The Neural Correlates of Bilateral Arm Movements in Stroke

  • Pei Ling Choo

Student thesis: Doctoral ThesisDoctor of Philosophy (PhD)

Abstract

Bilateral upper limb training (BT) has rehabilitation potential in improving upper limb (UL) function after stroke. To capitalise on the therapeutic potential of BT, the thesis aimed to understand the mechanisms of action underlying different modes of BT at the cortical and behavioural levels in acute stroke survivors. First, a systematic review was conducted to synthesise published literature on the correlates of UL motor behaviour and brain activation following BT after stroke(chapter 2). No clear pattern of motor behaviour and brain activation in response to BT was apparent and synthesis of the evidence was hampered by the wide diversity in the delivery of BT.

Next, a cross-sectional cohort study was undertaken to compare the effects of unilateral and bilateral task modes on patterns of UL intralimb kinematics, interlimb coordination and brain activation in healthy individuals. This pilot study i) provided a reference prior to examining the stroke population and ii) tested the kinematic assessments and fMRI paradigm for feasibility before use with the stroke population (chapter 3). In the healthy participants (chapter 4), both the non-dominant and dominant arms displayed no significant difference in any of the intralimb kinematic measures between a unilateral, bilateral in-phase and bilateral anti-phase mode of performing a discrete grasp task. Coordination stability (although not significant) was higher and phase error was smaller during bilateralin-phase than bilateral anti-phase wrist flexion-extension. FMRI analysis found that,between unilateral, bilateral in-phase and anti-phase wrist flexion-extension,regions of brain activation were not mirror-symmetric but shared overlapping core motor regions (i.e. M1, S1). Task specific activation and deactivation we reestablished for bilateral in-phase and anti-phase wrist flexion-extension. Bilateral in phase wrist flexion-extension involved greater neural activity in a number of brain regions compared to bilateral anti-phase.

Finally, a cross-sectional cohort study was undertaken to compare the effects of unilateral and bilateral task modes on patterns of UL intralimb kinematics, interlimb coordination and brain activation in acute stroke individuals (chapter 5). Paretic arm movement was significantly smoother during a bilateral in-phase ARAT grasp task compared to unilateral and bilateral anti-phase task modes. Conversely, nonparetic arm movement was significantly slower and jerkier during both bilateral in phase and bilateral anti-phase compared to unilateral task modes. Coordination stability (although not significant) was higher and phase error was smaller during bilateral in-phase than bilateral anti-phase wrist flexion-extension. Patterns of brain activation varied considerably across all acute stroke participants. FMRI analysis found that the regions of brain activation were not mirror-symmetric between unilateral, bilateral in-phase and anti-phase wrist flexion-extension. Task specific activation and deactivation were established for bilateral in-phase and anti-phase wrist flexion-extension. Bilateral in-phase wrist flexion-extension involved greater neural activity in a number of brain regions compared to bilateral anti-phase.

Overall, the thesis demonstrated differential motor and neural responses between unilateral and bilateral task modes and between the healthy and the stroke population. Importantly, the thesis found evidence of a potential treatment effect of in-phase BT in improving paretic movement smoothness. The finding that bilateralin-phase movement activated fewer brain regions than unilateral movements combined pointed to the presence of an interlimb coupling effect that could potentially facilitate paretic motor performance. Brain regions identified in this thesis can be used as regions of interest (ROI) in future connectivity analyses to map out the directional interaction within neural networks specific to BT.
Date of Award2016
Original languageEnglish
Awarding Institution
  • Glasgow Caledonian University
SupervisorFrederike van Wijck (Supervisor), Helen Gallagher (Supervisor) & Jacqui Morris (Supervisor)

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