Event-related potential correlates of early processing in normal aging.

Auditory event-related potentials were recorded from normal elderly and young adult subjects during simple reaction time and discrimination conditions. In both response conditions, the stimuli were randomly presented, as in an auditory "oddball" paradigm. It was found that NA, an index of early information processing, was significantly delayed in the elderly. Although the latency of N1 was not significantly different between the groups, the latencies of N2 and P3 were significantly longer for the aged subjects. The amplitudes of N1, NA1, NA2 and N2 showed no group differences. The raw amplitude of P3 showed a group difference in topography: Pz was greater than Fz for the young group, but not for the aged. When the amplitudes of NA1, NA2, and P3 were scaled, however, the topography of these components showed no significant group differences. These findings suggest that the age-related slowing of later ERP components and behavior may be partially accounted for by delays in early attention dependent perceptual processes, as indexed by NA.