Rewiring the Brain After Stroke: A Novel Neuromodulatory Intervention to Improve Neuromuscular Control

A stroke can have devastating consequences for an individual’s gait and mobility, and difficulties often continue well after discharge from rehabilitation. Increased knowledge about the role of neural plasticity in stroke recovery has led to the development of neuromodulatory interventions. Neuromodulatory interventions can increase neural activity in the ipsilesional primary motor cortex and have potential to be used as rehabilitation adjuncts to facilitate recovery following stroke. This thesis explores a novel neuromodulatory intervention, thought to have neurophysiological underpinnings similar to that of paired associative stimulation (PAS), and is here called novel paired associative stimulation (novel PAS). Novel-PAS pairs the movement-related cortical potential (MRCP), recorded during imagined or voluntary movement, with peripheral electrical stimulation over a nerve supplying the target muscle. Novel-PAS can increase corticomotor excitability in the target muscle in healthy people. In people with stroke, a single study has shown increased corticomotor excitability for up to 30 minutes post-intervention, and improvements in lower limb impairment and function after three sessions targeting the ankle dorsiflexor muscles. Previous research has not considered how novel-PAS could best be implemented in rehabilitation, or assessed its feasibility when applied over several weeks. The aim of this thesis was to address gaps in the novel-PAS knowledge base. Specifically, this research investigates: the efficacy of novel-PAS beyond 30-minutes post intervention, the immediate effects of novel-PAS in people with stroke, and the feasibility of delivering a four week intervention. Study A, a within-subject, repeated-measures experiment in healthy people, explored the immediate effects of novel-PAS, and demonstrated increased corticomotor excitability to the tibialis anterior muscle for 60 minutes post-intervention. The findings provide new understanding about the duration of neuromodulatory effects following novel-PAS, ...