S9-9 Wed Jan 6 16:30 – 17:00 Neuromodulatory feedback to sensory systems: how serotonin conveys contextual information to the auditory midbrain Petersen , CL; Hurley, LM*; University of Minnesota Twin Cities; Indiana University email@example.com
Context is an important source of information that allows animals to appropriately respond to social signals. In a mouse model of vocal communication, broadly defined aspects of context such as the identity of social partners, internal state, and prior social experience converge to influence how the serotonergic system interacts with auditory brain regions. Serotonin may therefore be one source of contextual information in the auditory system, but the functional consequences of this interaction have not been well-explored. To further understand the functional anatomy of auditory-projecting serotonergic neurons, tract tracers were injected into the inferior colliculus (IC) in the auditory midbrain. The dorsal raphe nucleus (DRN) was then imaged in conjunction with immunohistochemistry for a synthetic enzyme for serotonin, tryptophan hydroxylase (TPH), and for the immediate early gene c-Fos. Males and females were compared following interaction with a member of the opposite sex, or confinement in a small area. Neurons double-labeled for tract tracer and TPH were found in two distinct subregions of the DRN. Males had a higher number of double-labeled neurons than females, suggesting a sexually dimorphic serotonergic projection to the auditory midbrain. Further, we found that the number of TPH/c-Fos positive neurons were correlated with behavior during social interaction in females, but not males. The direction of the correlation was opposite within different DRN subregions, suggesting that activity in DRN subregions may vary across social context.