Enhanced passive avoidance learning and appetitive T-maze learning with post-trial rewarding hypothalamic stimulation.

Experiments were carried out to investigate the effects of post-trial reinforcing stimulation of the lateral hypothalamus on learning in rats. The reinforcing stimulation was always presented for a duration of 20--30 sec (0.2 sec on/0.8 sec off), and was administered either immediately, 30 sec delayed or 300 sec delayed after exposure to the learning situation. In experiment 1 post-trial stimulation led to improved passive avoidance learning of an alcove-avoidance task when presented 30 sec compared to immediately after the footshock. In Experiment 2 reversal learning of a one-way shuttle-box avoidance task was facilitated by 30 sec delayed, but not 300 sec delayed post-trial reinforcing stimulation. In Experiment 3 appetitive left-right discrimination was investigated using a T-maze task. Thirty sec delayed post-trial reinforcing stimulation presented contingent on errors facilitated learning of this task. Together, the 3 studies provide further support for the hypothesis that reinforcers directly influence labile memory processes (such as short-term memory) and thereby improve learning.