Consistent rewarding or aversive effects of the electrical stimulation of the lateral parabrachial complex

Electrical stimulation of the external lateral parabrachial subnucleus (LPBe) may induce rewarding or aversive behaviors in animals subjected to two different learning discrimination tasks. Statistical analysis found no significant differences between the group receiving electrical stimulation of the brain and the non-stimulated control group. However, rewarding or aversive behaviors were consistent and positively correlated between the two discrimination tasks in the stimulated group. Thus, these tests differed in the gustatory stimuli used, in the right/left position of stimulation-associated/non-associated flavors, and in the cage in which experiments were performed. This behavioral consistency and corresponding correlation were not observed in the non-stimulated control group. These results suggest the existence of aversive and reward systems that are differentiated but anatomically very close. Therefore, the activation of aversive or rewarding systems may depend on the precise location of the electrode implanted in the LPBe of each animal.