Developmental changes in point-light walker processing during childhood and adolescence: an event-related potential study.

To investigate developmental changes in the neural responses to a biological motion stimulus, we measured event-related potentials (ERPs) in 50 children aged from 7 to 14 years, and 10 adults. Two kinds of visual stimuli were presented: a point-light walker (PLW) stimulus and a scrambled point-light walker (sPLW) stimulus as a control. The sPLW stimulus had the same number of point-lights and the same velocity vector of point-lights as the PLW stimulus, but the initial starting positions were randomized. Consistent with previous ERP studies, one positive peak (P1) and two negative peaks (N1 and N2) were observed at around 130, 200 and 330 ms, respectively, in bilateral occipitotemporal regions, in all age groups. The latency of the P1 component was significantly shorter for the PLW than sPLW stimulus in all age groups, whereas the amplitude was significantly larger for the PLW than sPLW stimulus only for the 7-year-old group. The P1 amplitude and N1 latency were linearly decreased with age. The negative amplitudes of both N1 and N2 components of the PLW stimulus were significantly larger than those of the sPLW stimulus in all age groups. P1-N1 amplitude was changed by development, but not N2 amplitude. These results suggest that the intensity (P1) and timing (N1) of early visual processing for the PLW stimulus changed linearly throughout childhood and P1-N1 amplitude at occipitotemporal electrodes and N1 latency in 10-year-olds, but not 11-year-olds, was significantly larger than that in adults. For the amplitudes of the N2 component in response to PLW and sPLW stimuli in 7-8-year-old subjects were not statistically different from those in adults at occipitotemporal electrodes. These results suggest that the neural response to the PLW stimulus has developed by 10 years of age at the occipitotemporal electrode.