Increased distractibility in closed head injury as revealed by event-related potentials

The present study demonstrates that event-related potentials (ERPs) may be used to reveal increased distractibility as a physiologically measurable co ndition after chronic closed head injury (CHI). ERPs were recorded from 17 chronic CHI subjects and from 17 healthy age-matched controls. Auditory sti muli consisted of variants of vowel /(o) over bar/ (standards) occasionally replaced by an /(e) over bar/ vowel (deviant). Subjects were instructed to ignore auditory stimuli while watching a silent movie. In the constant-sta ndard condition, the vowel /(o) over bar/ served as the standard and vowel /(e) over bar/ as the deviant. In the roving-standard condition, four varia nts of the vowel /(o) over bar/ were randomly used as standards in the same stimulus block. None of the stimuli were prototypes in the subjects' mothe r tongues. Deviant stimuli elicited significant MMNs in both groups in both conditions, which were significantly smaller in the roving-standard than i n the constant-standard condition. CHI victims showed significantly larger P3a amplitudes than controls in both conditions, apparently reflecting thei r enhanced involuntary sifting of attention and thus their increased distra ctibility. NeuroReport 11:1463-1468 (C) 2000 Lippincott Williams & Wilkins.