Dynamics of a Stimulation-evoked ECoG Potential During Stroke Rehabilitation - A Case Study

Abstract

Cortical stimulation is being investigated as a possible tool to support stroke rehabilitation. In particular the analysis of stimulation-evoked neural activity during the rehabilitation process might be helpful to gain a better understanding of the brain reorganization associated with functional recovery after stroke. In this paper, the stimulation-evoked brain activity from a patient with implanted epidural electrodes undergoing an intervention using of brain-computer interfaces combined with cortical stimulation for stroke rehabilitation has been analyzed. We identified a component of the evoked cortical activity that exhibited several characteristics that have not been described before: A significant latency decrease over the course of the rehabilitation training, a significantly smaller latency if the patient attempted to move his paralyzed hand compared to rest and a significant correlation of the latency with the spectral power of the ECoG signal. In addition to the latency, other parameters such as the peak amplitude of the evoked activity were tested as well, but showed a smaller effect size. We hypothesize that such “dynamic” components of the evoked activity that appear to be correlated with the rehabilitation process and the ongoing brain signal could be a target for future closed-loop stimulation systems.