Functional neuroimaging techniques for the detection of brain reorganization after Stroke

Abstract

The mechanism of motor functional recovery after stroke is still largely unknown. However, recent advances in functional neuroimaging techniques, such as functional MRI (fMRI) and near infrared spectroscopy (NIRS) have enabled us to study directly the brain activity of humans. We have performed fMRI and NIRS on stroke patients from the acute through chronic stages using a task of unilateral hand movement. We have also visualized the pyramidal tracts with MRI diffusion tensor tractography. Our results suggest that motor functional recovery after stroke occurs primarily through use of the existing functional system when brain damage to the motor system is partial, recruiting functionally related systems when necessary or the damage is severe. These restorative and reorganizing processes occur within the first few months after stroke, and this period seems critical to motor function recovery.