Long latency components of the visually evoked potential in man: effects of aging.

Visual stimuli were used to elicit event related potential (ERPs) from frontal, central, and parietal midline scalp of ten right-handed male subjects in each of five groups (mean ages 28, 47, 63, 72, and 79 years). Stimuli consisted of 35 mm slides in three categories: 80% background; 10% target; and 10% colorful novel slides. Amplitude and latency of four ERP components, N1, P2, N2 and P3 were examined with three-way analysis of variance. Significant differences were found among age groups, stimulus categories and scalp locations. Although ERP component amplitudes were minimally affected by age, two waves, N2 and P3, showed reliable age-related changes in latency with latencies of both being prolonged in older subjects. Advancing age was associated with an acceleration of P3 slowing. Latency increased from 0.8 msec per year between ages 28 and 63 to 1.6 msec per year between ages 63 and 79. An effort was made to relate these results to a neurophysiological model involving the possible neural mechanisms of the P3 component.