title: Short intertrial intervals impair water maze performance in old Fischer 344 rats.
abstract: 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.
authors.affiliation: Life Sciences Division, University of Toronto, Scarborough, Ontario.
authors.forename: J T
authors.initials: JT
authors.lastname: Rick
authors.forename: M P
authors.initials: MP
authors.lastname: Murphy
authors.forename: G O
authors.initials: GO
authors.lastname: Ivy
authors.forename: N W
authors.initials: NW
authors.lastname: Milgram
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D004198:Disease Susceptibility; D004924:Escape Reaction / Q000502:physiology; D005221:Fatigue / Q000503:physiopathology; D005260:Female; D008297:Male; D018782:Maze Learning / Q000502:physiology*; D008996:Monoamine Oxidase Inhibitors / Q000494:pharmacology; D011597:Psychomotor Performance / Q000502:physiology*; D051381:Rats; D011916:Rats, Inbred F344; D011930:Reaction Time; D012642:Selegiline / Q000494:pharmacology; D013312:Stress, Physiological / Q000503:physiopathology; D013550:Swimming / Q000502:physiology; D013696:Temperature; D013997:Time Factors; D014867:Water
chemical_list: D008996:Monoamine Oxidase Inhibitors; D014867:Water; D012642:Selegiline