A time contraction effect of acute tail-pinch stress on the associative learning of rats.
The effect of tail-pinch stress interpolated between the saccharin conditioned stimulus (CS) and the illness-inducing unconditioned stimulus (US) during long-trace taste-aversion conditioning was examined in young- and old adult rats with a two-cylinder (saccharin versus water) test. A 2 x 2 x 4 factorial ANOVA was performed on percent-preference-for-saccharin data, with age (young, old), stress condition (stressed, non-stressed), and CS-US interval (22.5-, 45-, 90-, and 180-min) being the factors under consideration. The ANOVA yielded only significant main effects of stress condition and CS-US interval. These findings indicate that stress weakens the CS-US association as evidenced by a higher percent preference for saccharin in the stressed rats than in non-stressed rats at all CS-US intervals. A comparison of the stressed and non-stressed conditioned rats with pseudo-conditioned controls showed that the non-stressed rats formed strong aversions up to the 45-min CS-US interval whereas the stressed rats showed no conditioning beyond the 22.5 min CS-US interval, indicating that stress decreases the effective CS-US interval. Results were interpreted in terms of time-contraction and an internal biological countdown timer hypothesized to govern processes involved in associative learning over long delays.
Misanin
James R
JR
Susquehanna University, Selinsgrove, PA, USA.
Kaufhold
Sarah E
SE
Paul
Rebecca L
RL
Hinderliter
Charles F
CF
Anderson
Matthew J
MJ
D000818:Animals; D001245:Association Learning / Q000502:physiology*; D001522:Behavior, Animal / Q000502:physiology; D003214:Conditioning, Classical / Q000502:physiology; D008297:Male; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D012439:Saccharin / Q000008:administration & dosage; D013315:Stress, Psychological / Q000523:psychology*; D013623:Tail / Q000502:physiology*; D013997:Time Factors
D012439:Saccharin