Impaired trace and contextual fear conditioning in aged rats.
Trace and contextual fear conditioning were evaluated in adult (3-6 months), early middle-aged (8-12 months), late middle-aged (16-20 months), and aged (24-33 months) Sprague-Dawley rats. After trace conditioning, aged animals exhibited significantly less freezing to the tone conditioned stimulus and training context. Levels of trace-cue and context conditioning were negatively correlated with age (r = -0.56 and -0.59, respectively) and positively correlated with each other (r = +0.52). Aged rats showed robust conditioning in short- and long-delay fear paradigms, suggesting that the trace interval, rather than the use of a long interstimulus interval, is responsible for the aging-related deficits in trace fear conditioning. The authors suggest that these aging-related conditioning deficits furnish useful indices of functional changes within hippocampus or perirhinal cortex.
Moyer
James R
JR
Department of Psychology, Yale University, USA. jrmoyer@uwm.edu
Brown
Thomas H
TH
D000161:Acoustic Stimulation / Q000009:adverse effects; D000367:Age Factors; D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D003214:Conditioning, Classical / Q000502:physiology*; D003463:Cues; D004597:Electroshock / Q000009:adverse effects; D005239:Fear; D046352:Freezing Reaction, Cataleptic / Q000502:physiology; D007859:Learning Disabilities / Q000503:physiopathology*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000502:physiology; D012684:Sensory Thresholds / Q000502:physiology; D013997:Time Factors; D014828:Vocalization, Animal