An fMRI Study of Command Following and Communication Using Overt and Covert Motor Responses: Implications for Disorders of Consciousness

Abstract

We used functional magnetic resonance imaging (fMRI) to explore neural mechanisms of command following or communicating using executed or imagined movements, in order to understand why most covertly aware patients cannot communicate. 15 healthy participants executed or imagined arm movements that were either selected by them or pre-determined. We also explored non-volitional motor activity by passively moving participants. Response selection involved greater activity in high-level associative areas in frontal and parietal regions than following commands. Furthermore, there was no interaction between response and modality. Neural activity during passive movement exceeded that of active (volitional) movement in sensorimotor regions. Our results suggest that the ability to select between motor responses is not dependent on how that response is expressed (via motor execution/imagery). They also suggest a potential neural basis of the distinction in cognitive abilities seen in DOCs. Finally, passive movement could be applied to study unresponsive patients’ motor systems