Movement-related Cortical Activation: Simultaneous Monitoring of Near-infrared Spectroscopy Signals and Movement-related Cortical Potentials

This study was designed to evaluate hemodynamic and electrophysiological responses in the motor cortex to voluntary finger pinching movements in healthy humans. Near-infrared spectroscopy (NIRS) signals and movement-related cortical potentials (MRCP) were recorded simultaneously. Three healthy right-handed subjects performed 100 trials of voluntary right thumb- index finger pinching with approximate 10 s intervals at their own pace. Throughout the session, 48 regions of the bilateral motor cortex were assessed by NIRS, while MRCPs were simultaneously monitored at Fz, Cz, C3, and C4 of the 10-20 International System. An electromyogram (EMG) was also recorded from the right first dorsal interosseus muscle. MRCPs, which were clearly detected in all subjects, started 1585±13 ms before EMG onset and peaked 110±13 ms after EMG onset. NIRS data showed bilateral prefrontal cortical (PFC) and bilateral dorsal premotor cortical (dPMC) activation during the preparation phase (PFC: peaking at 0.5±0.1 s before EMG onset, dPMC: peaking at 0.5±0.1 s before EMG onset). Following the cortical activation, the hand area of the sensorimotor cortex, which was dominantly activated on the left, peaked at 3.7 ± 0.2 s after EMG onset. These results indicate that our technique allowed detailed study of the motor control system