Water deprivation enhances fear conditioning to contextual, but not discrete, conditional stimuli in rats

Water-deprived and nondeprived rats were fear conditioned with a discrete tone conditional stimulus (CS) and an aversive footshock unconditional stimulus (US). Twenty-four and 48 hr following conditioning, conditional fear to the tone CS and the context cues of the conditioning chamber, respectively, were assessed by measuring freezing behavior. Water deprivation had no effect on baseline responding to either tone or contextual stimuli. Following either 1 or 3 tone-shock pairings, however, water deprivation selectively enhanced conditional freezing to the contextual cues of the training chamber; conditional freezing to the tone was unaffected by water deprivation. These results are consistent with the view that water deprivation affects fear conditioning via an influence on the hippocampus.