The effect of post-training hypothalamic self-stimulation on sensory preconditioning in rats

58 male hooded water-deprived rats experienced a preconditioning session (consisting of paired or unpaired presentations of a tone and a light) followed by either no self-stimulation, immediate self-stimulation, or self-stimulation delayed by 2 or 4 hrs. On the next 2 days, Ss experienced the conditioning phase in which the light was paired with a footshock. 24 hrs after the last conditioning trial, the transfer of the conditioned emotional response from the light to the tone was evaluated using a suppression-of-drinking procedure. Self-stimulation facilitated retention of the association between the tone and the light when it occurred within 2 hrs after preconditioning training, but not when it occurred 4 hrs after training. Immediate posttraining self-stimulation had no effect on Ss that experienced unpaired tone and light presentations during preconditioning training. Data suggest that the self-stimulation treatment strengthened the association between the tone and the light retroactively and noncontingently, and show that direct activation of the neural substrate of reinforcement can improve memory for associations formed between 2 neutral stimuli. (French abstract) (34 ref)