Short forms of the "reference-" and "working-memory" Morris water maze for assessing age-related deficits.
Short forms of the reference- and working-memory versions of the Morris water maze, each limited to 10 trials, were examined for their reliability and sensitivity to age-related deficits in 16- and 24-month F-344 rats, relative to 2- to 2.5-month young controls. The reference-memory task used long intertrial intervals of 23 h, but required learning only one target location, while the working-memory task used shorter intertrial intervals of 60 min but required learning many different target locations. The reference-memory task was very reliable, revealed large age-related deficits, and correctly identified almost all aged rats as impaired relative to young controls. The working-memory task was less reliable, revealed smaller deficits than the reference memory task at 24 months, and did not discriminate as well between 2.5- and 24-month rats. Furthermore, in the working-memory task 16- and 24-month rats had longer swim paths than 2- to 2.5-month rats on the first trial of each trial pair, which is suggestive of a deficit in processing spatial information and raises questions about the validity of this test as a specific test of working memory. Although the working-memory procedures may be preferable under certain conditions, perhaps as a measure specific to hippocampal dysfunction, the reference-memory task seems more sensitive to age-related deficits and more accurately identifies older rats as impaired. These results are consistent with previous reports that age-related deficits in acquiring spatial learning tasks are common and that the magnitude of the deficit increases as the length of the retention interval increases.
Lindner
M D
MD
Department of Neuropharmacology, Bristol-Myers Squibb Pharmaceutical Research Institute, Wallingford, Connecticut 06492.
Balch
A H
AH
VanderMaelen
C P
CP
D000375:Aging / Q000502:physiology* / Q000523:psychology; D000704:Analysis of Variance; D000818:Animals; D008297:Male; D008568:Memory / Q000502:physiology*; D009483:Neuropsychological Tests; D011597:Psychomotor Performance / Q000502:physiology; D051381:Rats; D011916:Rats, Inbred F344; D012680:Sensitivity and Specificity