Dynamics of P300 component of acoustic evoked potential in postraumatic unconsciousness

: In order to reveal features of the brain reactions to external stimuli in the course of consciousness recovery after a severe craniocerebral injury, component P300 of acoustic evoked potential was analyzed in 9 patients with chronic and 32 patients with reversible unconsciousness. In patients with chronic unconsciousness, P300 parameters displayed a linear correlation with the current functional state. However, this component remained significantly different from its normal shape and varied only in a narrow range. In patients with reversible unconsciousness, time course of changes in amplitude and latency between recovery stages was of linear character with a tendency to normalization. The findings suggest that, in reversible unconsciousness states, processing of sensory information at different recovery stages may be performed with various functional systems that determine varying quality of processing, whereas changes in chronic unconsciousness are caused by a decrease in the number of active elements within the same functional system.