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Author Frenkel-Toledo, S.; Liebermann, D.G.; Bentin, S.; Soroker, N.
Title Dysfunction of the Human Mirror Neuron System in Ideomotor Apraxia: Evidence from Mu Suppression Type Journal Article
Year 2016 Publication Journal of Cognitive Neuroscience Abbreviated Journal J Cogn Neurosci
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Abstract Stroke patients with ideomotor apraxia (IMA) have difficulties controlling voluntary motor actions, as clearly seen when asked to imitate simple gestures performed by the examiner. Despite extensive research, the neurophysiological mechanisms underlying failure to imitate gestures in IMA remain controversial. The aim of the current study was to explore the relationship between imitation failure in IMA and mirror neuron system (MNS) functioning. Mirror neurons were found to play a crucial role in movement imitation and in imitation-based motor learning. Their recruitment during movement observation and execution is signaled in EEG recording by suppression of the lower (8-10 Hz) mu range. We examined the modulation of EEG in this range in stroke patients with left (n = 21) and right (n = 15) hemisphere damage during observation of video clips showing different manual movements. IMA severity was assessed by the DeRenzi's standardized diagnostic test. Results showed that failure to imitate observed manual movements correlated with diminished mu suppression in patients with damage to the right inferior parietal lobule and in patients with damage to the right inferior frontal gyrus pars opercularis-areas where major components of the human MNS are assumed to reside. Voxel-based lesion symptom mapping revealed a significant impact on imitation capacity for the left inferior and superior parietal lobules and the left post central gyrus. Both left and right hemisphere damages were associated with imitation failure typical of IMA, yet a clear demonstration of relationship to the MNS was obtained only in the right hemisphere damage group. Suppression of the 8-10 Hz range was stronger in central compared with occipital sites, pointing to a dominant implication of mu rather than alpha rhythms. However, the suppression correlated with De Renzi's apraxia test scores not only in central but also in occipital sites, suggesting a multifactorial mechanism for IMA, with a possible impact for deranged visual attention (alpha suppression) beyond the effect of MNS damage (mu suppression).
Address Loewenstein Hospital, Ra'anana, Israel
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Language English Summary Language Original Title
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ISSN 0898-929X ISBN Medium
Area Expedition Conference
Notes PMID:26942323 Approved no
Call Number Serial 82
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Author Banina, M.C.; Molad, R.; Solomon, J.S.; Berman, S.; Soroker, N.; Frenkel-Toledo, S.; Liebermann, D.G.; Levin, M.F.
Title Exercise intensity of the upper limb can be enhanced using a virtual rehabilitation system Type Journal Article
Year 2020 Publication Disability and Rehabilitation. Assistive Technology Abbreviated Journal Disabil Rehabil Assist Technol
Volume Issue (down) Pages 1-7
Keywords Stroke; difficulty; exercise therapy; intensity; personalized exercise; upper limb; virtual reality
Abstract Purpose: Motor recovery of the upper limb (UL) is related to exercise intensity, defined as movement repetitions divided by minutes in active therapy, and task difficulty. However, the degree to which UL training in virtual reality (VR) applications deliver intense and challenging exercise and whether these factors are considered in different centres for people with different sensorimotor impairment levels is not evidenced. We determined if (1) a VR programme can deliver high UL exercise intensity in people with sub-acute stroke across different environments and (2) exercise intensity and difficulty differed among patients with different levels of UL sensorimotor impairment.Methods: Participants with sub-acute stroke (<6 months) with Fugl-Meyer scores ranging from 14 to 57, completed 10 approximately 50-min UL training sessions using three unilateral and one bilateral VR activity over 2 weeks in centres located in three countries. Training time, number of movement repetitions, and success rates were extracted from game activity logs. Exercise intensity was calculated for each participant, related to UL impairment, and compared between centres.Results: Exercise intensity was high and was progressed similarly in all centres. Participants had most difficulty with bilateral and lateral reaching activities. Exercise intensity was not, while success rate of only one unilateral activity was related to UL severity.Conclusion: The level of intensity attained with this VR exercise programme was higher than that reported in current stroke therapy practice. Although progression through different activity levels was similar between centres, clearer guidelines for exercise progression should be provided by the VR application.Implications for rehabilitationVR rehabilitation systems can be used to deliver intensive exercise programmes.VR rehabilitation systems need to be designed with measurable progressions through difficulty levels.
Address Center for Interdisciplinary Research in Rehabilitation of Greater Montreal (CRIR), Feil and Oberfeld Research Centre, Jewish Rehabilitation Hospital, Laval, Canada
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Language English Summary Language Original Title
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Series Volume Series Issue Edition
ISSN 1748-3107 ISBN Medium
Area Expedition Conference
Notes PMID:32421460 Approved no
Call Number Serial 106
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Author Markstrom, J.L.; Liebermann, D.G.; Schelin, L.; Hager, C.K.
Title Atypical Lower Limb Mechanics During Weight Acceptance of Stair Descent at Different Time Frames After Anterior Cruciate Ligament Reconstruction Type Journal Article
Year 2022 Publication The American Journal of Sports Medicine Abbreviated Journal Am J Sports Med
Volume Issue (down) Pages 1-9
Keywords Acl; biomechanics; functional data analysis; motion analysis; stepping down
Abstract BACKGROUND: An anterior cruciate ligament (ACL) rupture may result in poor sensorimotor knee control and, consequentially, adapted movement strategies to help maintain knee stability. Whether patients display atypical lower limb mechanics during weight acceptance of stair descent at different time frames after ACL reconstruction (ACLR) is unknown. PURPOSE: To compare the presence of atypical lower limb mechanics during the weight acceptance phase of stair descent among athletes at early, middle, and late time frames after unilateral ACLR. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 49 athletes with ACLR were classified into 3 groups according to time after ACLR-early (<6 months; n = 17), middle (6-18 months; n = 16), and late (>18 months; n = 16)-and compared with asymptomatic athletes (control; n = 18). Sagittal plane hip, knee, and ankle angles; angular velocities; moments; and powers were compared between the ACLR groups' injured and noninjured legs and the control group as well as between legs within groups using functional data analysis methods. RESULTS: All 3 ACLR groups showed greater knee flexion angles and moments than the control group for injured and noninjured legs. For the other outcomes, the early group had, compared with the control group, less hip power absorption, more knee power absorption, lower ankle plantarflexion angle, lower ankle dorsiflexion moment, and less ankle power absorption for the injured leg and more knee power absorption and higher vertical ground reaction force for the noninjured leg. In addition, the late group showed differences from the control group for the injured leg revealing more knee power absorption and lower ankle plantarflexion angle. Only the early group took a longer time than the control group to complete weight acceptance and demonstrated asymmetry for multiple outcomes. CONCLUSION: Athletes with different time frames after ACLR revealed atypically large knee angles and moments during weight acceptance of stair descent for both the injured and the noninjured legs. These findings may express a chronically adapted strategy to increase knee control. In contrast, atypical hip and ankle mechanics seem restricted to an early time frame after ACLR. CLINICAL RELEVANCE: Rehabilitation after ACLR should include early training in controlling weight acceptance. Including a control group is essential when evaluating movement patterns after ACLR because both legs may be affected.
Address Department of Community Medicine and Rehabilitation, Physiotherapy, Umea University, Umea, Sweden
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Language English Summary Language Original Title
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Series Volume Series Issue Edition
ISSN 0363-5465 ISBN Medium
Area Expedition Conference
Notes PMID:35604127 Approved no
Call Number Serial 112
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Author Grinberg, A.; Strong, A.; Strandberg, J.; Selling, J.; Liebermann, D.G.; Bjorklund, M.; Hager, C.K.
Title Electrocortical activity associated with movement-related fear: a methodological exploration of a threat-conditioning paradigm involving destabilising perturbations during quiet standing Type Journal Article
Year 2024 Publication Experimental Brain Research Abbreviated Journal Exp Brain Res
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Keywords Cnv; Eeg; Erp; Kinesiophobia; Moving platform; Re-injury anxiety
Abstract Musculoskeletal trauma often leads to lasting psychological impacts stemming from concerns of future injuries. Often referred to as kinesiophobia or re-injury anxiety, such concerns have been shown to hinder return to physical activity and are believed to increase the risk for secondary injuries. Screening for re-injury anxiety is currently restricted to subjective questionnaires, which are prone to self-report bias. We introduce a novel approach to objectively identify electrocortical activity associated with the threat of destabilising perturbations. We aimed to explore its feasibility among non-injured persons, with potential future implementation for screening of re-injury anxiety. Twenty-three participants stood blindfolded on a translational balance perturbation platform. Consecutive auditory stimuli were provided as low (neutral stimulus [CS(-)]) or high (conditioned stimulus [CS(+)]) tones. For the main experimental protocol (Protocol I), half of the high tones were followed by a perturbation in one of eight unpredictable directions. A separate validation protocol (Protocol II) requiring voluntary squatting without perturbations was performed with 12 participants. Event-related potentials (ERP) were computed from electroencephalography recordings and significant time-domain components were detected using an interval-wise testing procedure. High-amplitude early contingent negative variation (CNV) waves were significantly greater for CS(+) compared with CS(-) trials in all channels for Protocol I (> 521-800ms), most prominently over frontal and central midline locations (P </= 0.001). For Protocol II, shorter frontal ERP components were observed (541-609ms). Our test paradigm revealed electrocortical activation possibly associated with movement-related fear. Exploring the discriminative validity of the paradigm among individuals with and without self-reported re-injury anxiety is warranted.
Address Department of Community Medicine and Rehabilitation, Umea University, Umea, Sweden
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Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0014-4819 ISBN Medium
Area Expedition Conference
Notes PMID:38896295 Approved no
Call Number Serial 122
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