Dissecting the determinants of decisions: Sex differences and distributed reinforcement revealed in a rat choice task

Abstract

Decision-making in the mammalian brain involves structures within the midbrain, striatum, limbic system, and cortex. My colleagues and I studied the roles of several of these structures in reward-processing and decision-making related phenomena. First, we found female rats were more likely to approach feeders outside the task context in an operant chamber with two feeders. I speculate this sexual dimorphism relates to the disproportionate effect of fasting on reproduction in female rats; this provides an alternative to the widespread interpretation that male rats are more risk-seeking than females. Next, we recorded field potentials (FPs) from seven brain regions as rats completed a binary choice task to determine if reward information originated in a particular area, and if the fidelity of information varied among them. Using a machine learning classifier, we found reinforcement information was distributed across the network and there was no canonical flow of information in the recorded structures.