Olfactory sensitivity, learning and cognition in young adult and aged male Wistar rats

• Published in: Physiology & behavior Vol. 81; no. 3; pp. 435 - 442
• Main Authors: Kraemer, Simone, Apfelbach, Raimund
• Format: Journal Article
• Language: English
• Published: Cambridge Elsevier Inc 01-05-2004; New York, NY Elsevier
• Subjects: Acetates; Aging; Aging - psychology; Animal; Animals; Biological and medical sciences; Cognition - physiology; Conditioning; Discrimination Learning - physiology; Fundamental and applied biological sciences. Psychology; Learning - physiology; Learning. Memory; Male; Odor discrimination; Odor memory; Odorants; Olfactory sensitivity; Olfactory system and olfaction. Gustatory system and gustation; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Rat; Rats; Rats, Wistar; Sensory Thresholds; Smell - physiology; Vertebrates: nervous system and sense organs; Odor discrimination; Aging; Rat; Olfactory sensitivity; Odor memory; Senescence; Perception threshold; Rodentia; Cognitive ability; Instrumental conditioning; Psychophysics; Experimental study; Discrimination task; Learning; Vertebrata; Mammalia; Acquisition process; Animal; Developmental stage; Age; Comparative study; Chemical stimulus
• ISSN: 0031-9384; 1873-507X
• DOI: 10.1016/j.physbeh.2004.01.012

Psychophysical experiments with male Wistar rats, ranging from 2 to more than 25 months old, revealed age-related differences in olfactory sensitivity. The highest sensitivities were found in rats 13 months old, and the lowest sensitivity was found in the group aged 25 months and older. Consequently, we considered the hypotheses that young rats will require less time and less trials than aged conspecifics to learn an olfactory discrimination task and that olfactory cognitive abilities will be reduced in older individuals. Rats were initially trained in an olfactometer using operant techniques to discriminate between the odor ethyl acetate (EA) and clean air. Next, young adult and 28-month-old rats were tested on seven different go/no-go odor discrimination tasks. Aged rats performed as well as young adults did on all tasks and we conclude that, for a variety of odor discrimination problems, aged rats show no deterioration in learning ability.
This is the first report on olfactory sensitivity, learning ability and cognition in Wistar rats that have passed the normal life span for this strain. Data show that the inability to learn and cognitive deficits do not necessarily develop with age.