Contribution of the prefrontal cortex and basolateral amygdala to behavioral decision-making under reward/punishment conflict

Abstract

Rationale: Control of reward-seeking behavior under conditions of punishment is an important function for survival.

Objectives and methods: We designed a task in which rats could choose to either press a lever and obtain a food pellet accompanied by a footshock or refrain from pressing the lever to avoid footshock, in response to tone presentation. In the task, footshock intensity steadily increased, and the task was terminated when the lever press probability reached < 25% (last intensity). Rats were trained until the last intensity was stable. Subsequently, we investigated the effects of the pharmacological inactivation of the ventromedial prefrontal cortex (vmPFC), lateral orbitofrontal cortex (lOFC), and basolateral amygdala (BLA) on task performance.

Results: Bilateral inactivation of the vmPFC, lOFC, and BLA did not alter lever press responses at the early stage of the task. The number of lever presses increased following vmPFC and BLA inactivation but decreased following lOFC inactivation during the later stage of the task. The last intensity was elevated by vmPFC or BLA inactivation but lowered by lOFC inactivation. Disconnection of the vmPFC-BLA pathway induced behavioral alterations that were similar to vmPFC or BLA inactivation. Inactivation of any regions did not alter footshock sensitivity and anxiety levels.

Conclusions: Our results demonstrate a strong role of the vmPFC and BLA and their interactions in reward restraint to avoid punishment and a prominent role of the lOFC in reward-seeking under reward/punishment conflict situations.

Keywords: Basolateral amygdala; Lateral orbitofrontal cortex; Punishment; Reward; Ventromedial prefrontal cortex.