Journals of Gerontology Series A: Biological Sciences and Medical Sciences, Vol 51, Issue 4 B253-B260, Copyright © 1996 by The Gerontological Society of America
Short intertrial intervals impair water maze performance in old Fischer 344 rats
JT Rick, MP Murphy, GO Ivy and NW Milgram
Life Sciences Division, University of Toronto, Scarborough, Ontario.
Male and female Fischer 344 rats (N = 55) aged approximately 18, 21, and 24
months were tested for spatial learning in the water maze with intertrial
intervals of 1-4 min (Massed) or 23-33 min (Spaced). Animals tested in the
Massed condition showed an age-related impairment on trials to criterion;
rats aged 24 months performed more poorly than younger subjects. Spaced
animals did not differ at any age nor did they differ from 18- or
21-month-old Massed subjects. The youngest rats in both groups were
comparable to animals aged 7-8 months tested under Massed conditions. Tests
on swim distance, swim speed, and escape latency produced similar results.
Our data suggest that acquisition deficits in 24-month-old rats tested with
long intertrial intervals are due at least in part to increased
susceptibility to fatigue and/or thermal stress. Caution should be used,
therefore, when interpreting age-related impairments in water maze
performance.
