Fig. 6.

Following 3 weeks of the sedentary, FW or VW conditions, rats underwent sham surgery or received bilateral injects of ibotenic acid into the medial prefrontal cortex (Lesion). Three weeks later, rats were exposed to 100 uncontrollable tail shocks (Stress) or remained in their home cages (No Stress). Shock-elicited freezing and shuttle box escape behavior were measured sequentially 24 h later. (A) Average time spent freezing during the 20-min observation period following administration of two fixed ratio-1 foot shock trials. (B) Average FR-2 escape latency across all 25 FR-2 escape trials. Stressor exposure produced exaggerated shock-elicited fear and interfered with shuttle box escape in sedentary rats regardless of lesion. These behavioral consequences of uncontrollable stress were prevented by both FW and VW regardless of whether the medial prefrontal cortex was lesioned 3 weeks prior to stress. Bars represent means ± SEM. *P < 0.0001 relative to all groups except each other.