Selective amygdala lesions facilitate acquisition of signaled leverpress avoidance in Wistar Kyoto and Sprague Dawley rats.
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The Wistar Kyoto rat strain (WKY) shows stress vulnerability via both autonomic (e.g., heart rate, gastric ulcers, etc.) and behavioral (freezing, inactivity) reactivity in stress inducing situations. The WKY rat has performed exceptionally well in passive avoidance tasks (Pare, Physiol. Behav. 54:845, 1993), where exaggerated fear responses and behavioral inactivity are the most efficient responses to make. Recently Servatius et al. tested WKY rats on an active avoidance task, using a tone to signal a lever press to avoid footshock (Servatius et al., Behav. Brain Res., 2008). It was hypothesized that increased autonomic responses and behavioral inactivity would hinder the learning of the active lever press response. The opposite was found. In addition, the WKY rats showed significant resistance to extinguishing the lever press response when the foot shock was no longer being delivered. We have begun to study the role of the amygdala in the increased acquisition of active avoidance learning in WKY rats. In the present study, selective lesions of the central and basolateral amygdala were used to examine the role of the amygdala in avoidance learning in WKY rats compared to Sprague Dawley (SD) controls.