Autonomic responses to meaningful and non-meaningful auditory stimuli in coma.

In a group of poisoned patients, the lowest MCS (Munich Coma Scale) vigilance grade at which patients responded when called by their names was determined. In 12 patients at this vigilance grade, the extent to which the meaning of the names contributed to their reactions was investigated. Their first name and a control stimulus (name backwards) were repeatedly presented via headphones. Stimulus intensity was 90 dB(A). During stimulus presentation, changes in heart rate, finger pulse amplitude, and electrodermal activity were recorded. A comparison between responses under both stimulus conditions revealed that the first reactions of poisoned patients to their names are primarily elicited by the physical properties of the stimulus.