Departament de Biologia Funcional i Antropologia Física, Facultat de Ciències Biològiques, Universitat de València València, Spain.
Front Neuroanat. 2011 Aug 22;5:54. doi: 10.3389/fnana.2011.00054. eCollection 2011.
Rodents constitute good models for studying the neural basis of sociosexual behavior. Recent findings in mice have revealed the molecular identity of the some pheromonal molecules triggering intersexual attraction. However, the neural pathways mediating this basic sociosexual behavior remain elusive. Since previous work indicates that the dopaminergic tegmento-striatal pathway is not involved in pheromone reward, the present report explores alternative pathways linking the vomeronasal system with the tegmento-striatal system (the limbic basal ganglia) by means of tract-tracing experiments studying direct and indirect projections from the chemosensory amygdala to the ventral striato-pallidum. Amygdaloid projections to the nucleus accumbens, olfactory tubercle, and adjoining structures are studied by analyzing the retrograde transport in the amygdala from dextran amine and fluorogold injections in the ventral striatum, as well as the anterograde labeling found in the ventral striato-pallidum after dextran amine injections in the amygdala. This combination of anterograde and retrograde tracing experiments reveals direct projections from the vomeronasal cortex to the ventral striato-pallidum, as well as indirect projections through different nuclei of the basolateral amygdala. Direct projections innervate mainly the olfactory tubercle and the islands of Calleja, whereas indirect projections are more widespread and reach the same structures and the shell and core of nucleus accumbens. These pathways are likely to mediate innate responses to pheromones (direct projections) and conditioned responses to associated chemosensory and non-chemosensory stimuli (indirect projections). Comparative studies indicate that similar connections are present in all the studied amniote vertebrates and might constitute the basic circuitry for emotional responses to conspecifics in most vertebrates, including humans.
啮齿动物是研究社交行为神经基础的良好模型。最近在小鼠中的发现揭示了触发两性吸引的一些信息素分子的分子特征。然而，介导这种基本社交行为的神经通路仍不清楚。由于先前的工作表明多巴胺能被盖-纹状体通路不参与信息素奖励，本报告通过追踪实验探索了连接犁鼻器系统与被盖-纹状体系统（边缘基底神经节）的替代途径，该实验研究了从化学感觉杏仁核到腹侧纹状体-苍白球的直接和间接投射。通过分析腹侧纹状体中 Dextran 胺和氟金葡素注射后杏仁核中的逆行转运，以及 Dextran 胺注射后腹侧纹状体-苍白球中的顺行标记，研究了杏仁核向伏隔核、嗅结节和毗邻结构的投射。这种顺行和逆行追踪实验的结合揭示了来自犁鼻皮质的直接投射到腹侧纹状体-苍白球，以及通过不同的基底外侧杏仁核核的间接投射。直接投射主要支配嗅结节和卡列加岛，而间接投射则更为广泛，到达相同的结构和伏隔核的壳和核。这些途径可能介导对信息素的先天反应（直接投射）和对相关化学感觉和非化学感觉刺激的条件反应（间接投射）。比较研究表明，在所有研究的羊膜动物中都存在类似的连接，并且可能构成大多数脊椎动物（包括人类）对同种动物的情感反应的基本回路。
