Recovery of motor function after stroke

Abstract

The human brain possesses a remarkable ability to adapt in response to changing anatomical (e.g., aging) or environmental modifications. This form of neuroplasticity is important at all stages of life but is critical in neurological disorders such as amblyopia and stroke. This review focuses upon our new understanding of possible mechanisms underlying functional deficits evidenced after adult-onset stroke. We review the functional interactions between different brain regions that may contribute to motor disability after stroke and, based on this information, possible interventional approaches to motor stroke disability. New information now points to the involvement of non-primary motor areas and their interaction with the primary motor cortex as areas of interest. The emergence of this new information is likely to impact new efforts to develop more effective neurorehabilitative interventions using transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) that may be relevant to other neurological disorders such as amblyopia.

FIGURE 1

Movement has been divided into three broad cortical networks that reflect each stage of movement. It is likely that stroke has a differential effect on each of the networks and by understanding the interaction between and within these networks we can devise novel methods to improve motor function after stroke. The affected hemisphere is shaded in gray while the non-affected hemisphere is white. (A) Motor processes that precede movement such as motor planning. For example, this network can be accessed using motor imagery and action observation. (B) Discharge via the corticospinal tract to produce movement. Although all of these networks are present during physical movement this cortical network is dominant when combined with the other 2. (C) Sensory feedback or input. For example, this can be accessed using peripheral nerve stimulation.