Integration of sensory and motor processing underlying social behaviour in túngara frogs

Abstract

Social decision making involves the perception and processing of social stimuli, the subsequent evaluation of that information in the context of the individual's internal and externalmilieus to produce a decision, and then culminates in behavioural output informed by that decision. We examined brain networks in an anuran communication systemthat relies on acoustic signals to guide simple, stereotypedmotor output.We used egr-1mRNA expression to measure neural activation in male tu'ngara frogs, Physalaemus pustulosus, following exposure to conspecific and heterospecific calls that evoke competitive or aggressive behaviour.We found that acoustically driven activation in auditory brainstem nuclei is transformed into activation related to sensory-motor interactions in the diencephalon, followed by motor-related activation in the telencephalon. Furthermore, under baseline conditions, brain nuclei typically have correlated egr-1mRNAlevels within brain divisions. Hearing conspecific advertisement calls increases correlations between anatomically distant brain divisions; no such effect was observed in response to calls that elicit aggressive behaviour.Neural correlates of social decision making thus take multiple forms: (i) a progressive shift from sensory to motor encoding from lower to higher stages of neural processing and (ii) the emergence of correlated activation patterns among sensory and motor regions in response to behaviourally relevant social cues.