Conditioned-Reflex Facilitation in Young and Older Adults

Abstract

Young ( 18 - 30 years ) and elderly ( 63 - 88 years ) human subjects received 70 trials of single - cue classical eyeblink conditioning ( paired group ), or 70 explicitly unpaired presentations of the tone conditioned stimulus ( CS ) and airpuff unconditioned stimulus ( unpaired group ). Before and after conditioning , reflex - eliciting white noise and corneal airpuff stimuli were presented alone or paired with the CS to investigate the effects of conditioning on eyeblink reflex amplitude . The results showed increased conditioned responses in the paired group compared to the unpaired group for the young but not the elderly subjects . There was , however , evidence of conditioned facilitation of noise - elicited reflexes in both young and elderly subjects . These data indicate that conditioned facili tation ofthe startle reflex may be a sensitive indicator ofclassical condi tioning processes in human subjects .