DEPRIVATION ENHANCES FEAR CONDITIONING TO CONTEXTUAL, BUT NOT DISCRETE, CONDITIONAL STIMULI IN RATS

Water-deprived and nondeprived rats were fear conditioned with a discr ete tone conditional stimulus (CS) and an aversive footshock unconditi onal stimulus (US). Twenty-four and 48 hr following conditioning, cond itional fear to the tone CS and the context cues of the conditioning c hamber, respectively, were assessed by measuring freezing behavior. Wa ter deprivation had no effect on baseline responding to either tone or contextual stimuli. Following either 1 or 3 tone-shock pairings, howe ver, water deprivation selectively enhanced conditional freezing to th e contextual cues of the training chamber; conditional freezing to the tone was unaffected by water deprivation. These results are consisten t with the view that water deprivation affects fear conditioning via a n influence on the hippocampus.