The applicability of motor learning to neurorehabilitation

Abstract

Rehabilitation is a form of directed training and is therefore predicated on the idea that patients respond to such training by learning. However, true recovery (restitution) with behavioural training is not synonymous with learning. Animal models suggest that there is a unique milieu of heightened plasticity post-stroke that is responsible for reduction in impairment both through spontaneous biological recovery and increased responsiveness to training. In the chronic phase of stroke, plasticity returns to normal levels with the goal mainly being task-specific compensation via normal motor learning mechanisms. In humans, there is a time-limited period of spontaneous recovery but it has yet to be shown whether patients after stroke have increased responsiveness to training over this same interval. Thus, new forms of behavioural intervention for patients may have distinct effects depending on whether they are initiated in the sensitive period after stroke (training interacting with repair) or in the chronic phase (compensation via motor learning). It is to be hoped that new pharmacological and non-invasive brain stimulation approaches will allow the post-stroke sensitive period to be augmented, extended, and re-opened. There may also be a subset of patients with chronic stroke that respond to much higher doses and intensities of motor training.