Estradiol modulation of the speed of an internal clock.

Abstract

Estradiol significantly influences dopamine (DA) activity in the striatum (e.g., J. B. Becker, 1990b), and researchers have strongly implicated striatal DA in the regulation of temporal integration in the seconds-to-minutes range (e.g., W. H. Meck, 1996). In the current experiment, the author examines the effect of acute estradiol administered prior to testing on a peak-interval (PI) timing task. The administration of 5 mug of estradiol 30 min prior to testing resulted in an immediate and proportional leftward shift in the timing functions relative to the PI functions obtained following the administration of the oil vehicle. The precision of the response functions was increased in a manner commensurate with the scalar property of interval timing without significant alteration of peak response rates. When timing behavior was assessed 3 days following estradiol or oil administration, no differences were found in the peak time of responding or in the precision of responding between estradiol- and oil-treated rats, indicating that the effects of estradiol on these measures of interval timing are short lived. Together, these findings indicate that estradiol selectively increases the speed of an internal clock, perhaps through facilitating striatal DA activity.