Enhanced processing of an aversive memory following inescapable shock in rats

The aim of the present study was to determine the effect of inescapable shock on appetitive and aversive memory retrieval. Rats conditioned in a T-maze with appetitive (10% sucrose) and aversive (2.0 mA) events were subjected, respectively, to inescapable, escapable, and no-shock stress treatments. A retention test conducted 48 hr following exposure to stress treatments showed an enhanced avoidance behavior to enter a previously shocked goalbox with the absence of such a difference in responding to the nonshocked goalbox by the animals exposed to inescapable footshock stress. This differential response was not observed in two other groups, one given escapable footshock and the other no shock at all. This finding suggests memory processing is selectively enhanced in the helplessness condition and parallel to the retrieval bias that is evidenced in humans in depressive mood and induced helplessness.