ABSTRACT

The development of lead stimulus modification of startle is characterized by increasing inhibitory and decreasing facilitatory modification during the childhood years. Inhibitory lead stimulus modification of startle is particularly weak during a stage of neurophysiological development that involves increased reactivity to stimuli at both cortical and subcortical levels. This neurophysiological stage, occurring during the preschool years, coincides with the Piagetian stage of preoperational behavior. Lead stimulus modification of startle matures during a period of cortical remodeling and other structural brain changes in association with other neurophysiological changes suggestive of the maturation of both cortical and subcortical inhibitory processes. This neurophysiological stage, occurring during the grade-school years, coincides with the Piagetian stage of concrete operations.

In contrast to lead stimulus modification of startle, mature rates of habituation of startle are already achieved during the preschool years. P300 responses to startling stimuli in school-age children show mature lead stimulus modification and habituation, as does the startle response itself. Attentional and affective modification of startle is different in children than in adults, but the direction of differences is inconsistent and requires further study. Autonomic, myogenic, and electroencephalography activity accompanying startle habituation in children do not habituate; heart rate increases as startle habituates, suggesting a state of arousal accompanying startle habituation. These relationships have not been studied in adults.