GABAergic inactivation of basolateral amygdala alters behavioral processes other than primary reward of ventral tegmental self-stimulation

Although recent work on amygdalar function has concentrated on a role in fear and anxiety, a possible role in reward processes continues to be considered. This function may occur via anatomical connections between the basolateral amygdala (BLA) and the mesoaccumbens dopamine (DA) system (i.e., ventral tegmental area [VTA] to nucleus accumbens septi [NAS]), particularly at the level of the NAS. The current experiments investigated a possible role of the BLA in the reward of intracranial self-stimulation (ICSS) of the VTA. Rats were trained in either an autotitration ICSS task or a rate-frequency ICSS task. We examined the effect of intra-BLA injections of muscimol, a GABA(A) agonist which inhibits the firing of most neurons, on VTA ICSS in both behavioral procedures. The injections produced a pattern of behavioral change which, across the two tasks, was more consistent with a change in behavioral processes other than primary reward. Possible processes include cost/benefit analysis and incentive motivation. (c) 2007 Elsevier B.V. All rights reserved.