The characteristics of cortical activation during hand laterality task after ischemic stroke

Abstract

Motor imagery (MI) has shown its effects as a neuro-rehabilitation strategy. But limited literature emphasized the neural mechanisms during MI in stroke patients. The purpose of this study is to investigate the features of cortical activation during the hand laterality task (HLT) using electroencephalogram (EEG) in stroke patients. Nine ischemic stroke patients and five age-matched control were recruited. EEG and behavior performances of subjects were recorded in the left/right hand judgement (HLT), which involves visual processing and mental rotation, and provides a good paradigm to study motor imagery and visual perception of hands. Reaction time (RT) and accuracy were used to evaluate the behavior performances; moreover, event-related potential (ERP) with the frequency from 0.5 to 40 Hz was analyzed to investigate the cortical activation. EEG and T1-weihted structural MRI (TR = 7.42 ms, TE = 3.26 ms) were incorporated to reveal the source activity of the cortex during the task. The RT is significantly longer in patient group than control, while the accuracy has no statistical difference between two groups ( Fig. 1 ). The ERP analysis showed that P200 (in parietal zone) and P300 (in central zone) amplitudes were significantly lower in stroke patients ( Fig. 2 ). Besides, source analysis shows the inactivation of the frontal lobe during P200 and bias activation during P300 when patients underwent this task. The manifestations of EEG signals during HLT in stroke patients indicated the impairments of visual perception and mental rotation related cognitive processes. It suggested that the underlying neural mechanisms of MI in time course and helped to optimize rehabilitation strategy.