The performance of cognitive behaviors requires
an activated, aroused cerebral cortex. Although studies
have shown that there are decrements of cognitive functions
in the elderly, changes in arousal with aging have not
been fully studied. Our objective was to learn if there
are attention–arousal changes associated with aging.
Visual stimuli were presented to induce orienting responses
or arousal reactions. Because changes in pupil size reflect
changes in arousal, we recorded and compared pupillary
responses of young and older normal participants using
infared pupillography. During the 1 s that we recorded
pupillary changes, we found major phases: a brief initial
constriction (C1), then a maximal dilation (D1)—an
arousal response, followed by 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 response is not dramatically altered with aging,
habituation appears to be delayed. (JINS, 2000,
6, 348–350.)