Anatomical and functional study of the neurons of the medial amygdala that project to the bed nucleus of the stria terminalis, to the ventrolateral part of the ventromedial nucleus of the hypothalamus and to the ventral premammillary nucleus

Abstract

Disputes over resources and territory involving conspecifics are common in nature. In general, they cause significant negative consequences for both sides, so it is important to recognize the risk of conflicts with the rival for the best position to be taken. In these situations, defense behaviors such as flight, fight and freezing may be the most adequate survival strategy for the individual against a dominant conspecific. In this regard, it is not known exactly how a predominantly defensive behavior is naturally stimulated in terms of neural circuits. What is known, however, is that mice perceive conspecific information such as sex, competitive ability and reproductive status through pheromones. Furthermore, it is known that this information reaches the brain through the olfactory bulb and is subsequently processed by the medial nucleus of the amygdala (MeA). With that in mind, to improve our understanding of how social defense behavior is organized, this work proposes to study the projections of the MeA to the ventrolateral part of the ventromedial nucleus of the hypothalamus (VMHvl), to the ventral premammillary nucleus (PMV) and for the interstitial nucleus of the stria terminalis (BNST), which are interconnected structures that participate in the processing of conspecific cues and the social defense response. For this, a double retrograde and functional tracing study will be carried out in order to evaluate the activation of MeA neurons that project to the BNST, VMHvl and/or PMV, during social defense. From this, the work seeks to provide bases to understand how a defensive behavior is organized starting from the information acquired in the olfactory cues of the conspecific.