Subordination in female rats impedes learning as determined by a judgment bias training protocol

• Published in: Journal of veterinary behavior 2020-07, Vol.38, p.56-60
• Main Authors: Barker, Timothy Hugh, Howarth, Gordon Stanley, Whittaker, Alexandra Louise
• Format: Article
• Language: English
• Subjects: animal learning; cognitive bias; imposed subordination; judgment bias test; psychosocial stress
• ISSN: 1558-7878
• DOI: 10.1016/j.jveb.2020.05.009

Legislative direction has encouraged the standard laboratory practice of group-housing rats used for scientific purposes. It has been demonstrated that this type of housing causes the induction of anxiety-like behaviors in subordinate animals. Despite previous studies documenting the negative effects of stress on learning, there has been relatively little attention given to the effects of subordination on animal learning. The aim of this study, therefore, was to assess the effects of social stress leading to subordination on rat learning aptitude. Twenty, female, Sprague-Dawley rats were exposed to three training trials of a commonly used judgment bias test. The results showed that dominant animals took significantly fewer days (42.50 ± 5.15) to learn the training criteria than their subordinate-subdominant (68.60 ± 4.61) (P = 0.003) and subordinate cage-mates (64.60 ± 4.61) (P = 0.015). This implied that subordination, as imposed by standard group-housing, could impede the ability of subordinate animals to learn. In conclusion, at least in group-housed female rats, researchers should modify experimental design to account for social status when learning parameters are a critical study outcome.