Ontogeny of eyeblink conditioned response timing in rats.
Eyeblink conditioned response (CR) timing was assessed in adult and infant rats. In Experiment 1, adult rats were trained with a 150-ms tone conditioned stimulus (CS) paired with a periorbital shock unconditioned stimulus (US; presented at 200- or 500-ms interstimulus intervals [ISIs]). The rats acquired CRs with 2 distinct peaks that occurred just before the US onset times. Experiments 2 and 3 examined developmental changes in CR timing in pups trained on Postnatal Days 24-26 or 32-34. Experiment 3 used a delay conditioning procedure in which the tone CS continued throughout the ISIs. Pups of both ages exhibited robust conditioning. However, there were age-related increases in the percentage of double-peaked CRs and in CR timing precision. Ontogenetic changes in eyeblink CR timing may be related to developmental changes in cerebellar cortical or hippocampal function.
Freeman
John H
JH
Department of Psychology, University of Iowa, Iowa City 52242, USA. john-freeman@uiowa.edu
Nicholson
Daniel A
DA
Muckler
Adam S
AS
Rabinak
Christine A
CA
DiPietro
Norma T
NT
D000375:Aging / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D001522:Behavior, Animal / Q000502:physiology; D003214:Conditioning, Classical / Q000502:physiology; D003215:Conditioning, Eyelid / Q000502:physiology*; D005108:Extinction, Psychological; D007858:Learning; D008297:Male; D008570:Memory, Short-Term; D009799:Ocular Physiological Phenomena; D051381:Rats; D020318:Rats, Long-Evans; D011930:Reaction Time / Q000502:physiology