Characterizing cortical-cerebellar neurophysiology during visuomotor adaptation in chronic middle cerebral artery stroke

The acquisition of complex motor skills shapes our behavior and ability to adapt in everyday life. The underlying biological processes are complex, involving multiple neuroanatomic pathways and efficient communication within functional brain networks. Understanding the neural underpinnings of motor learning and adaptation within the context of health and disease is fundamental, and particularly relevant to brain injury, recovery, and rehabilitation. Following middle cerebral artery (MCA) stroke, individuals often experience upper limb motor impairment that continues into the chronic phase. Motor recovery is influenced by the reorganization of brain networks compensating for tissue damage and by well-designed motor rehabilitation programs that promote use of the remaining motor output. However, predicting the outcome of rehabilitation has been difficult and recovery is often incomplete. Impairments in cortical-cerebellar pathways may underlie motor deficits and influence motor function, yet, to date, little work has examined the influence of cortical-cerebellar relationships in relation to motor adaptation in chronic MCA stroke. The overall objective of the present thesis was to investigate the impact of MCA stroke on cortical-cerebellar neurophysiology and motor adaptation using transcranial magnetic stimulation (TMS). TMS was employed to investigate cortical-cerebellar excitability at baseline, and then during a sensorimotor adaptation task in a group of chronic MCA stroke and a group healthy older controls. Both groups had similar cortical-cerebellar excitability before and during the adaptation task. However, individuals with MCA stroke are impaired compared to healthy age matched controls in sensorimotor adaptation. This suggests that adaptation deficits after MCA stroke may be influenced by motor network substrates beyond the cerebellum. The present thesis contributes new knowledge towards understanding the impact of chronic MCA stroke on cortical-cerebellar pathways and sensorimotor adaptation. The finding of sufficient cortical-cerebellar connectivity suggests that it may be a candidate pathway for TMS stimulation to modulate motor related networks for stroke rehabilitation.Medicine, Faculty ofGraduat