The vomeronasal cortex – afferent and efferent projections of the posteromedial cortical nucleus of the amygdala in mice

Authors

  • Nicolás Gutiérrez-Castellanos,

    1. Laboratori de Neuroanatomia Funcional Comparada, Departaments de Biologia Cellular i de Biologia Funcional, Facultat de Ciències Biològiques, Universitat de València, Burjassot, València, Spain
    Current affiliation:
    1. Cerebellar coordination and Cognition Group, Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
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  • Cecília Pardo-Bellver,

    1. Laboratori de Neuroanatomia Funcional Comparada, Departaments de Biologia Cellular i de Biologia Funcional, Facultat de Ciències Biològiques, Universitat de València, Burjassot, València, Spain
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  • Fernando Martínez-García,

    1. Laboratori de Neuroanatomia Funcional Comparada, Departaments de Biologia Cellular i de Biologia Funcional, Facultat de Ciències Biològiques, Universitat de València, Burjassot, València, Spain
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  • Enrique Lanuza

    Corresponding author
    1. Laboratori de Neuroanatomia Funcional Comparada, Departaments de Biologia Cellular i de Biologia Funcional, Facultat de Ciències Biològiques, Universitat de València, Burjassot, València, Spain
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Abstract

Most mammals possess a vomeronasal system that detects predominantly chemical signals of biological relevance. Vomeronasal information is relayed to the accessory olfactory bulb (AOB), whose unique cortical target is the posteromedial cortical nucleus of the amygdala. This cortical structure should therefore be considered the primary vomeronasal cortex. In the present work, we describe the afferent and efferent connections of the posteromedial cortical nucleus of the amygdala in female mice, using anterograde (biotinylated dextranamines) and retrograde (Fluorogold) tracers, and zinc selenite as a tracer specific for zinc-enriched (putative glutamatergic) projections. The results show that the posteromedial cortical nucleus of the amygdala is strongly interconnected not only with the rest of the vomeronasal system (AOB and its target structures in the amygdala), but also with the olfactory system (piriform cortex, olfactory-recipient nuclei of the amygdala and entorhinal cortex). Therefore, the posteromedial cortical nucleus of the amygdala probably integrates olfactory and vomeronasal information. In addition, the posteromedial cortical nucleus of the amygdala shows moderate interconnections with the associative (basomedial) amygdala and with the ventral hippocampus, which may be involved in emotional and spatial learning (respectively) induced by chemical signals. Finally, the posteromedial cortical nucleus of the amygdala gives rise to zinc-enriched projections to the ventrolateral septum and the ventromedial striatum (including the medial islands of Calleja). This pattern of intracortical connections (with the olfactory cortex and hippocampus, mainly) and cortico-striatal excitatory projections (with the olfactory tubercle and septum) is consistent with its proposed nature as the primary vomeronasal cortex.

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