fNIRS-based analysis of temporal changes of brain activation during long-term conditioning with functional electrical stimulation

The number of patients who is suffering from paralysis due to aging, accidents, or brain injuries are increasing worldwide. Consequently, there is a compelling need for effective methods for the recovery of motor functions. One suggested effective rehabilitation method consists of stimulating brain activity to induce plasticity. Previous studies have reported that lost motor function and efficiency due to brain damage can be regained by repeatedly increasing and decreasing brain activation. Functional electrical stimulation (FES) has shown its effectiveness in the recovery of motor function. Brain activity usually decreases with the improvement of muscle control by FES. This study investigated the generality of brain responses during rehabilitation with FES in order to elucidate the recovery mechanism. We monitored the brain activity of ten healthy subjects with fNIRS over a ten-day period (one experiment per day) during which FES induced knee joint movements. The current results suggest that the observed increases and decreases of brain activity by FES are common in a healthy subject.