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Neuroscience Journal
Volume 2015 (2015), Article ID 697659, 12 pages
Research Article

Sex Differences and the Impact of Chronic Stress and Recovery on Instrumental Learning

1Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405, USA
2Program in Neuroscience, Indiana University, Bloomington, IN 47405, USA

Received 7 January 2015; Revised 23 March 2015; Accepted 25 March 2015

Academic Editor: Jose Cimadevilla

Copyright © 2015 Angela L. McDowell et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We have previously shown that 21-day chronic restraint stress impacts instrumental learning, but overall few studies have examined sex differences on the impact of stress on learning. We further examined sex differences in response to extended 42-day chronic stress on instrumental learning, as well as recovery from chronic stress. Rats were tested in aversive training tasks with or without prior appetitive experience, and daily body weight data was collected as an index of stress. Relative to control animals, reduced body weight was maintained from day 22 through day 42 across the stress period for males, but not for females. Stressed males had increased response speed and lower learning efficiency during appetitive acquisition and aversive learning. Males overall showed slower escape shaping times and more shock exposure. In contrast, stressed females showed slower appetitive response speeds and higher appetitive and aversive efficiency but overall reduced avoidance rates during acquisition and maintenance for transfer animals and during maintenance for aversive-only animals. These tasks reveal important nuances on the effect of stress on goal-directed behavior and further highlight sexually divergent effects on appetitive versus aversive motivation. Furthermore, these data underscore that systems are temporally impacted by chronic stress in a sexually divergent pattern.