Exploring links from sensory perception to movement and behavioral motivation in the caudal nidopallium of female songbirds.

Decision making resides at the interface between sensory perception and movement production. Female songbirds in the context of mate choice are an excellent system to define neural circuits through which sensory perception influences production of courtship behaviors. Previous experiments by our group and others have implicated secondary auditory brain sites, including the caudal nidopallium (NC), in mediating behavioral indicators of mate choice. Here, we used anterograde tracer molecules to define projections that emerge from NC in female songbirds, identifying pathways through which NC influences downstream sites implicated in signal processing and decision making. Our results reveal that NC sends projections into the arcopallium, including the ventral intermediate arcopallium (AIV). Previous work revealed that AIV also receives input from another auditory area implicated in song preference and mate choice (caudal mesopallium, CM), suggesting that convergent input from multiple auditory areas may play important roles in initiating mate choice behaviors. In the present results, NC projects to an area implicated in postural and locomotory control (dorsal arcopallium, Ad), suggesting that NC may play a role in directing those forms of copulatory behavior. NC projections also systematically avoid a vocal motor region of the arcopallium that is innervated by CM (robust nucleus of the arcopallium). These results suggest a model in which both NC and CM project to arcopallial pathways implicated in behavioral motivation. These brain regions may exert different influences on pathways through which auditory information can direct different facets of behavioral responses to information detected in those auditory signals.