ENHANCED RETRIEVAL OF UNPLEASANT MEMORIES INFLUENCED BY SHOCK CONTROLLABILITY, SHOCK SEQUENCE, AND RAT STRAIN

The propensity to recall unpleasant events may be related to depressio n and posttraumatic stress disorder. This study examined the extent to which the recall of a previously unpleasant event (i.e., passive avoi dance training) may be influenced by another aversive event. The other aversive event was tail shock. Since the Wistar Kyoto (WKY) rat strai n has been proposed as an animal model of depressive behavior, this st udy was conducted with WKY and Wistar rats. Parameters manipulated inc luded shock controllability, shock sequence (i.e., tail shock before a voidance training versus tail shock after training), and rat strain. P erformance of the passive avoidance (PA) response was greater in WKY r ats, Exposure to inescapable tail shock was related to greater PA perf ormance compared to exposure to escapable or no-shock treatments. Tail shock prior to PA training led to greater recall of the PA response. The magnitude of-the PA response was influenced by the rat strain, sho ck controllability, and shock sequence, The applicability of these dat a to the memory bias phenomenon in depression is discussed.