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Awad, A., Grill, F., Blomstedt, P., Nyberg, L. & Eriksson, J. (2024). Deep brain stimulation does not modulate resting-state functional connectivity in essential tremor. Brain Communications, 6(2), Article ID fcae012.
Open this publication in new window or tab >>Deep brain stimulation does not modulate resting-state functional connectivity in essential tremor
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2024 (English)In: Brain Communications, E-ISSN 2632-1297, Vol. 6, no 2, article id fcae012Article in journal (Refereed) Published
Abstract [en]

While the effectiveness of deep brain stimulation in alleviating essential tremor is well-established, the underlying mechanisms of the treatment are unclear. Essential tremor, as characterized by tremor during action, is proposed to be driven by a dysfunction in the cerebello-thalamo-cerebral circuit that is evident not only during motor actions but also during rest. Stimulation effects on resting-state functional connectivity were investigated by functional MRI in 16 essential tremor patients with fully implanted deep brain stimulation in the caudal zona incerta during On-and-Off therapeutic stimulation, in a counterbalanced design. Functional connectivity was calculated between different constellations of sensorimotor as well as non-sensorimotor regions (as derived from seed-based and data-driven approaches), and compared between On and Off stimulation. We found that deep brain stimulation did not modulate resting-state functional connectivity. The lack of modulation by deep brain stimulation during resting-state, in combination with previously demonstrated effects on the cerebello-thalamo-cerebral circuit during motor tasks, suggests an action-dependent modulation of the stimulation in essential tremor.

Place, publisher, year, edition, pages
Oxford University Press, 2024
Keywords
caudal zona incerta, deep brain stimulation, essential tremor, functional connectivity, resting-state fMRI
National Category
Neurology
Identifiers
urn:nbn:se:umu:diva-222642 (URN)10.1093/braincomms/fcae012 (DOI)001184993600003 ()38482375 (PubMedID)2-s2.0-85188020052 (Scopus ID)
Funder
Knut and Alice Wallenberg FoundationRegion Västerbotten
Available from: 2024-04-19 Created: 2024-04-19 Last updated: 2024-04-19Bibliographically approved
Simistira Liwicki, F., Gupta, V., Saini, R., De, K., Abid, N., Rakesh, S., . . . Eriksson, J. (2023). Bimodal electroencephalography-functional magnetic resonance imaging dataset for inner-speech recognition. Scientific Data, 10(1), Article ID 378.
Open this publication in new window or tab >>Bimodal electroencephalography-functional magnetic resonance imaging dataset for inner-speech recognition
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2023 (English)In: Scientific Data, E-ISSN 2052-4463, Vol. 10, no 1, article id 378Article in journal (Refereed) Published
Abstract [en]

The recognition of inner speech, which could give a ‘voice’ to patients that have no ability to speak or move, is a challenge for brain-computer interfaces (BCIs). A shortcoming of the available datasets is that they do not combine modalities to increase the performance of inner speech recognition. Multimodal datasets of brain data enable the fusion of neuroimaging modalities with complimentary properties, such as the high spatial resolution of functional magnetic resonance imaging (fMRI) and the temporal resolution of electroencephalography (EEG), and therefore are promising for decoding inner speech. This paper presents the first publicly available bimodal dataset containing EEG and fMRI data acquired nonsimultaneously during inner-speech production. Data were obtained from four healthy, right-handed participants during an inner-speech task with words in either a social or numerical category. Each of the 8-word stimuli were assessed with 40 trials, resulting in 320 trials in each modality for each participant. The aim of this work is to provide a publicly available bimodal dataset on inner speech, contributing towards speech prostheses.

Place, publisher, year, edition, pages
Springer Nature, 2023
National Category
Language Technology (Computational Linguistics) Neurosciences Medical Image Processing
Identifiers
urn:nbn:se:umu:diva-211406 (URN)10.1038/s41597-023-02286-w (DOI)001006100600001 ()37311807 (PubMedID)2-s2.0-85161923014 (Scopus ID)
Available from: 2023-07-11 Created: 2023-07-11 Last updated: 2023-07-11Bibliographically approved
Philipson, J., Awad, A., Lindström, L., Blomstedt, P., Jahanshahi, M. & Eriksson, J. (2023). Evaluation of the effects of DBS in the caudal Zona incerta on brain activity during a working memory task in patients with essential tremor. Neuroimage: Reports, 3(4), Article ID 100193.
Open this publication in new window or tab >>Evaluation of the effects of DBS in the caudal Zona incerta on brain activity during a working memory task in patients with essential tremor
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2023 (English)In: Neuroimage: Reports, ISSN 2666-9560, Vol. 3, no 4, article id 100193Article in journal (Refereed) Published
Abstract [en]

Essential tremor (ET) is characterized by bilateral upper limb postural and/or kinetic tremor, but also cognitive deficits. Tremor in ET, as well as aspects of cognitive deficits associated with ET, have been suggested to be linked to dysfunction in the cerebello-thalamo-cerebral circuit. In ET patients with disabling and medically intractable motor symptoms, Deep Brain Stimulation (DBS) is effective in reducing tremor. DBS in the caudal Zona incerta (cZi) has been shown to modulate the activity of the sensorimotor cerebello-cerebral circuit during motor tasks. Whether the activity in the cerebello-cerebral circuit is modulated by DBS during tasks involving working memory is unknown. The present study therefore aimed to investigate the possible effects of cZi DBS on working-memory processing in ET patients by means of task-based blood oxygen level-dependent (BOLD) fMRI.

Thirteen ET patients completed a working-memory task during DBS OFF and ON conditions. The task involved three conditions: maintenance, manipulation, and control. Behaviorally, there was no significant effect from DBS on accuracy, but a marginally significant Task x DBS interaction was detected for response times (RTs). However, post hoc comparisons for each condition failed to reach statistical significance. FMRI analyses revealed that DBS did not alter BOLD signal in regions of interest (lateral prefrontal cortex, parietal cortex, and the cerebellum), or in a complementary whole-brain analysis.

The present study indicates that DBS in the cZi in patients with ET has at most marginal effects on working memory, which is consistent with the results of pre- and post-DBS neuropsychological assessment showing minimal cognitive effects of surgery.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Deep brain stimulation, Essential tremor, Working memory, fMRI
National Category
Neurosciences
Research subject
Neurology
Identifiers
urn:nbn:se:umu:diva-204363 (URN)10.1016/j.ynirp.2023.100193 (DOI)2-s2.0-85175237822 (Scopus ID)
Funder
Swedish Research Council
Note

Originally included in thesis in manuscript form.

Available from: 2023-02-02 Created: 2023-02-02 Last updated: 2023-11-09Bibliographically approved
Eriksson, J., Nyberg, L., Elgh, E. & Hu, X.-L. (2023). Improvement of cognition across a decade after stroke correlates with the integrity of functional brain networks. NeuroImage: Clinical, 37, Article ID 103356.
Open this publication in new window or tab >>Improvement of cognition across a decade after stroke correlates with the integrity of functional brain networks
2023 (English)In: NeuroImage: Clinical, E-ISSN 2213-1582, Vol. 37, article id 103356Article in journal (Refereed) Published
Abstract [en]

Background and objective: We recently reported improvements of working memory across 10 years post stroke among middle-aged individuals. However, the mechanisms underlying working-memory recovery are largely unknown. This study investigated the associations between long-term improvement of working memory and resting-state functional connectivity in two frontoparietal networks: the frontoparietal network and the dorsal attention network.

Methods: Working memory was repeatedly assessed by the Digit Span Backwards task in 21 persons, within 1 year after stroke onset and again 10 years post stroke onset. Brain functional connectivity was examined by resting state functional magnetic resonance imaging at the 10-year follow-up.

Results: A significant improvement of working memory was found among 21 persons after stroke (median age = 64) at the 10-year follow-up compared to the within-one-year assessment. The magnitude of performance improvement on the Digit Span Backwards task was significantly positively correlated with stronger brain connectivity in the frontoparietal network (r = 0.51, p = 0.018) measured at the 10-year follow-up only. A similar association was observed in the dorsal attention network (r = 0.43, p = 0.052) but not in a visual network (r = -0.17, p = 0.46) that served as a control network. The association between functional connectivity within the above-mentioned networks and Digit Span Backwards scores at 10-year after stroke was in the same direction but did not reach significance.

Conclusions: The present work relate stronger long-term performance improvement on the Digit Span Backwards task with higher integrity of frontoparietal network connectivity.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Cognitive improvement, Functional connectivity, Long-term, Stroke, Working memory
National Category
Neurosciences Neurology
Identifiers
urn:nbn:se:umu:diva-205503 (URN)10.1016/j.nicl.2023.103356 (DOI)000975416600001 ()36842348 (PubMedID)2-s2.0-85148731680 (Scopus ID)
Funder
The Swedish Stroke AssociationRegion VästerbottenUmeå UniversityKnut and Alice Wallenberg Foundation
Available from: 2023-03-14 Created: 2023-03-14 Last updated: 2024-01-17Bibliographically approved
Pedale, T., Fontan, A., Grill, F., Bergström, F. & Eriksson, J. (2023). Nonconscious information can be identified as task-relevant but not prioritized in working memory. Cerebral Cortex, 33(5), 2287-2301
Open this publication in new window or tab >>Nonconscious information can be identified as task-relevant but not prioritized in working memory
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2023 (English)In: Cerebral Cortex, ISSN 1047-3211, E-ISSN 1460-2199, Vol. 33, no 5, p. 2287-2301Article in journal (Refereed) Published
Abstract [en]

Two critical features of working memory are the identification and appropriate use of task-relevant information while avoiding distraction. Here, in 3 experiments, we explored if these features can be achieved also for nonconscious stimuli. Participants performed a delayed match-to-sample task in which task relevance of 2 competing stimuli was indicated by a cue, and continuous flash suppression was used to manipulate the conscious/nonconscious visual experience. Experiment 1 revealed better-than-chance performance with nonconscious stimuli, demonstrating goal-directed use of nonconscious task-relevant information. Experiment 2 demonstrated that the cue that defined task relevance must be conscious to allow such goal-directed use. In Experiment 3, multi-voxel pattern analyses of brain activity revealed that only the target was prioritized and maintained during conscious trials. Conversely, during nonconscious trials, both target and distractor were maintained. However, decoding of task relevance during the probe/test phase demonstrated identification of both target and distractor information. These results show that identification of task-relevant information can operate also on nonconscious material. However, they do not support the prioritization of nonconscious task-relevant information, thus suggesting a mismatch in the attentional mechanisms involved during conscious and nonconscious working memory.

Place, publisher, year, edition, pages
Oxford University Press, 2023
Keywords
attention, consciousness, distraction, endogenous control, fMRI
National Category
Neurosciences
Research subject
Physiology
Identifiers
urn:nbn:se:umu:diva-206443 (URN)10.1093/cercor/bhac208 (DOI)000806494600001 ()35667703 (PubMedID)2-s2.0-85165940151 (Scopus ID)
Funder
Swedish Research Council, 2016-02931
Available from: 2023-04-05 Created: 2023-04-05 Last updated: 2023-09-06Bibliographically approved
Fontan, A., Lindgren, L., Pedale, T., Brorsson, C., Bergström, F. & Eriksson, J. (2021). A reduced level of consciousness affects non-conscious processes. NeuroImage, 244, Article ID 118571.
Open this publication in new window or tab >>A reduced level of consciousness affects non-conscious processes
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2021 (English)In: NeuroImage, ISSN 1053-8119, E-ISSN 1095-9572, Vol. 244, article id 118571Article in journal (Refereed) Published
Abstract [en]

Being conscious is a profound aspect of human existence, and understanding its function and its inception is considered one of the truly grand scientific challenges. However, the nature of consciousness remains enigmatic, to a large part because “being conscious” can refer to both the content (phenomenology) and the level (arousal) of consciousness, and how these different aspects are related remains unclear. To empirically assess the relation between level and content of consciousness, we manipulated these two aspects by presenting stimuli consciously or non-consciously and by using Propofol sedation, while brain activity was measured using fMRI. We observed that sedation affected both conscious and non-conscious processes but at different hierarchical levels; while conscious processing was altered in higher-order regions (the intraparietal sulcus) and spared sensory areas, the opposite effect was observed for non-conscious processing. The observation that Propofol affected non-conscious processing calls for a reconsideration of what kind of information one can gain on “consciousness” from recording neural responses to sedation without considering both (content) conscious and (content) non-conscious processing.

Place, publisher, year, edition, pages
Elsevier, 2021
Keywords
Brain activity, Consciousness, fMRI, Sedation, Unconscious
National Category
Neurosciences
Identifiers
urn:nbn:se:umu:diva-187741 (URN)10.1016/j.neuroimage.2021.118571 (DOI)000696967000002 ()34509624 (PubMedID)2-s2.0-85114794464 (Scopus ID)
Funder
Riksbankens Jubileumsfond, P17-0772:1
Available from: 2021-09-28 Created: 2021-09-28 Last updated: 2023-05-02Bibliographically approved
Awad, A., Blomstedt, P., Westling, G. & Eriksson, J. (2020). Deep brain stimulation in the caudal zona incerta modulates the sensorimotor cerebello-cerebral circuit in essential tremor. NeuroImage, 209, Article ID 116511.
Open this publication in new window or tab >>Deep brain stimulation in the caudal zona incerta modulates the sensorimotor cerebello-cerebral circuit in essential tremor
2020 (English)In: NeuroImage, ISSN 1053-8119, E-ISSN 1095-9572, Vol. 209, article id 116511Article in journal (Refereed) Published
Abstract [en]

Essential tremor is effectively treated with deep brain stimulation (DBS), but the neural mechanisms underlying the treatment effect are poorly understood. Essential tremor is driven by a dysfunctional cerebello-thalamo-cerebral circuit resulting in pathological tremor oscillations. DBS is hypothesised to interfere with these oscillations at the stimulated target level, but it is unknown whether the stimulation modulates the activity of the cerebello-thalamo-cerebral circuit during different task states (with and without tremor) in awake essential tremor patients. To address this issue, we used functional MRI in 16 essential tremor patients chronically implanted with DBS in the caudal zona incerta. During scanning, the patients performed unilateral tremor-inducing postural holding and pointing tasks as well as rest, with contralateral stimulation turned On and Off.

We show that DBS exerts both task-dependent as well as task-independent modulation of the sensorimotor cerebello-cerebral regions (p ​≤ ​0.05, FWE cluster-corrected for multiple comparisons). Task-dependent modulation (DBS ​× ​task interaction) resulted in two patterns of stimulation effects. Firstly, activity decreases (blood oxygen level-dependent signal) during tremor-inducing postural holding in the primary sensorimotor cortex and cerebellar lobule VIII, and activity increases in the supplementary motor area and cerebellar lobule V during rest (p ​≤ ​0.05, post hoc two-tailed t-test). These effects represent differences at the effector level and may reflect DBS-induced tremor reduction since the primary sensorimotor cortex, cerebellum and supplementary motor area exhibit less motor task-activity as compared to the resting condition during On stimulation. Secondly, task-independent modulation (main effect of DBS) was observed as activity increase in the lateral premotor cortex during all motor tasks, and also during rest (p ​≤ ​0.05, post hoc two-tailed t-test). This task-independent effect may mediate the therapeutic effects of DBS through the facilitation of the premotor control over the sensorimotor circuit, making it less susceptible to tremor entrainment.

Our findings support the notion that DBS in essential tremor is modulating the sensorimotor cerebello-cerebral circuit, distant to the stimulated target, and illustrate the complexity of stimulation mechanisms by demonstrating task-dependent as well as task-independent actions in cerebello-cerebral regions.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Essential tremor, Deep brain stimulation, Caudal zona incerta, Functional MRI, Cerebello-cerebral circuit
National Category
Neurology Physiology Neurosciences
Research subject
Neurosurgery; Neurology; Physiology
Identifiers
urn:nbn:se:umu:diva-167200 (URN)10.1016/j.neuroimage.2019.116511 (DOI)000517885100011 ()31901420 (PubMedID)2-s2.0-85077302888 (Scopus ID)
Funder
Västerbotten County Council
Available from: 2020-01-11 Created: 2020-01-11 Last updated: 2023-03-24Bibliographically approved
Eriksson, J., Fontan, A. & Pedale, T. (2020). Make the Unconscious Explicit to Boost the Science of Consciousness. Frontiers in Psychology, 11, Article ID 260.
Open this publication in new window or tab >>Make the Unconscious Explicit to Boost the Science of Consciousness
2020 (English)In: Frontiers in Psychology, E-ISSN 1664-1078, Vol. 11, article id 260Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Frontiers Media S.A., 2020
Keywords
consciousness, unconscious, false negative, neural correlates of consciousness, high-level cognition
National Category
Psychology (excluding Applied Psychology)
Identifiers
urn:nbn:se:umu:diva-169045 (URN)10.3389/fpsyg.2020.00260 (DOI)000519066200001 ()32140132 (PubMedID)2-s2.0-85081693921 (Scopus ID)
Available from: 2020-03-19 Created: 2020-03-19 Last updated: 2023-03-24Bibliographically approved
Andersson, L., Eriksson, J., Stillesjö, S., Juslin, P., Nyberg, L. & Karlsson Wirebring, L. (2020). Neurocognitive processes underlying heuristic and normative probability judgments. Cognition, 196, 1-7, Article ID 104153.
Open this publication in new window or tab >>Neurocognitive processes underlying heuristic and normative probability judgments
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2020 (English)In: Cognition, ISSN 0010-0277, E-ISSN 1873-7838, Vol. 196, p. 1-7, article id 104153Article in journal (Refereed) Published
Abstract [en]

Judging two events in combination (A&B) as more probable than one of the events (A) is known as a conjunction fallacy. According to dual-process explanations of human judgment and decision making, the fallacy is due to the application of a heuristic, associative cognitive process. Avoiding the fallacy has been suggested to require the recruitment of a separate process that can apply normative rules. We investigated these assumptions using functional magnetic resonance imaging (fMRI) during conjunction tasks. Judgments, whether correct or not, engaged a network of brain regions identical to that engaged during similarity judgments. Avoidance of the conjunction fallacy additionally, and uniquely, involved a fronto-parietal network previously linked to supervisory, analytic control processes. The results lend credibility to the idea that incorrect probability judgments are the result of a representativeness heuristic that requires additional neurocognitive resources to avoid.

Place, publisher, year, edition, pages
ELSEVIER, 2020
Keywords
Decision making, Dual-system, Dual-process, fMRI, Representativeness
National Category
Philosophy
Identifiers
urn:nbn:se:umu:diva-169341 (URN)10.1016/j.cognition.2019.104153 (DOI)000518704700021 ()31838247 (PubMedID)2-s2.0-85076262700 (Scopus ID)
Projects
ujl
Available from: 2020-04-15 Created: 2020-04-15 Last updated: 2023-12-14Bibliographically approved
Awad, A., Levi, R., Waller, M., Westling, G., Lindgren, L. & Eriksson, J. (2020). Preserved somatosensory conduction in complete spinal cord injury: Discomplete SCI. Clinical Neurophysiology, 131(5), 1059-1067
Open this publication in new window or tab >>Preserved somatosensory conduction in complete spinal cord injury: Discomplete SCI
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2020 (English)In: Clinical Neurophysiology, ISSN 1388-2457, E-ISSN 1872-8952, Vol. 131, no 5, p. 1059-1067Article in journal (Refereed) Published
Abstract [en]

Objective: Spinal cord injury (SCI) disrupts the communication between brain and body parts innervated from below-injury spinal segments, but rarely results in complete anatomical transection of the spinal cord. The aim of this study was to investigate residual somatosensory conduction in clinically complete SCI, to corroborate the concept of sensory discomplete SCI.

Methods: We used fMRI with a somatosensory protocol in which blinded and randomized tactile and nociceptive stimulation was applied on both legs (below-injury level) and one arm (above-injury level) in eleven participants with chronic complete SCI. The experimental design accounts for possible confounding mechanical (e.g. vibration) and cortico-cortical top-down mechanisms (e.g. attention/expectation).

Results: Somatosensory stimulation on below-level insensate body regions activated the somatotopically corresponding part of the contralateral primary somatosensory cortex in six out of eleven participants.

Conclusions: Our results represent afferent-driven cortical activation through preserved somatosensory connections to the brain in a subgroup of participants with clinically complete SCI, i.e. sensory discomplete SCI.

Significance: Identifying patients with residual somatosensory connections might open the door for new rehabilitative and restorative strategies as well as inform research on SCI-related conditions such as neuropathic pain and spasticity.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Spinal cord injury, Functional MRI, Somatosensory, Discomplete, Non-conscious
National Category
Neurology Neurosciences Physiology
Research subject
Neurology; Neurosurgery; Rehabilitation Medicine; Physiology
Identifiers
urn:nbn:se:umu:diva-169138 (URN)10.1016/j.clinph.2020.01.017 (DOI)000525862400011 ()32197128 (PubMedID)2-s2.0-85082123930 (Scopus ID)
Available from: 2020-03-22 Created: 2020-03-22 Last updated: 2022-07-15Bibliographically approved
Projects
Memory and Consciousness - Neurophysiological investigations of conscious and unconscious memory processes [2012-01232_VR]; Umeå UniversityThe silent side of working memory [2016-02931_VR]; Umeå UniversityHow global mental states affect consciousness ? a neurobiologial perspective [P17-0772:1_RJ]; Umeå University
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-1407-9288

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