Graduate Student Seminar Series – Sima Buchnak
Graduate Student Seminar Series
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Location: MS2158 – 1 King’s College Circle
Presentation Title: Functional and Structural Connectivity in Paediatric Post-Stroke Dystonia
Abstract:
Introduction: Dystonia is a motor impairment that affects 20% of children post basal ganglia arterial ischemic stroke (CAIS). Disrupted inhibitory processing in the sensorimotor cortex is implicated and reflected by alterations in beta event-related desynchronization (ERD). In a prior magnetoencephalography (MEG) study during a cognitive-motor task, beta ERD response amplitude was larger in both hemispheres of CAIS with no dystonia (D-), and the non-lesioned hemisphere of CAIS with dystonia (D+), compared to healthy controls (HC). This finding was suggestive of compensatory sensorimotor plasticity.
Objective: To determine whether beta ERD shows similar trends during a passive movement task and explore associations with corticospinal tract (CST) microstructure.
Methods: Diffusion magnetic resonance imaging (MRI) and MEG data were collected in CAIS (D+/D-) and HC participants from a prior study. A passive movement task assessed beta reactivity without the confounding effects of impaired motor execution. CST microstructure was evaluated using tractography and diffusion metrics.
Results: Twenty-six participants (16CAIS: 8D+/8D- ;10HC) were included (Table 1). Compared to HC, beta ERD amplitude during passive movement was greater in the lesioned hemisphere of D+ (p = 0.036) and the non-lesioned hemisphere of D- (p = 0.030) patients, with similar trends in the other hands (Fig 1). In the lesioned hemisphere, mean diffusivity (MD) was highest in D+, intermediate in the D-, and lowest in the HC group. Fractional anisotropy (FA) showed an inverse trend. Non-lesioned hemispheres showed comparable MD and FA across groups (Fig 2).
Conclusion: Group differences in CST.microstructure were consistent with motor outcomes but did not mirror the functional measures of inhibitory processing. Our finding of higher beta ERD during passive movement of both hands, in all CAIS groups (D+/D-) compared to controls, was unexpected.
These studies suggest that the basic function of the CST is relatively preserved in dystonia. Future studies should investigate the potential role of cognition in the maladaptive response of dystonia.
Hsu P., et al., (2025) Hum Brain Mapp. 46 e7020
Supervisor Name: Douglas Cheyne
Year of Study: 2
Program of Study: MASc
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