Altered lateralized readiness potential in stroke patients during healthy and paretic hand movements

After stroke, one of the most critical problems for recovering patients is motor dysfunction in the limb contralateral to the affected hemisphere. Several mechanisms may contribute to the recovery of motor function after stroke. One is the recovery of neural pathways within the affected hemisphere. The contribution of the ipsilateral hemisphere is also widely discussed as it may be entirely responsible for motor recovery. The lateralized readiness potential (LRP) is one of the markers of interhemispheric balance during motor preparation. It is a fast negative deflection approximately 200 ms before the motor response and reflects premovement activity in the primary motor cortex (M1) during movement preparation. However, the dynamics of the LRP in stroke patients remain relatively unexplored. Our study examines cortical potentials associated with motor trials in 20 post-stroke hemiplegic patients. During the experiment, participants were instructed to perform a finger extension task involving button pressing with both hands. In cases where the movement could not be performed, they were asked to imagine it while concentrating on the hand. Electroencephalographic and electromyographic activity was recorded throughout the study. We observed changes in LRP patterns in stroke patients (Figure 1) and were able to assess the contribution of the unaffected hemisphere to functional recovery of the paretic limb. Most patients with chronic stroke showed atypical lateralization of the LRP, which may indicate bilateral involvement of M1 in the ipsilateral hemisphere in the control of limb movements.