dorsomedial hypothalamus, the latter a structure linked to integration of endocrine, autonomic and behavioral stress responses. However, exposure to CVS caused FosB activation in regions not affected by repeated restraint, including the posterior hypothalamus and the NTS, both of which project to the PVN. Moreover, CVS-induced FosB expression in the medial PFC was increased significantly beyond that seen following homotypic stress exposure. In contrast, unpredictable stress did not result in decreased activation of any structures showing FosB induction by repeated restraint, suggesting that regions are not “de-recruited” (Flak et al., 2012). Thus, it is evident that unpredictable stress recruits regions not engaged by the habituating regimen, consistent with usage of distinct circuits under the two conditions.
