Shining Light on the Human Brain: An Optical BCI for Communicating with Patients with Brain Injuries

Functional near-infrared spectroscopy (fNIRS) is an emerging optical technology that can be used to monitor brain function at the bedside. Recently, there has been a great interest in using fNIRS as a tool to assess command-driven brain activity in patients with severe brain injuries to infer residual awareness. In this study, time-resolved (TR) fNIRS, a variant of fNIRS with enhanced sensitivity to the brain, was used to assess brain function in patients with prolonged disorders of consciousness (DOC). A portable system was developed in-house, and patients were assessed in their homes or long-term care facilities across London and the Greater Toronto Area, Canada. Five DOC patients and one locked-in patient were recruited in this study, and motor imagery was used to elicit command-driven brain activity. TR-fNIRS data were analyzed using the general linear modelling (GLM) approach, as well as with basic machine learning. Three patients showed activity with GLM, four with machine learning, and two with both techniques. Interestingly, the two patients that showed activity by both approaches also had detectable motor imagery activity by functional magnetic resonance imaging. These promising preliminary results highlight the potential of TR fNIRS as a tool to probe consciousness and map brain activity at the bedside.