Age and functions of the transient component of ON and OFF responses in visual processes

Detections of appearances and disappearances in briefly interrupted complex patterns were examined in young and old subjects. According to neurophysiological evidence developed by Singer and Phillips (1974), the detection rates for the two types of events, which differ substantially as pattern durations and interstimulus intervals vary, are attributable to inhibitory interactions of ON- and OFF-centre relay cells of the lateral geniculate nucleus. The interactions affect the latency and amplitude of the transient component of the cells' responses. Phillips and Singer (1974) found that the neural model predicted the ability to detect the events. Using the same paradigm, we replicated their findings and found that differences in patterns of detection rates for appearances and disappearances in young and old subjects were consistent with the hypothesis that inhibitory interactions are stronger in older subjects, producing longer latency of OFF-centre relay cells. The neural model and the hypothesized age-related increase in inhibitory interactions are consistent with findings