Age-related Changes in Associative Learning for Olfactory and Visual Stimuli in Rodents

摘要

Memory for olfactory stimuli may be particularly affected by age-related brain changesin humans and may be an early indicator of cognitive impairment and Alzheimer'sdisease. Studies involving rats have offered insights into impaired cognition in agedanimals, but few have examined odor memory. Therefore, it is unclear whether aged ratsare a good model for possible age-related changes in odor memory in humans. Young(6-month-old) and old (24-month-old) rats were tested on associative learning tasksinvolving visual and olfactory stimuli. The first task examined age-related differencesin discriniination and reversal learning for olfactory and visual stimuli; the secondtask utilized an associative contextual learning task involving olfactory and visual cues.Although old rats were able to perform the olfactory and visual discrimination tasksas well as young rats, old rats displayed significant age-related impairment on thereversal learning and contextual learning tasks. The results suggest that aging mayhave a similar deleterious effect on odor memory in rats and in humans. The findingsmay have important implications for the selection of memory paradigms for futureresearch studies on aging. In addition, the use of an animal model to investigate theeffects of aging on odor memory will allow researchers the ability to investigate howage-related neuroanatomical and neurochemical changes may result in impaired odormemory.