygotes. This effect was specific to the primacy and middle portions of the serial position curve, where intralist interference and associative demands are especially high. The poorer performance of older Met-allele carriers reflected transposition errors, whereas no genetic effect was found for omissions. These findings indicate that effects of the BDNF polymorphism on episodic memory are most likely to be observed when the associative and executive demands are high. Furthermore, the findings are in line with the hypothesis that the magnitude of genetic effects on cognition is greater when brain resources are reduced, as is the case in old age.

  • 202. Li, Shu-Chen
    et al.
    Lindenberger, U
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Heekeren, H R
    Bäckman, Lars
    Dopaminergic modulation of cognition in human aging2009Inngår i: Imaging the aging brain / [ed] W Jagust & M DEsposito, Oxford: Oxford University Press , 2009, s. 71-92Kapittel i bok, del av antologi (Fagfellevurdert)
  • 203.
    Lilja-Lund, Otto
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Neurovetenskaper.
    Maripuu, Martin
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Psykiatri. Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för medicin.
    Kockum, Karin
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Neurovetenskaper.
    Andersson, Johanna
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Neurovetenskaper.
    Lindam, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Laurell, Katarina
    Longitudinal neuropsychological trajectories of idiopathic normal pressure hydrocephalus: a populationbased studyManuskript (preprint) (Annet vitenskapelig)
  • 204.
    Lindgren, Lenita
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för omvårdnad. Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Anestesiologi och intensivvård.
    Westling, Göran
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Brulin, Christine
    Umeå universitet, Medicinska fakulteten, Institutionen för omvårdnad.
    Lehtipalo, Stefan
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Anestesiologi och intensivvård.
    Andersson, Micael
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Pleasant human touch is represented in pregenual anterior cingulate cortex2012Inngår i: NeuroImage, ISSN 1053-8119, E-ISSN 1095-9572, Vol. 59, nr 4, s. 3427-3432Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Touch massage (TM) is a form of pleasant touch stimulation used as treatment in clinical settings and found to improve well-being and decrease anxiety, stress, and pain. Emotional responses reported during and after TM have been studied, but the underlying mechanisms are still largely unexplored. In this study, we used functional magnetic resonance (fMRI) to test the hypothesis that the combination of human touch (i.e. skin-to-skin contact) with movement is eliciting a specific response in brain areas coding for pleasant sensations. The design included four different touch conditions; human touch with or without movement and rubber glove with or without movement. Force (2.5N) and velocity (1.5cm/s) were held constant across conditions. The pleasantness of the four different touch stimulations was rated on a visual analog scale (VAS-scale) and human touch was rated as most pleasant, particularly in combination with movement. The fMRI results revealed that TM stimulation most strongly activated the pregenual anterior cingulate cortex (pgACC). These results are consistent with findings showing pgACC activation during various rewarding pleasant stimulations. This area is also known to be activated by both opioid analgesia and placebo. Together with these prior results, our finding furthers the understanding of the basis for positive TM treatment effects.

  • 205. Luciw, Matthew D.
    et al.
    Jarocka, Ewa
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Department of Kinesiology, Faculty of Physiotherapy, University School of Physical Education, Wroclaw 51-612, Poland.
    Edin, Benoni B.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Multi-channel EEG recordings during 3,936 grasp and lift trials with varying weight and friction2014Inngår i: Scientific Data, E-ISSN 2052-4463, Vol. 1, artikkel-id 140047Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    WAY-EEG-GAL is a dataset designed to allow critical tests of techniques to decode sensation, intention, and action from scalp EEG recordings in humans who perform a grasp-and-lift task. Twelve participants performed lifting series in which the object's weight (165, 330, or 660 g), surface friction (sandpaper, suede, or silk surface), or both, were changed unpredictably between trials, thus enforcing changes in fingertip force coordination. In each of a total of 3,936 trials, the participant was cued to reach for the object, grasp it with the thumb and index finger, lift it and hold it for a couple of seconds, put it back on the support surface, release it, and, lastly, to return the hand to a designated rest position. We recorded EEG (32 channels), EMG (five arm and hand muscles), the 3D position of both the hand and object, and force/torque at both contact plates. For each trial we provide 16 event times (e.g., 'object lift-off') and 18 measures that characterize the behaviour (e. g., 'peak grip force').

    Fulltekst (pdf)
    fulltext
  • 206.
    Lund, James P
    et al.
    Faculty of Dentistry, McGill University, Montréal, Québec, Canada .
    Sadeghi, Somayeh
    Faculty of Dentistry, McGill University, Montréal, Québec, Canada .
    Athanassiadis, Tuija
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Caram Salas, Nadia
    Faculty of Dentistry, McGill University, Montréal, Québec, Canada .
    Auclair, François
    Groupe de Recherche sur le Système Nerveux Central du FRSQ, Département de Physiologie, Faculté de Médecine, Université de Montréal, Montréal, Québec, Canada .
    Thiverge, Benoît
    Faculté de Médecine Dentaire, Université de Montréal, Montréal, Québec, Canada.
    Arsenault, Isabel
    Groupe de Recherche sur le Système Nerveux Central du FRSQ, Département de Physiologie, Faculté de Médecine, Université de Montréal, Montréal, Québec, Canada.
    Rompré, Pierre
    Faculté de Médecine Dentaire, Université de Montréal, Montréal, Québec, Canada.
    Westberg, Karl-Gunnar
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Kolta, Arlette
    Groupe de Recherche sur le Système Nerveux Central du FRSQ, Département de Physiologie, Faculté de Médecine, Université de Montréal, Montréal, Québec, Canada .
    Evidence that muscle spindle mechanoreceptor afferents play a role in chronic muscle painManuskript (Annet vitenskapelig)
  • 207.
    Lund, James P
    et al.
    Université de Montréal.
    Sadeghi, Somayeh
    McGill University, Montréal.
    Athanassiadis, Tuija
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    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 universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    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 muscle2010Inngår i: PLOS ONE, E-ISSN 1932-6203, Vol. 5, nr 6, s. e11131-Artikkel i tidsskrift (Fagfellevurdert)
    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.

    Fulltekst (pdf)
    fulltext
  • 208.
    Lundström, Maria
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för omvårdnad.
    Olofsson, Birgitta
    Umeå universitet, Medicinska fakulteten, Institutionen för omvårdnad.
    Stenvall, Michael
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Geriatrik.
    Elinge, Eva
    Englund, Undis
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Geriatrik.
    Edlund, Agneta
    Borssén, Bengt
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Gustafson, Yngve
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Geriatrik.
    Vårdprogram för patienter med höftfrakturer: ortoped-geriatriskt preoperativt vårdprogram för alla patienter med höftfraktur och postoperativt vårdprogram för patienter över 80 år med cervikala och basocervikala höftfrakturer som behandlas vid Norrlands universitets sjukhus i Umeå2004Rapport (Annet vitenskapelig)
  • 209.
    Lundström, Maria
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Geriatrik.
    Olofsson, Birgitta
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Geriatrik. Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Ortopedi.
    Stenvall, Michael
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Geriatrik.
    Karlsson, Stig
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Geriatrik.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Englund, Undis
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Geriatrik.
    Borssén, Bengt
    Svensson, Olle
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Ortopedi.
    Gustafson, Yngve
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Geriatrik.
    Postoperative delirium in old patients with femoral neck fracture: a randomized intervention study.2007Inngår i: Aging Clinical and Experimental Research, ISSN 1594-0667, E-ISSN 1720-8319, Vol. 19, nr 3, s. 178-186Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND AND AIMS: Delirium is a common postoperative complication in elderly patients which has a serious impact on outcome in terms of morbidity and costs. We examined whether a postoperative multi-factorial intervention program can reduce delirium and improve outcome in patients with femoral neck fractures.

    METHODS: One hundred and ninety-nine patients, aged 70 years and over (mean age+/-SD, 82+/-6, 74% women), were randomly assigned to postoperative care in a specialized geriatric ward or a conventional orthopedic ward. The intervention consisted of staff education focusing on the assessment, prevention and treatment of delirium and associated complications. The staff worked as a team, applying comprehensive geriatric assessment, management and rehabilitation. Patients were assessed using the Mini Mental State Examination and the Organic Brain Syndrome Scale, and delirium was diagnosed according to DSM-IV criteria.

    RESULTS: The number of days of postoperative delirium among intervention patients was fewer (5.0+/-7.1 days vs 10.2+/-13.3 days, p=0.009) compared with controls. A lower proportion of intervention patients were delirious postoperatively than controls (56/102, 54.9% vs 73/97, 75.3%, p=0.003). Eighteen percent in the intervention ward and 52% of controls were delirious after the seventh postoperative day (p<0.001). Intervention patients suffered from fewer complications, such as decubitus ulcers, urinary tract infections, nutritional complications, sleeping problems and falls, than controls. Total postoperative hospitalization was shorter in the intervention ward (28.0+/-17.9 days vs 38.0+/-40.6 days, p=0.028).

    CONCLUSIONS: Patients with postoperative delirium can be successfully treated, resulting in fewer days of delirium, fewer other complications, and shorter length of hospitalization.

  • 210. MacDonald, Stuart W S
    et al.
    Cervenka, Simon
    Farde, Lars
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Bäckman, Lars
    Extrastriatal dopamine D2 receptor binding modulates intraindividual variability in episodic recognition and executive functioning.2009Inngår i: Neuropsychologia, ISSN 0028-3932, E-ISSN 1873-3514, Vol. 47, nr 11, s. 2299-2304Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Intraindividual variability (IIV) reflects lawful but transient within-person changes in performance. Increased IIV in cognition shares systematic associations with numerous conditions characterized by alterations in dopamine (DA) neuromodulation (e.g., old age, ADHD, schizophrenia, and Parkinson's disease). In a group of normal middle-aged adults, we examined links between PET-derived measures of D2 receptor binding in striatum, orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), and hippocampus (HC) and IIV for tasks assessing recognition memory and executive functioning. An index of IIV, the intraindividual standard deviation (ISD), was computed across successful response latency trials for each cognitive outcome. Lower D2 binding in OC, ACC, and HC, but not striatum, was associated with increasing ISDs for the memory and executive measures. Consistent with neurocomputational models, the present findings suggest a role for extrastriatal DA neurotransmission in modulating variability in cognitive functioning.

  • 211. MacDonald, Stuart W S
    et al.
    Nyberg, Lars
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Fysiologi.
    Bäckman, Lars
    Intra-individual variability in behavior: links to brain structure, neurotransmission and neuronal activity.2006Inngår i: Trends in Neurosciences, ISSN 0166-2236, Vol. 29, nr 8, s. 474-80Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Intra-individual variability reflects a transient, within-person change in behavioral performance. It is a common component of aging-related cognitive decline and the behavioral changes associated with neurodegenerative and other brain-related disorders such as traumatic brain injury and schizophrenia. Behavioral changes within an individual can reflect alterations at a systems or a cellular level in the brain, and monitoring intra-individual variability can therefore provide a warning of underlying pathology. Despite frequent reports of intra-individual variability, there is little synthesis, and no direct examination of the neural underpinnings. Here, we integrate seminal findings from cognitive research across lifespans of individuals, and also neuropsychological and neurobiological findings, to identify key questions and some potential answers, and to set challenges for fostering future research into intra-individual variability.

  • 212.
    MacDonald, Stuart WS
    et al.
    Department of Psychology, University of Victoria, Victoria, British Columbia, Canada V8W 3P5.
    Karlsson, Sari
    Aging Research Center, Karolinska Institute, S-113 30 Stockholm, Sweden.
    Rieckmann, Anna
    Aging Research Center, Karolinska Institute, S-113 30 Stockholm, Sweden.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Bäckman, Lars
    Aging Research Center, Karolinska Institute, S-113 30 Stockholm, Sweden.
    Aging-related increases in behavioral variability: relations to losses of dopamine D-1 receptors2012Inngår i: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 32, nr 24, s. 8186-8191Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Intraindividual variability (IIV) reflects within-person changes in performance, such as trial-by-trial fluctuations on a reaction-time (RT) task. The neural underpinnings of IIV remain largely unknown. The neurotransmitter dopamine (DA) is of particular interest here, as human populations that exhibit DA alterations, such as the elderly, attention deficit hyperactivity disorder children, persons with schizophrenia, and Parkinson patients, also show increased behavioral IIV. We examined links between DA D-1 binding potential (BP) in multiple brain regions and IIV for the control and interference conditions of the Multi-Source Interference Task (MSIT), tapping the cingulo-fronto-parietal attention network. Participants were 18 young and 20 healthy old adults. PET and the radioligand [C-11]SCH23390 were used to determine D-1 BP. The intraindividual standard deviation (ISD) was computed across successful latency trials of the MSIT conditions, independent of mean RT differences due to age, trial, and condition. Increasing ISDs were associated with increasing age and diminished D-1 binding in several brain regions (anterior cingulate gyrus, dorsolateral prefrontal cortex, and parietal cortex) for the interference, but not control, condition. Analyses of partial associations indicate that the association between age and IIV in the interference condition was linked to D-1 receptor losses in task-relevant brain regions. These findings suggest that dysfunctional DA modulation may contribute to increased variability in cognitive performance among older adults.

  • 213.
    Macefield, Vaughan G
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Häger-Ross, Charlotte
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Johansson, Roland S
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Control of grip force during restraint of an object held between finger and thumb: responses of cutaneous afferents from the digits1996Inngår i: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 108, nr 1, s. 155-171Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Unexpected pulling and pushing loads exerted by an object held with a precision grip evoke automatic and graded increases in the grip force (normal to the grip surfaces) that prevent escape of the object; unloading elicits a decrease in grip force. Anesthesia of the digital nerves has shown that these grip reactions depend on sensory signals from the digits. In the present study we assessed the capacity of tactile afferents from the digits to trigger and scale the evoked grip responses. Using tungsten microelectrodes inserted percutaneously into the median nerve of awake human subjects, unitary recordings were made from ten FA I and 13 FA II rapidly adapting afferents, and 12 SA I and 18 SA II slowly adapting afferents. While the subject held a manipulandum between a finger and the thumb, tangential load forces were applied to the receptor-bearing digit (index, middle, or ring finger or thumb) as trapezoidal load-force profiles with a plateau amplitude of 0.5-2.0 N and rates of loading and unloading at 2-8 N/s, or as "step-loads" of 0.5 N delivered at 32 N/s. Such load trials were delivered in both the distal (pulling) and proximal (pushing) direction. FA I afferents responded consistently to the load forces, being recruited during the loading and unloading phases. During the loading ramp the ensemble discharge of the FA I afferents reflected the first time-derivative of the load force (i.e., the load-force rate). These afferents were relatively insensitive to the subject's grip force responses. However, high static finger forces appeared to suppress excitation of these afferents during the unloading phase. The FA II afferents were largely insensitive to the load trials: only with the step-loads did some afferents respond. Both classes of SA afferents were sensitive to load force and grip force, and discharge rates were graded by the rate of loading. The firing of the SA I afferents appeared to be relatively more influenced by the subject's grip-force response than the discharge of the SA II afferents, which were more influenced by the load-force stimulus. The direction in which the tangential load force was applied to the skin influenced the firing of most afferents and in particular the SA II afferents. Individual afferents within each class (except for the FA IIs) responded to the loading ramp before the onset of the subject's grip response and may thus be responsible for initiating the automatic increase in grip force. However, nearly half of the FA I afferents recruited by the load trials responded to the loading phase early enough to trigger the subject's grip-force response, whereas only ca. one-fifth of the SA Is and SA IIs did so. These observations, together with the high density of FA I receptors in the digits, might place the FA I afferents in a unique position to convey the information required to initiate and scale the reactive grip-force responses to the imposed load forces.

  • 214.
    Macefield, Vaughan G
    et al.
    Prince of Wales Medical Research Institute, UNSW, Barker St., Randwick, Sydney.
    Johansson, Roland S
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    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.2003Inngår i: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 152, nr 2, s. 143-149Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 215. Maitland, Scott B
    et al.
    Herlitz, Agneta
    Nyberg, Lars
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Fysiologi.
    Bäckman, Lars
    Nilsson, Lars-Göran
    Selective sex differences in declarative memory.2004Inngår i: Mem Cognit, ISSN 0090-502X, Vol. 32, nr 7, s. 1160-9Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sex invariance of a six-factor, higher order model of declarative memory (two second-order factors: episodic and semantic memory; and four first-order factors: recall, recognition, fluency, and knowledge) was established for 1,796 participants (35-85 years). Metric invariance of first- and second-order factor loadings across sex was demonstrated. At the second-order level, a female advantage was observed for both episodic and semantic memory. At the first-order level, sex differences in episodic memory were apparent for both recall and recognition, whereas the differences in semantic memory were driven by a female superiority in fluency. Additional tests of sex differences in three age groups (35-50, 55-65, and 70-85 years of age) indicated that the female superiority in declarative memory diminished with advancing age. The factor-specific sex differences are discussed in relation to sex differences in hippocampal function.

  • 216.
    Malinina, Evgenya
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Fysiologi.
    Neurotransmission and functional synaptic plasticity in the rat medial preoptic nucleus2009Doktoravhandling, med artikler (Annet vitenskapelig)
    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.

    Fulltekst (pdf)
    FULLTEXT01
  • 217.
    Malinina, Evgenya
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Druzin, Michael
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Johansson, Staffan
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Differential control of spontaneous and evoked GABA release by presynaptic L-type Ca2+ channels in the rat medial preoptic nucleusManuskript (Annet vitenskapelig)
    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.

  • 218.
    Malinina, Evgenya
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Druzin, Michael
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Johansson, Staffan
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Differential control of spontaneous and evoked GABA release by presynaptic L-type Ca(2+) channels in the rat medial preoptic nucleus2010Inngår i: Journal of Neurophysiology, ISSN 0022-3077, E-ISSN 1522-1598, Vol. 104, nr 1, s. 200-209Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To clarify the role of presynaptic L-type Ca(2+) channels in GABA-mediated transmission in the medial preoptic nucleus (MPN), spontaneous, miniature, and impulse-evoked inhibitory postsynaptic currents (sIPSCs, mIPSCs, 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 Ca(2+) channels and of Ca(2+)-activated K(+) (K(Ca)) channels were analyzed. Block of L-type channels did not affect the sIPSC and mIPSC 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 K(Ca)-channel blockers. High-frequency stimulation (50 Hz for 10 s) induced a substantial posttetanic potentiation (PTP) of the eIPSC amplitude and 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 K(Ca) channels explains the observed effects on eIPSCs.

  • 219.
    Malinina, Evgenya
    et al.
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Fysiologi.
    Druzin, Michael
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Fysiologi.
    Johansson, Staffan
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Fysiologi.
    Fast neurotransmission in the rat medial preoptic nucleus.2005Inngår i: Brain Research, ISSN 0006-8993, Vol. 1040, nr 1-2, s. 157-68Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The functional properties of neurotransmission in the medial preoptic nucleus (MPN) were studied in a brain slice preparation from young male rats. The aims were to evaluate the thin slice preparation for studying evoked synaptic responses in MPN neurons, to characterize the fast responses triggered by activation of presynaptic nerve fibers in the MPN, and to identify the involved receptor types. Presynaptic stimulation within the MPN evoked postsynaptic voltage and current responses that were blocked by 200 microM Cd2+ or by 2.0 microM tetrodotoxin and were attributed to action potential-evoked transmitter release. The relation to stimulus strength and comparison with spontaneous synaptic currents suggested that in many cases only one presynaptic nerve fiber was excited by the stimulus. Furthermore, the transmission was probabilistic in nature, with frequent failures. Thus, response probability, most likely reflecting transmitter release probability, could be evaluated in the thin slice preparation. Evoked excitatory postsynaptic currents recorded under voltage-clamp conditions were, due to kinetics, I-V relation, and pharmacological properties, attributed to AMPA/kainate receptors and NMDA receptors, whereas inhibitory currents were attributed to GABAA receptors. No responses that could be attributed to glycine or other types of primary transmitters were detected. Although serotonin (5-HT) did not appear to function as a primary transmitter, glutamate- as well as GABA-mediated transmission was suppressed by 500 microM 5-HT, with a clear reduction in response probability observed. 5-HT also reduced the frequency, but not the amplitude, of spontaneous postsynaptic currents and was therefore ascribed a presynaptic site of action.

  • 220.
    Malinina, Evgenya
    et al.
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Fysiologi.
    Druzin, Michael
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Fysiologi.
    Johansson, Staffan
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Fysiologi.
    Short-term plasticity in excitatory synapses of the rat medial preoptic nucleus.2006Inngår i: Brain Research, ISSN 0006-8993, Vol. 1110, nr 1, s. 128-35Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The medial preoptic nucleus (MPN) regulates sexual behavior which is subject to experience-dependent modifications. Such modifications must depend on functional plasticity in the controlling neural circuits. Thus, MPN synapses are likely candidates for the site of alterations. The present work is a first systematic study of functional synaptic plasticity at glutamatergic synapses in the MPN. Short-term activity-dependent plasticity was investigated using a slice preparation from young male rats. The average efficacy of AMPA/kainate-receptor-mediated synaptic transmission was activity-dependent, showing a peak at a steady stimulation rate of 2 Hz. The variation in efficacy was attributed to mainly presynaptic factors since the average response amplitude was roughly paralleled by the response probability. Upon paired-pulse stimulation, paired-pulse facilitation as well as paired-pulse depression was observed. In some cases, paired-pulse facilitation as well as paired-pulse depression was recorded from an individual neuron depending on the interval between the paired stimuli. On average, paired-pulse facilitation was observed at intervals <500 ms, and paired-pulse depression at intervals in the range 1-4 s. The findings thus reveal complex activity-dependent short-term plasticity of the functional synaptic properties in the medial preoptic nucleus.

  • 221.
    Malmberg Gavelin, Hanna
    et al.
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Stigsdotter Neely, Anna
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi. Department of Social and Psychological Studies, Karlstad University, Karlstad, Sweden.
    Andersson, Micael
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Eskilsson, Therese
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Fysioterapi.
    Slunga Järvholm, Lisbeth
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Boraxbekk, Carl-Johan
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Samhällsvetenskapliga fakulteten, Enheten för demografi och åldrandeforskning (CEDAR). Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Denmark.
    Neural activation in stress-related exhaustion: cross-sectional observations and interventional effects2017Inngår i: Psychiatry Research: Neuroimaging, ISSN 0925-4927, E-ISSN 1872-7506, Vol. 269, s. 17-25Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The primary purpose of this study was to investigate the association between burnout and neural activation during working memory processing in patients with stress-related exhaustion. Additionally, we investigated the neural effects of cognitive training as part of stress rehabilitation. Fifty-five patients with clinical diagnosis of exhaustion disorder were administered the n-back task during fMRI scanning at baseline. Ten patients completed a 12-week cognitive training intervention, as an addition to stress rehabilitation. Eleven patients served as a treatment-as-usual control group. At baseline, burnout level was positively associated with neural activation in the rostral prefrontal cortex, the posterior parietal cortex and the striatum, primarily in the 2-back condition. Following stress rehabilitation, the striatal activity decreased as a function of improved levels of burnout. No significant association between burnout level and working memory performance was found, however, our findings indicate that frontostriatal neural responses related to working memory were modulated by burnout severity. We suggest that patients with high levels of burnout need to recruit additional cognitive resources to uphold task performance. Following cognitive training, increased neural activation was observed during 3-back in working memory-related regions, including the striatum, however, low sample size limits any firm conclusions.

  • 222.
    Mansson, Kristoffer N.
    et al.
    Linköping, Sweden.
    Salami, Alireza
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Stockholm, Sweden.
    Frick, Andreas
    Uppsala, Sweden.
    Carlbring, Per
    Stockholm, Sweden.
    Furmark, Tomas
    Uppsala, Sweden.
    Olsson, Carl-Johan
    Umeå universitet, Samhällsvetenskapliga fakulteten, Centrum för befolkningsstudier (CBS). Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Andersson, Gerhard
    Linköping, Sweden; Stockholm, Sweden.
    Interrelated Functional and Structural Amygdala Plasticity Following Internet-delivered Cognitive Behavior Therapy for Social Anxiety Disorder2015Inngår i: Biological Psychiatry, ISSN 0006-3223, E-ISSN 1873-2402, Vol. 77, nr 9 Suppl., s. 51S-51SArtikkel i tidsskrift (Annet vitenskapelig)
  • 223.
    Marklund, Petter
    et al.
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    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 universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Ingvar, M.
    Cognitive Neurophysiology Research Group, Department of Clinical Neuroscience, Karolinska Institute, Sweden.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Unity and diversity of tonic and phasic executive control in episodic and working memory2007Inngår i: NeuroImage, ISSN 1053-8119, E-ISSN 1095-9572, Vol. 36, nr 4, s. 1361-1373Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 224.
    Marklund, Petter
    et al.
    Umeå universitet, Samhällsvetenskaplig fakultet, Psykologi.
    Fransson, Per
    Umeå universitet, Samhällsvetenskaplig fakultet, Psykologi.
    Cabeza, Roberto
    Petersson, Karl M
    Ingvar, Martin
    Nyberg, Lars
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Fysiologi.
    Sustained and transient neural modulations in prefrontal cortex related to declarative long-term memory, working memory, and attention.2007Inngår i: Cortex, ISSN 0010-9452, Vol. 43, nr 1, s. 22-37Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Common activations in prefrontal cortex (PFC) during episodic and semantic long-term memory (LTM) tasks have been hypothesized to reflect functional overlap in terms of working memory (WM) and cognitive control. To evaluate a WM account of LTM-general activations, the present study took into consideration that cognitive task performance depends on the dynamic operation of multiple component processes, some of which are stimulus-synchronous and transient in nature; and some that are engaged throughout a task in a sustained fashion. PFC and WM may be implicated in both of these temporally independent components. To elucidate these possibilities we employed mixed blocked/event-related functional magnetic resonance imaging (fMRI) procedures to assess the extent to which sustained or transient activation patterns overlapped across tasks indexing episodic and semantic LTM, attention (ATT), and WM. Within PFC, ventrolateral and medial areas exhibited sustained activity across all tasks, whereas more anterior regions including right frontopolar cortex were commonly engaged in sustained processing during the three memory tasks. These findings do not support a WM account of sustained frontal responses during LTM tasks, but instead suggest that the pattern that was common to all tasks reflects general attentional set/vigilance, and that the shared WM-LTM pattern mediates control processes related to upholding task set. Transient responses during the three memory tasks were assessed relative to ATT to isolate item-specific mnemonic processes and were found to be largely distinct from sustained effects. Task-specific effects were observed for each memory task. In addition, a common item response for all memory tasks involved left dorsolateral PFC (DLPFC). The latter response might be seen as reflecting WM processes during LTM retrieval. Thus, our findings suggest that a WM account of shared PFC recruitment in LTM tasks holds for common transient item-related responses rather than sustained state-related responses that are better seen as reflecting more general attentional/control processes.

  • 225. Marklund, Petter
    et al.
    Larsson, Anne
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Elgh, Eva
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Geriatrik.
    Linder, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Neurologi.
    Riklund Åhlström, Katrine
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Forsgren, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Neurologi.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Temporal dynamics of basal ganglia under-recruitment in Parkinson's disease: transient caudate abnormalities during updating of working memory.2009Inngår i: Brain, ISSN 0006-8950, E-ISSN 1460-2156, Vol. 132, nr Pt 2, s. 336-346Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Using hybrid-blocked/event-related fMRI and the 2-back task we aimed to decompose tonic and phasic temporal dynamics of basal ganglia response abnormalities in working memory associated with early untreated Parkinson's disease. In view of the tonic/phasic dopamine hypothesis, which posits a functional division between phasic D(2)-dependent striatal updating processes and tonic D(1)-dependent prefrontal context-maintenance processes, we predicted that newly diagnosed, drug-naïve Parkinson's disease patients, with selective striatal dopamine deprivation, would demonstrate transient rather than sustained activation changes in the basal ganglia during 2-back performance. Task-related activation patterns within discrete basal ganglia structures were directly compared between patients and healthy elderly controls. The obtained results yielded uniquely transient underactivation foci in caudate nuclei, putamen and globus pallidus in Parkinson's disease patients, which indicates suboptimal phasic implementation of striatal D(2)-dependent gating mechanisms during updating. Sustained underactivation was only seen in the anterior putamen, which may reflect initial signs of tonic control impairment. No significant changes were exhibited in prefrontal cortex. The present findings resonate well with the tonic/phasic dopamine account and suggest that basal ganglia under-recruitment associated with executive dysfunction in early Parkinson's disease might predominantly stem from deficiencies in phasic executive components subserved by striatum.

  • 226.
    Marklund, Petter
    et al.
    Department of Psychology, Stockholm University, Stockholm Brain Institute, Stockholm, Sweden.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Intersecting the divide between working and episodic memory: evidence from sustained and transient brain activity patterns2007Inngår i: The conitive neruoscience of working memory / [ed] Naoyuki Osaka; Robert H. Logie; Mark D'Esposito, Oxford: Oxford University Press, 2007, s. 305-332Kapittel i bok, del av antologi (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    This chapter reviews positron emission tomography (PET), functional magnetic resonance imaging (fMRI), and event-related potential (ERP) studies of episodic memory retrieval, working memory and of executive control, and concludes that working memory may comprise a range of control functions linked with the operation of the prefrontal cortex that serve to retrieve information from long-term memory in more posterior areas and to maintain the information in an active state. This views the memory components of working memory as comprising the currently activated areas of long-term memory rather than a quite distinct temporary memory system.

  • 227. Marusiak, Jaroslaw
    et al.
    Jarocka, Ewa
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Jaskolska, Anna
    Jaskolski, Artur
    Influence of number of records on reliability of myotonometric measurements of muscle stiffness at rest and contraction2018Inngår i: ACTA OF BIOENGINEERING AND BIOMECHANICS, ISSN 1509-409X, Vol. 20, nr 3, s. 123-131Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Purpose: The aim of this study was to determine an effect of myotonometric records' number on stiffness measurements' reliability in muscles at rest and contraction. Methods: Muscle stiffness was measured using Myoton-3 device. Twenty records were taken for: (i) biceps (BB) and triceps brachii (TB) at rest and for BB at 10% of maximal voluntary contraction (MVC) in healthy elderlies (HE) and in Parkinson's disease patients (PD); and (ii) brachioradialis (BR) at rest and at 25, 50 and 80% MVC in healthy young (HY) subjects. Also, in HY group, the 3-records mode was used for BR's measurements at maximal contraction. Each measurement taken with 20-records was classed into five records groups: the whole 20- and the first 15-, 10-, 5- and 3-records. Test-retest reliability for these records groups was analyzed. Results: In HE and PD group measurements' reliability was excellent for all groups of records (20-3 records). In HY group, for the five groups of records taken at rest and submaximal levels of contraction (25, 50 and 80% MVC) the measurements reliability: (i) was mostly excellent or rarely average; and (ii) only in one per three 50% MVC conditions was unacceptable, i.e., for the 3-records group. The reliability of 3-records mode measurements at maximal contraction were unacceptable. Conclusions: Reliable myotonometric stiffness measurements in muscles at rest and during submaximal contractions can be achieved with less than 20 records (15, 10, 5 records) and even for the most of measurements with 3 records in HY and HE as well as in the PD patients. Myotonometric stiffness measurements with 3-records mode during maximal contraction were not reliable.

  • 228.
    Mata, Rui
    et al.
    University of Basel.
    von Helversen, Bettina
    University of Basel.
    Karlsson, Linnea
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Cuepper, Lutz
    RWTH Aachen University.
    Adult age differences in categorization and multiple-cue judgment2012Inngår i: Developmental Psychology, ISSN 0012-1649, E-ISSN 1939-0599, Vol. 48, nr 4, s. 1188-1201Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 229.
    McGarity-Shipley, Michael R.
    et al.
    Centre for Neuroscience Studies, Queen's University, ON, Kingston, Canada.
    Jantz, Simona Markovik
    Centre for Neuroscience Studies, Queen's University, ON, Kingston, Canada.
    Johansson, Roland S.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Wolpert, Daniel M.
    Department of Neuroscience, Columbia University, New York, United States; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, United States.
    Randall Flanagan, J.
    Centre for Neuroscience Studies, Queen's University, ON, Kingston, Canada; Department of Psychology, Queen's University, ON, Kingston, Canada.
    Fast feedback responses to categorical sensorimotor errors that do not indicate error magnitude are optimized based on short and long term memory2023Inngår i: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 43, nr 49Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Skilled motor performance depends critically on rapid corrective responses that act to preserve the goal of the movement in the face of perturbations. Although it is well established that the gain of corrective responses elicited while reaching towards objects adapts to different contexts, little is known about the adaptability of corrective responses supporting the manipulation of objects after they are grasped. Here we investigated the adaptability of the corrective response elicited when an object being lifted is heavier than expected and fails to lift off when predicted. This response involves a monotonic increase in vertical load force triggered, within ∼90 ms, by the absence of expected sensory feedback signaling lift-off, and terminated when actual lift-off occurs. Critically, because the actual weight of the object cannot be directly sensed at the moment the object fails to lift-off, any adaptation of the corrective response would have to be based on memory from previous lifts. We show that when humans, including men and women, repeatedly lift an object that, on occasional catch trials, increases from a baseline weight to a fixed heavier weight, they scale the gain of the response (i.e., the rate of force increase) to the heavier weight within 2-3 catch trials. We also show that the gain of the response scales, on the first catch trial, with the baseline weight of the object. Thus, the gain of the lifting response can be adapted by both short and long term experience. Finally, we demonstrate that this adaptation preserves the efficacy of the response across contexts.

  • 230.
    McGlone, Francis
    et al.
    University of Wales, Bangor.
    Kelly, Edward F
    University of North Carolina.
    Trulsson, Mats
    Karolinska Institute.
    Francis, Susan T
    University of Nottingham.
    Westling, Göran
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Bowtell, Richard
    University of Nottingham.
    Functional neuroimaging studies of human somatosensory cortex2002Inngår i: Behavioural Brain Research, ISSN 0166-4328, E-ISSN 1872-7549, Vol. 135, nr 1-2, s. 147-158, PII S0166-4328(02)00144-4Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two studies were carried out to assess the applicability of echoplanar fMRI at 3.0 T to the analysis of somatosensory mechanisms in humans. Vibrotactile stimulation of the tips of digits two and five reliably generated significant clusters of activation in primary (SI) and secondary (SII) somatosensory cortex, area 43, the pre-central gyrus, posterior insula, posterior parietal cortex and posterior cingulate. Separation of these responses by digit in SI was possible in all subjects and the activation sites reflected the known lateral position of the representation of digit 2 relative to that of digit 5. A second study employed microneurographic techniques in which individual median-nerve mechanoreceptive afferents were isolated, physiologically characterized, and microstimulated in conjunction with fMRI. Hemodynamic responses, observed in every case, were robust, focal, and physiologically orderly. These techniques will enable more detailed studies of the representation of the body surface in human somatosensory cortex, the relationship of that organization to short-term plasticity in responses to natural tactile stimuli, and effects of stimulus patterning and unimodal/cross-modal attentional manipulations. They also present unique opportunities to investigate the basic physiology of the BOLD effect, and to optimize the operating characteristics of two important human functional neuroimaging modalities-high-field fMRI and high-resolution EEG-in an unusually specific and well-characterized neurophysiological setting.

  • 231.
    Naesström, Matilda
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Psykiatri.
    Eriksson, Johan
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Blomstedt, Patric
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Neurovetenskaper.
    Bodlund, Owe
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Psykiatri.
    Functional MRI Evaluation of Deep Brain Stimulation of Bed Nucleus of Stria Terminalis in Obsessive-Compulsive DisorderManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Deep brain stimulation (DBS) is under investigation as a treatment for resistant obsessivecompulsive disorder (OCD). OCD is theorized to be caused by dysregulation in corticostriato-thalamo-cortical networks, including structures associated with emotional and cognitive processing such as the bed nucleus of stria terminalis (BNST), pre-supplementary motor area (pre-SMA) and anterior insula. As a crucial part of the anxiety circuit the BNST has been proposed as a target for DBS in OCD. However, the mechanism of action of BNST DBS in OCD is not yet fully understood. The aim of this study was to investigate how DBS affects anxiety-related brain activity in patients with severe obsessive-compulsive disorder, and explore which areas of the brain are possibly involved in the treatment. Six patients undergoing DBS in the BNST for sever OCD were evaluated with symptom provocation fMRI pre-operatively and in DBS on and off conditions. Anxiety-related brain activity was identified by contrasting anxiety-provoking images versus neutral images, and included the anterior insula and the pre-SMA. In the pre-SMA a significant decrease was seen in 3/6 patients, with a nominally similar reduction in the other three patients. In the anterior insula, the change was significant in half of the patients, again showing a similar pattern across the whole group. We hypothesize that possible mechanisms of BNST DBS in OCD could be modulation of anxiety related activity in the pre-SMA and anterior insula, two regions that plays an important role in the pathophysiology of OCD.

  • 232.
    Nagel, Irene E
    et al.
    Max Planck Institute for Human Development, Berlin, Freie Universität Berlin.
    Preuschhof, Claudia
    Max Planck Institute for Human Development, Berlin, Freie Universität Berlin.
    Li, Shu-Chen
    Max Planck Institute for Human Development, Berlin.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Bäckman, Lars
    Max Planck Institute for Human Development, Berlin, Karolinska Institute.
    Lindenberger, Ulman
    Max Planck Institute for Human Development, Berlin.
    Heekeren, Hauke R
    x Planck Institute for Human Development, Berlin, Freie Universität Berlin.
    Load Modulation of BOLD Response and Connectivity Predicts Working Memory Performance in Younger and Older Adults.2011Inngår i: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 23, nr 8, s. 2030-2045Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Individual differences in working memory (WM) performance have rarely been related to individual differences in the functional responsivity of the WM brain network. By neglecting person-to-person variation, comparisons of network activity between younger and older adults using functional imaging techniques often confound differences in activity with age trends in WM performance. Using functional magnetic resonance imaging, we investigated the relations among WM performance, neural activity in the WM network, and adult age using a parametric letter n-back task in 30 younger adults (21-31 years) and 30 older adults (60-71 years). Individual differences in the WM network's responsivity to increasing task difficulty were related to WM performance, with a more responsive BOLD signal predicting greater WM proficiency. Furthermore, individuals with higher WM performance showed greater change in connectivity between left dorsolateral prefrontal cortex and left premotor cortex across load. We conclude that a more responsive WM network contributes to higher WM performance, regardless of adult age. Our results support the notion that individual differences in WM performance are important to consider when studying the WM network, particularly in age-comparative studies.

  • 233. Nagel, Irene E
    et al.
    Preuschhof, Claudia
    Li, Shu-Chen
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Bäckman, Lars
    Lindenberger, Ulman
    Heekeren, Hauke R
    Performance level modulates adult age differences in brain activation during spatial working memory.2009Inngår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 106, nr 52, s. 22552-22557Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Working memory (WM) shows pronounced age-related decline. Functional magnetic resonance imaging (fMRI) studies have revealed age differences in task-related brain activation. Evidence based primarily on episodic memory studies suggests that brain activation patterns can be modulated by task difficulty in both younger and older adults. In most fMRI aging studies on WM, however, performance level has not been considered, so that age differences in activation patterns are confounded with age differences in performance level. Here, we address this issue by comparing younger and older low and high performers in an event-related fMRI study. Thirty younger (20-30 years) and 30 older (60-70 years) healthy adults were tested with a spatial WM task with three load levels. A region-of-interest analysis revealed marked differences in the activation patterns between high and low performers in both age groups. Critically, among the older adults, a more "youth-like" load-dependent modulation of the blood oxygen level-dependent signal was associated with higher levels of spatial WM performance. These findings underscore the need of taking performance level into account when studying changes in functional brain activation patterns from early to late adulthood.

  • 234.
    Naghavi, Hamid Reza
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Eriksson, Johan
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Larsson, Anne
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Cortical regions underlying successful encoding of semantically congruent and incongruent associations between common auditory and visual objects.2011Inngår i: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 505, nr 2, s. 191-195Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recent studies implicate regions in the frontal, temporal and occipital cortices of the brain in audio-visual (AV) integration of familiar objects. It remains unclear, however, which brain regions contribute to the creation of object-related AV memories, and whether activation of these regions is affected by crossmodal congruency. Here we used event-related functional MRI in a subsequent memory paradigm to investigate the neural substrates of successful encoding of semantically congruent and incongruent AV memories. Creation of both types of memories activated a region in the left inferior frontal gyrus (IFG). In addition, successful encoding of semantically related and unrelated AV pairs was correlated with increased activity in regions within the right lateral occipital cortex and bilateral lateral temporal cortex, respectively. These results may highlight a common role of IFG in retrieval of semantic information during encoding and suggest that the occipital and temporal cortices differentially process perceptual versus conceptual associations of AV memories.

  • 235.
    Naghavi, Hamid Reza
    et al.
    Tehran University of Medical Sciences, Institute for Cognitive Science Studies, Tehran, Iran.
    Eriksson, Johan
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Larsson, Anne
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    The claustrum/insula region integrates conceptually related sounds and pictures2007Inngår i: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 422, nr 1, s. 77-80Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The brain is able to create coherent percepts from multisensory input. This phenomenon, known as multisensory integration (MSI), is a ubiquitous feature of everyday life and has been found to be essential for a reliable interaction with the environment. Recent functional neuroimaging studies suggest that several different networks are engaged in various forms of MSI depending on the nature of information being integrated. However, little is known about the neural basis of a fundamental form of MSI in natural conditions; integration of common auditory and visual objects which are conceptually related, such as when we look at a cat and hear a meowing sound. Here we used event-related fMRI to compare the brain response to conceptually related and unrelated pairs of audio-visual stimuli denoting common objects. Our protocol was designed to preclude contamination of the results by cognitive processes additional to those needed for MSI. The results indicate that higher-order temporal and occipital areas respond to coincident sounds and pictures regardless of their semantic relationship; whereas, the right claustrum/insula region is differentially activated in association with multisensory integration of conceptually related common objects. This observation has important implications for understanding how multimodal information about common objects is represented in the brain.

  • 236.
    Naghavi, Hamid Reza
    et al.
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi.
    Lind, Johanna
    Department of Psychology, University of Oslo, Oslo, Norway.
    Nilsson, Lars-Göran
    Department of Psychology, Stockholm University, Stockholm, Sweden.
    Adolfsson, Rolf
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Psykiatri.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Personality traits predict response to novel and familiar stimuli in the hippocampal region2009Inngår i: Psychiatry Research, ISSN 0165-1781, E-ISSN 1872-7123, Vol. 173, nr 2, s. 94-99Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Current evidence from genetic, neurochemical, and clinical research supports the notion that a combination of high novelty seeking and low harm avoidance traits (NS-ha) is reliably dissociable from the opposite personality profile (i.e., low novelty seeking and high harm avoidance, ns-HA). Little is known, however, about how the differences between these two types of personality are regulated by brain function. Here we used functional magnetic resonance imaging (fMRI) and recruited two groups of individuals, one group with the NS-ha profile and the other group with the ns-HA profile, to examine whether there is a difference between the two groups in their brain response to novel versus familiar word stimuli. Results revealed a differential pattern of response in an area in the hippocampal region, with the NS-ha group showing a greater sensitivity to novel stimuli and the ns-HA group demonstrating a greater response to familiar stimuli. We conclude that the response pattern to novel and familiar stimuli in the hippocampal region has a role in mediating differences between the NS-ha and ns-HA temperamental profiles.

  • 237. Naghavi, Hamid Reza
    et al.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Common fronto-parietal activity in attention, memory, and consciousness: shared demands on integration?2005Inngår i: Consciousness and Cognition, ISSN 1053-8100, E-ISSN 1090-2376, Vol. 14, nr 2, s. 390-425Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Fronto-parietal activity has been frequently observed in fMRI and PET studies of attention, working memory, and episodic memory retrieval. Several recent fMRI studies have also reported fronto-parietal activity during conscious visual perception. A major goal of this review was to assess the degree of anatomical overlap among activation patterns associated with these four functions. A second goal was to shed light on the possible cognitive relationship of processes that relate to common brain activity across functions. For all reviewed functions we observed a consistent and overlapping pattern of brain activity. The overlap was most pronounced for the bilateral parietal cortex (BA 7 and BA 40; close to the intraparietal sulcus), and dorsolateral prefrontal cortex (right BA 9 and left BA 6). The common fronto-parietal activity will be discussed in terms of processes related to integration of distributed representations in the brain.

  • 238. Naghavi, HR
    et al.
    Nyberg, Lars
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Common fronto-parietal activity in attention, memory, and consciousness: Shared demands on integration?2005Inngår i: CONSCIOUSNESS AND COGNITION, ISSN 1053-8100, Vol. 14, nr 2, s. 390-425Artikkel, forskningsoversikt (Annet (populærvitenskap, debatt, mm))
  • 239. Naghavi, HR
    et al.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Integrative action in the front-parietal network: A cure for a scattered mind2007Inngår i: Behavioral and Brain Sciences, ISSN 0140-525X, E-ISSN 1469-1825, Vol. 30, nr 2, s. 161-162Artikkel i tidsskrift (Fagfellevurdert)
  • 240. Nagi, Saad S.
    et al.
    Marshall, Andrew G.
    Makdani, Adarsh
    Jarocka, Ewa
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Liljencrantz, Jaquette
    Ridderstrom, Mikael
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Ortopedi.
    Shaikh, Sumaiya
    O'Neill, Francis
    Saade, Dimah
    Donkervoort, Sandra
    Foley, A. Reghan
    Minde, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Ortopedi.
    Trulsson, Mats
    Cole, Jonathan
    Bonnemann, Carsten G.
    Chesler, Alexander T.
    Bushnell, M. Catherine
    McGlone, Francis
    Olausson, Hakan
    An ultrafast system for signaling mechanical pain in human skin2019Inngår i: Science Advances, E-ISSN 2375-2548, Vol. 5, nr 7, artikkel-id eaaw1297Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The canonical view is that touch is signaled by fast-conducting, thickly myelinated afferents, whereas pain is signaled by slow-conducting, thinly myelinated (“fast” pain) or unmyelinated (“slow” pain) afferents. While other mammals have thickly myelinated afferents signaling pain (ultrafast nociceptors), these have not been demonstrated in humans. Here, we performed single-unit axonal recordings (microneurography) from cutaneous mechanoreceptive afferents in healthy participants. We identified A-fiber high-threshold mechanoreceptors (A-HTMRs) that were insensitive to gentle touch, encoded noxious skin indentations, and displayed conduction velocities similar to A-fiber low-threshold mechanoreceptors. Intraneural electrical stimulation of single ultrafast A-HTMRs evoked painful percepts. Testing in patients with selective deafferentation revealed impaired pain judgments to graded mechanical stimuli only when thickly myelinated fibers were absent. This function was preserved in patients with a loss-of-function mutation in mechanotransduction channel PIEZO2. These findings demonstrate that human mechanical pain does not require PIEZO2 and can be signaled by fast-conducting, thickly myelinated afferents.

    Fulltekst (pdf)
    fulltext
  • 241.
    Nevalainen, Nina
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Riklund, Katrine
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Andersson, Micael
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Axelsson, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Ögren, Mattias
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    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 universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    COBRA: A prospective multimodal imaging study of dopamine, brain structure and function, and cognition.2015Inngår i: Brain Research, ISSN 0006-8993, E-ISSN 1872-6240, Vol. 1612, s. 83-103Artikkel i tidsskrift (Fagfellevurdert)
    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.

    Fulltekst (pdf)
    fulltext
  • 242.
    Nilsson, Lars-Göran
    et al.
    Umeå universitet, Samhällsvetenskapliga fakulteten, Centrum för befolkningsstudier (CPS).
    Sternäng, Ola
    Department of Psychology, Stockholm University, Sweden.
    Rönnlund, Michael
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi. Umeå universitet, Samhällsvetenskapliga fakulteten, Centrum för befolkningsstudier (CPS).
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Samhällsvetenskapliga fakulteten, Centrum för befolkningsstudier (CPS).
    Challenging the notion of an early-onset of cognitive decline.2009Inngår i: Neurobiology of Aging, ISSN 0197-4580, E-ISSN 1558-1497, Vol. 30, nr 4, s. 521-524; discussion 530Artikkel i tidsskrift (Annet vitenskapelig)
    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.

  • 243.
    Nordin, Kristin
    et al.
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB). Umeå universitet, Medicinska fakulteten, Wallenberg centrum för molekylär medicin vid Umeå universitet (WCMM). Karolinska Instituet, Department of Neurobiology.
    Pedersen, Robin
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB). Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Medicinska fakulteten, Wallenberg centrum för molekylär medicin vid Umeå universitet (WCMM).
    Falahti, Farshad
    Karolinska Institutet, Department of Neurobiology.
    Johansson, Jarkko
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Grill, Filip
    Radbound University, Donders Center for Cognitive Neroimaging.
    Andersson, Micael
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB). Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Korkki, Saana
    Karolinska Institutet, Department of Neurobiology.
    Bäckman, Lars
    Karolinska Instiutet, Department of Neurobiology.
    Zalesky, Andrew
    University of Melbourne, Department of Biomedical Engineering.
    Rieckmann, Anna
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB). University of the Bundeswehr Munich, Department of Psychology.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Salami, Alireza
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB). Umeå universitet, Medicinska fakulteten, Wallenberg centrum för molekylär medicin vid Umeå universitet (WCMM). Karolinska Instiutet, Department of Neurobiology.
    Two long-axis dimensions of hippocampal cortical integration support memory functionacross the adult lifespanManuskript (preprint) (Annet vitenskapelig)
  • 244.
    Nordmark, Per F.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Handkirurgi.
    Structural and functional changes in the brain after surgically repaired median nerve injury2019Doktoravhandling, med artikler (Annet vitenskapelig)
    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.

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  • 245.
    Nordmark, Per F.
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Handkirurgi.
    Johansson, Roland S.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Disinhibition of human primary somatosensory cortex after median nerve transection and reinnervation2020Inngår i: Frontiers in Human Neuroscience, E-ISSN 1662-5161, Vol. 14, artikkel-id 166Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Despite state-of-the-art surgical and postoperative treatment, median nerve transection causes lasting impaired hand function due to limitations in the nerve’s reinnervation ability. The defective innervation and thus controllability of the affected hand can shape the brain’s control of manual behaviors. Earlier studies of changes in the processing of tactile stimuli have focused mainly on stimulation of the reinnervated hand and lack sufficient control over the brain’s use of the tactile input in perceptual terms. Here we used fMRI to measure brain activity (BOLD-signal) in 11 people with median nerve injury and healthy controls (N = 11) when performing demanding tactile tasks using the tip of either the index or little finger of either hand. For the nerve-injured group, the left median nerve had been traumatically transected in the distal forearm and surgically repaired on average 8 years before the study. The hand representation of their contralesional (right) primary somatosensory cortex (S1) showed greater activity compared to controls when the left reinnervated index finger was used, but also when the left-hand little finger and the fingers of the right hand innervated by uninjured nerves were used. We argue that the overall increase in activity reflects a general disinhibition of contralesional S1 consistent with an augmented functional reorganizational plasticity being an ongoing feature of chronic recovery from nerve injury. Also, the nerve-injured showed increased activity within three prefrontal cortical areas implicated in higher-level behavioral processing (dorsal anterior cingulate cortex, left ventrolateral prefrontal and right dorsolateral prefrontal cortex), suggesting that processes supporting decision-making and response-selection were computationally more demanding due to the compromised tactile sensibility.

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  • 246.
    Nordmark, Per F.
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Handkirurgi.
    Ljungberg, Christina
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Handkirurgi.
    Johansson, Roland S.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Structural changes in hand related cortical areas after median nerve injury and repair2018Inngår i: Scientific Reports, E-ISSN 2045-2322, Vol. 8, artikkel-id 4485Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Transection of the median nerve typically causes lifelong restriction of fine sensory and motor skills of the affected hand despite the best available surgical treatment. Inspired by recent findings on activity-dependent structural plasticity of the adult brain, we used voxel-based morphometry to analyze the brains of 16 right-handed adults who more than two years earlier had suffered injury to the left or right median nerve followed by microsurgical repair. Healthy individuals served as matched controls. Irrespective of side of injury, we observed gray matter reductions in left ventral and right dorsal premotor cortex, and white matter reductions in commissural pathways interconnecting those motor areas. Only left-side injured participants showed gray matter reduction in the hand area of the contralesional primary motor cortex. We interpret these effects as structural manifestations of reduced neural processing linked to restrictions in the diversity of the natural manual dexterity repertoire. Furthermore, irrespective of side of injury, we observed gray matter increases bilaterally in a motion-processing visual area. We interpret this finding as a consequence of increased neural processing linked to greater dependence on vision for control of manual dexterity after median nerve injury because of a compromised somatosensory innervation of the affected hand.

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  • 247.
    Nordmark, Per F.
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Pruszynski, J. Andrew
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Johansson, Roland S.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    BOLD Responses to Tactile Stimuli in Visual and Auditory Cortex Depend on the Frequency Content of Stimulation2012Inngår i: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 24, nr 10, s. 2120-2134Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Although some brain areas preferentially process information from a particular sensory modality, these areas can also respond to other modalities. Here we used fMRI to show that such responsiveness to tactile stimuli depends on the temporal frequency of stimulation. Participants performed a tactile threshold-tracking task where the tip of either their left or right middle finger was stimulated at 3, 20, or 100 Hz. Whole-brain analysis revealed an effect of stimulus frequency in two regions: the auditory cortex and the visual cortex. The BOLD response in the auditory cortex was stronger during stimulation at hearable frequencies (20 and 100 Hz) whereas the response in the visual cortex was suppressed at infrasonic frequencies (3 Hz). Regardless of which hand was stimulated, the frequency-dependent effects were lateralized to the left auditory cortex and the right visual cortex. Furthermore, the frequency-dependent effects in both areas were abolished when the participants performed a visual task while receiving identical tactile stimulation as in the tactile threshold-tracking task. We interpret these findings in the context of the metamodal theory of brain function, which posits that brain areas contribute to sensory processing by performing specific computations regardless of input modality.

  • 248.
    Nordström, Anna
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Rehabiliteringsmedicin. Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Edin, Benoni B.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Lindström, Sara
    Nordström, Peter
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Geriatrik.
    Cognitive function and other risk factors for mild traumatic brain injury in young men: nationwide cohort study2013Inngår i: The BMJ, E-ISSN 1756-1833, Vol. 346, s. f723-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objective To investigate cognitive function and other risk factors for mild traumatic brain injury in young men.

    Design Nationwide prospective cohort study.

    Setting Sweden.

    Participants 305 885 men conscripted for military service from 1989 to 1994.

    Main outcome measure mild traumatic brain injuries in relation to cognitive function and other potential risk factors assessed at conscription and follow-up.

    Results Men with one mild traumatic brain injury within two years before (n=1988) or after cognitive testing (n=2214) had about 5.5% lower overall cognitive function scores than did men with no mild traumatic brain injury during follow up (P<0.001 for both). Moreover, men with at least two mild traumatic brain injuries after cognitive testing (n=795) had 15% lower overall cognitive function scores compared with those with no such injury (P<0.001). Independent strong risk factors (P<1x10(-10)) for at least one mild traumatic brain injury after cognitive testing (n=12 494 events) included low overall cognitive function, a previous mild traumatic brain injury, hospital admission for intoxications, and low education and socioeconomic status. In a sub-cohort of twin pairs in which one twin had a mild traumatic brain injury before cognitive testing (n=63), both twins had lower logical performance and technical performance compared with men in the total cohort with no mild traumatic brain injury (P<0.05 for all).

    Conclusion Low cognitive function, intoxications, and factors related to low socioeconomic status were strong independent risk factors for mild traumatic brain injuries in men. The low cognitive function in twin pairs discordant for mild traumatic brain injury suggests a genetic component to the low cognitive function associated with such injuries. The study included only men, so inferences to women should be made with caution.

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    Cognitive function and other risk factors for mild traumatic brain injury in young men: nationwide cohort study
  • 249.
    Nyberg, Lars
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Fysiologi.
    Den anpassningsbara hjärnan2004Inngår i: Stroke - ett slag mot hjärnan: Forskningens dag 2004, Medicinska fakulteten, Umeå , 2004, s. 37-45Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 250.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Functional imaging studies of intentional and incidental reactiviation: Implications for the bidning problem2006Inngår i: Handbook of binding and memory: Perspective from cognitive neuroscience, Oxford: Oxford University Press , 2006, s. 493-515Kapittel i bok, del av antologi (Annet (populærvitenskap, debatt, mm))
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