APA Dictionary of Psychology

a condition in which a person who has experienced severe brain injury or deterioration retains a limited awareness of self and environment through residual cognitive functions. The individual is awake and occasionally able to communicate and do simple voluntary activities that demonstrate an engagement with surroundings. For example, they may produce intelligible verbalizations (e.g., saying yes or no), follow simple commands (e.g., blinking when asked), gesture, track moving targets, grasp objects, or otherwise purposely respond to stimuli. Given that diagnosis is based on observations by clinicians of subtle, functionally useful behaviors over an extended period of time, MCS is difficult to distinguish from a vegetative state (wakefulness without any awareness). Despite the similar clinical presentations of the two conditions, research using brain imaging and event-related potentials reveals them to be quite different neurologically. Formerly called minimally responsive state; quasi-vegetative state.