The role of genetically distinct central amygdala neurons in appetitive and aversive responding assayed with a novel dual valence operant conditioning paradigm.

Abstract

To survive, animals must meet their biological needs while simultaneously avoiding danger. However, the neurobiological basis of appetitive and aversive survival behaviors has historically been studied using separate behavioral tasks. While recent studies in mice have quantified appetitive and aversive conditioned responses simultaneously (Heinz et al., 2017; Jikomes et al., 2016), these tasks required different behavioral responses to each stimulus. As many brain regions involved in survival behavior process stimuli of opposite valence, we developed a paradigm in which mice perform the same response (nosepoke) to distinct auditory cues to obtain a rewarding outcome (palatable food) or avoid an aversive outcome (mild footshoock). This design allows for both within- and between-subject comparisons as animals respond to appetitive and aversive cues. The central nucleus of the amygdala (CeA) is implicated in the regulation of responses to stimuli of either valence. Considering its role in threat processing (Haubensak et al., 2010; Wilensky et al., 2006) and regulation of incentive salience (Warlow and Berridge, 2021), it is important to examine the contribution of the CeA to mechanisms potentially underlying comorbid dysregulation of avoidance and reward (Bolton et al., 2009; Sinha, 2008). Using this paradigm, we tested the role of two molecularly defined CeA subtypes previously linked to consummatory and defensive behaviors. Significant strain differences in the acquisition and performance of the task were observed. Bidirectional chemogenetic manipulation of CeA somatostatin (SOM) neurons altered motivation for reward and perseveration of reward-seeking responses on avoidance trials. Manipulation of corticotropin-releasing factor neurons (CRF) had no significant effect on food reward consumption, motivation, or task performance. This paradigm will facilitate investigations into the neuronal mechanisms controlling motivated behavior across valences. Significance StatementIt is unclear how different neuronal populations contribute to reward- and aversion-driven behaviors within a subject. To address this question, we developed a novel behavioral paradigm in which mice obtain food and avoid footshocks via the same operant response. We then use this paradigm to test how the central amygdala coordinates appetitive and aversive behavioral responses. By testing somatostatin-IRES-Cre and CRF-IRES-Cre transgenic lines, we found significant differences between strains on task acquisition and performance. Using chemogenetics, we demonstrate that CeA SOM+ neurons regulate motivation for reward, while manipulation of CeA CRF+ neurons had no effect on task performance. Future studies investigating the interaction between positive and negative motivation circuits should benefit from the use of this dual valence paradigm.