Trial measurement of movement-related cortical dynamics using electroencephalography and diffuse correlation spectroscopy

To better characterize movement-related neurophysiological change, the authors propose to measure not only neural activity through the electroencephalogram (EEG) but also cerebral blood flow (CBF) using a new technology, near-infrared diffuse correlation spectroscopy (DCS). A preliminary trial is described, in which EEG, DCS, and exerted force were simultaneously recorded during a cue-triggered hand grip task. Eight channels of EEG were acquired from frontal, central, and occipital regions, and DCS signals were collected from locations over frontal and motor cortex. Event-related desynchronization (ERD) was observed at the onset of hand movement and lasted until movement ceased. EEG from the motor area showed a significant ERD in the 8-13 Hz mu band (p<0.001). Mean CBF increased during the task by 6.8 % (p<0.001) in the motor location and by 4.5 % (p<0.001) in the frontal location, respectively. These preliminary observations suggest that a combination of electrical and optical measurements may provide a more complete characterization of brain dynamics related to movement. A broader study is required to explore the potential benefit of these combined measurements when used as command signals for brain-computer interfaces.