Figure 1.

Anatomy of the AOS and layout of the preparation. A, Primary sensory neurons located in the VNO send their axons to the AOB, where they make contact with second order sensory neurons; >90% of these second order sensory neurons project to the vomeronasal amygdala, where their output is integrated with that of other sensory systems (Swanson and Petrovich, 1998) and used to guide behavior, including the neuroendocrine output of the hypothalamus. Stimuli were delivered through a tube inserted into the lumen of the VNO. Recordings were performed through a craniotomy; pharmacological agents were supplied through the solution superfusing the cavity. B, The AOB contains two layers of laterally inhibitory connections: the synaptic contacts between primary (VRN) and secondary (MC) sensory neurons are organized into glomerular structures (GL) which are partially ensheathed by GABAergic periglomerular cells (PG). More numerous than the periglomerular cells are the GABAergic granule cells (GC), which form reciprocal dendro-dendritic synapses onto both the lateral and, most often, the primary dendrites of the mitral cells.