Representation of Olfactory Information in Organized Active Neural Ensembles in the Hypothalamus

The internal representation of sensory information via coherent activation of specific pathways in the nervous system is key to appropriate behavioral responses. Little is known about how chemical stimuli that elicit instinctive behaviors lead to organized patterns of activity in the hypothalamus. Here, we study how a wide range of chemosignals form a discernible map of olfactory information in the ventromedial nucleus of the hypothalamus (VMH) and show that different stimuli entail distinct active neural ensembles. Importantly, we demonstrate that this map depends on functional inputs from the vomeronasal organ. We present evidence that the spatial locations of active VMH ensembles are correlated with activation of distinct vomeronasal receptors and that disjunct VMH ensembles exhibit differential projection patterns. Moreover, active ensembles with distinct spatial locations are not necessarily associated with different behavior categories, such as defensive or social, calling for a revision of the currently accepted model of VMH organization. [Display omitted] •Different stimuli lead to distinct spatial patterns of active VMH neurons•Representation of olfactory information in the VMH is dependent on vomeronasal input•Activated vomeronasal receptors correlate with the location of active VMH ensembles•Distinct VMH ensembles are associated with different output projection patterns Carvalho et al. find that mice exposed to different odors display activation of distinctly located neurons in the ventromedial nucleus of the hypothalamus in the brain. The spatial location of activated neurons depends on the vomeronasal organ in the nose and correlates with its activated sensory receptors.