Date of Award
Ph.D. in Psychology
Kenneth J. Sufka
John M. Rimoldi
John N. Young
Cognitive bias is a phenomenon that presents in individuals suffering from anxiety and depression where anxious individuals tend to adopt a more pessimistic interpretation of ambiguous aversive stimuli and depressed individuals tend to adopt both a more pessimistic interpretation of ambiguous aversive stimuli as well as a less optimistic interpretation of ambiguous appetitive stimuli. Such biases have been pharmacologically reversed using anxiolytics and antidepressants. The chick anxiety-depression model has observed more pessimistic-like and less optimistic-like behavior in approach/avoidant runway performance to ambiguous aversive and ambiguous appetitive stimuli, respectively. Further, both types of cognitive biases have been reversed in a White Leghorn strain using the antidepressant imipramine. One goal of the current study was to examine whether cognitive biases of more pessimism and less optimism would manifest in a pattern reflecting the stress vulnerability and resiliency in Black Australorp and Production Red strains, respectively. Non-isolated and isolated (90 min) chicks were tested in a straight alley maze under an ambiguous appetitive (75c:25o) and an ambiguous aversive (25c:75o) stimulus cue with start and goal latency and distance traveled as the dependent measures. Less optimistic-like behavior and more pessimistic-like behaviors were observed under the 75c:25o and 25c:75o stimulus cues, respectively. Interestingly, stress vulnerability on cognitive bias in BAs presented primarily in non-isolated conditions. A second goal of the current study was to examine if cognitive biases in BAs could be reversed in a manner that parallels the strain's differential drug responsivity, whereby ketamine would reverse and imipramine would fail to reverse cognitive bias. Non-isolated and isolated (90 min) chicks received an administration of either a physiological saline vehicle, 10.0 mg/kg of imipramine and 10.0 mg/kg of ketamine prior to maze testing which followed the same procedure as Experiment 1. Imipramine and ketamine failed to produce a significant antidepressant effect on DVoc rates in isolated chicks. Consistent with the inability to detect a significant ketamine effect, more pessimistic-like behavior was not reversed under the 25c:75o stimulus cue. Surprisingly, not only did the 75c:25o stimulus cue fail to show less optimistic-like behavior, but the observed effects were in the opposite direction. The absence of a ketamine effect may be due to experimental procedures necessary to quantify cognitive bias. Collectively, the current study identified cognitive biases of more pessimism and less optimism in a stress-vulnerable Black Australorp and a stress-resilient Production Red strain. Surprisingly, the most robust strain difference presented between non-isolated conditions. These findings strengthen homologies between clinical populations by providing validative support to the identification of a stress-vulnerable and stress-resilient strain which further validate the chick anxiety-depression model as a neuropsychiatric simulation.
Hymel, Kristen Anne, "The Effects of Ketamine on Cognitive Bias in a Stress Vulnerable Chick Strain" (2013). Electronic Theses and Dissertations. 1525.
Emphasis: Experimental Psychology