Arousal response with aging: Pupillographic study

The performance of cognitive behaviors requires an activated, aroused cereb ral cortex. Although studies have shown that there are decrements of cognit ive functions in the elderly, changes in arousal with aging have not been f ully studied, Our objective was to learn if there are attention-arousal cha nges associated with aging. Visual stimuli were presented to induce orienti ng responses or arousal reactions. Because changes in pupil size reflect ch anges in arousal, we recorded and compared pupillary responses of young and alder normal participants using infared pupillography. During the 1 s that we recorded pupillary changes, we found major phases: a brief initial cons triction (C1), then a maximal dilation (D1)-an arousal response, followed b y constriction (C2), a habituation response. Although amplitude of these 3 phases was not different between the 2 groups, the interval between the D1 and C2 response was prolonged in the older group. Although the arousal resp onse is not dramatically altered with aging, habituation appears to be dela yed.