Neuroplasticity and Brain Imaging Research: Implications for Rehabilitation

INVESTIGATION OF NEUROPLASTICITY during the past decade has extended translational projects to rehabilitation research and led to development of new clinical interventions. Advances in noninvasive neuroimaging techniques, including functional magnetic resonance imaging, transcranial magnetic stimulation (TMS), magnetic source imaging, and optical imaging have facilitated investigation of mechanisms mediating recovery and rehabilitation of neurologic disease and injury.

Neuroplasticity research has provided insights such as shifts over time in the relative contributions of brain regions ipsilateral and contralateral to the site of a unilateral hemispheric lesion in stroke. In contrast to the previously held concept that reorganization of function in homologous regions of the intact hemisphere facilitates recovery from stroke, we now appreciate that good functional outcome is associated with increasing participation of regions in the damaged hemisphere, including sites adjacent to the infarct. Use-dependent neuroplasticity has also gained wide acceptance in animal models, brain imaging of patients, and studies of innovative therapies such as constraint-induced movement therapy that have a foundation in laboratory research. As presented in this supplement, investigators are using neuroimaging techniques to evaluate the effects of interventions on adaptive reorganization of function. This approach has enabled investigators to compare the effects of alternative approaches to motor rehabilitation on neuroplasticity, and similar applications to training language and visual attention are in progress. Moreover, TMS and transcranial direct current stimulation have emerged as potential therapies delivered either in combination with behavioral training or in isolation, which could enhance use-dependent neuroplasticity and inhibit suboptimal reliance on the intact hemisphere. Functional electric stimulation also appears to facilitate use-dependent neuroplasticity in stroke patients with motor deficit. Relevant to the intervention studies described in the supplement is the change in cortical representation associated with practice and learning new skills in healthy subjects. Recent studies suggest that practice effects could potentially benefit cognitive function more generally and stimulate cortical remodeling.

Contributors to this supplement also show how functional brain imaging has altered current concepts of the mental activity in patients who are minimally conscious. More sensitive monitoring of changes in brain activity could lead to more accurate prognostication for recovery from devastating neurologic injury and facilitate planning for rehabilitation.