Department of Biology, Rhodes College, Memphis, TN 38112, USA; Program in Neuroscience, Rhodes College, Memphis, TN 38112, USA.
Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA.
Horm Behav. 2018 Nov;106:178-188. doi: 10.1016/j.yhbeh.2018.06.013. Epub 2018 Oct 26.
Animals have evolved flexible strategies that allow them to evaluate and respond to their social environment by integrating the salience of external stimuli with internal physiological cues into adaptive behavioral responses. A highly conserved social decision-making network (SDMN), consisting of interconnected social behavior and mesolimbic reward networks, has been proposed to underlie such adaptive behaviors across all vertebrates, although our understanding of this system in reptiles is very limited. Here we measure neural activation across the SDMN and associated regions in the male brown anole (Anolis sagrei), within both reproductive and agonistic contexts, by quantifying the expression density of the immediate early gene product Fos. We then relate this neural activity measure to social context, behavioral expression, and activation (as measured by colocalization with Fos) of different phenotypes of 'source' node neurons that produce neurotransmitters and neuropeptides known to modulate SDMN 'target' node activity. Our results demonstrate that measures of neural activation across the SDMN network are generally independent of specific behavioral output, although Fos induction in a few select nodes of the social behavior network component of the SDMN does vary with social environment and behavioral output. Under control conditions, the mesolimbic reward nodes of the SDMN actually correlate little with the social behavior nodes, but the interconnectivity of these SDMN components increases dramatically within a reproductive context. When relating behavioral output to specific source node activation profiles, we found that catecholaminergic activation is associated with the frequency and intensity of reproductive behavior output, as well as with aggression intensity. Finally, in terms of the effects of source node activation on SDMN activity, we found that Ile-oxytocin (mesotocin) populations correlate positively, while Ile-vasopressin (vasotocin), catecholamine, and serotonin populations correlate negatively with SDMN activity. Taken together, our findings present evidence for a highly dynamic SDMN in reptiles that is responsive to salient cues in a social context-dependent manner.
动物已经进化出灵活的策略，通过将外部刺激的显著性与内部生理线索整合到适应性行为反应中，来评估和响应它们的社会环境。一个高度保守的社会决策网络（SDMN），由相互连接的社会行为和中脑边缘奖励网络组成，被认为是所有脊椎动物这种适应性行为的基础，尽管我们对爬行动物中这个系统的理解非常有限。在这里，我们通过量化即时早期基因产物 Fos 的表达密度，来测量雄性棕色安乐蜥（Anolis sagrei）的 SDMN 及其相关区域在生殖和竞争两种情况下的神经激活。然后，我们将这种神经活动测量与社会背景、行为表现以及产生已知调节 SDMN“目标”节点活动的神经递质和神经肽的“源”节点神经元的不同表型的激活（如与 Fos 的共定位测量）相关联。我们的结果表明，SDMN 网络的神经激活测量通常与特定的行为输出无关，尽管 SDMN 社交行为网络成分中的少数几个节点的 Fos 诱导确实随社会环境和行为输出而变化。在对照条件下，SDMN 的中脑边缘奖励节点实际上与社交行为节点相关性很小，但这些 SDMN 成分的互连性在生殖环境中会显著增加。当将行为输出与特定的源节点激活模式相关联时，我们发现儿茶酚胺能激活与生殖行为输出的频率和强度以及攻击性强度相关。最后，就源节点激活对 SDMN 活动的影响而言，我们发现亮氨酸催产素（中脑催产素）群体呈正相关，而亮氨酸加压素（加压素）、儿茶酚胺和血清素群体与 SDMN 活动呈负相关。总之，我们的研究结果为依赖于社会环境的有明显线索的爬行动物中高度动态的 SDMN 提供了证据。
