Mismatch negativity: an index of subclinical neurological differences in HIV patients during rapid perceptual processing

Thirteen asymptomatic HIV-infected (HIV+) and 13 healthy control (HIV-) subjects were instructed to detect "oddball" target tones from among a sequence of nontarget tones delivered rapidly (3 tones/second) in one ear while ignoring a similar sequence delivered simultaneously in the opposite ear. Event-related potentials (ERPs) to all stimuli were recorded from midline scalp sites. Both groups produced ERP correlates, termed the "mismatch negativity" (MMN), to the oddball tones during delivery. However, the HIV+ group produced MMNs that differed in morphology from those of the HIV-group, suggesting that HIV may alter attentional perceptual processing. These results suggest that auditory ERPs elicited by rapid, dichotic stimulus presentations may be useful in monitoring subclinical effects of HIV-related neuropathology on perceptual processing.