Laboratorio de Neuroanatomía, Departamento de Anatomía, and Centro Interdisciplinario de Neurociencia, NeuroUC, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.
Institute of Neurophysiology, Goethe University, Frankfurt, Germany.
Front Neural Circuits. 2021 Nov 19;15:769342. doi: 10.3389/fncir.2021.769342. eCollection 2021.
The firing activity of ventral tegmental area (VTA) and substantia nigra pars compacta (SNc) dopaminergic (DA) neurons is an important factor in shaping DA release and its role in motivated behavior. Dendrites in DA neurons are the main postsynaptic compartment and, along with cell body and axon initial segment, contribute to action potential generation and firing pattern. In this study, the organization of the dendritic domain in individual VTA and SNc DA neurons of adult male mice, and their relationship to spontaneous firing, are described. In comparison with dorsal VTA DA neurons, ventrally located VTA neurons (as measured by cell body location) possess a shorter total dendritic length and simpler dendritic architecture, and exhibit the most irregular firing patterns among DA neurons. In contrast, for DA neurons in the SNc, the higher irregularity of firing was related to a smaller dendritic domain, as measured by convex hull volumes. However, firing properties were also related to the specific regional distribution of the dendritic tree. Thus, VTA DA neurons with a larger extension of their dendritic tree within the parabrachial pigmented (PBP) nucleus fired more regularly compared with those with relatively more dendrites extending outside the PBP. For DA neurons in the SNc, enhanced firing irregularity was associated with a smaller proportion of dendrites penetrating the substantia nigra pars reticulata. These results suggest that differences in dendritic morphology contribute to the firing properties of individual DA neurons, and that the existence of region-specific synaptic connectivity rules that shape firing diversity.
腹侧被盖区（VTA）和黑质致密部（SNc）多巴胺能（DA）神经元的放电活动是塑造 DA 释放及其在动机行为中的作用的重要因素。DA 神经元的树突是主要的突触后区，与细胞体和轴突起始段一起，有助于动作电位的产生和放电模式。在这项研究中，描述了成年雄性小鼠单个 VTA 和 SNc DA 神经元的树突域的组织及其与自发放电的关系。与背侧 VTA DA 神经元相比，位于腹侧的 VTA 神经元（以细胞体位置测量）具有较短的总树突长度和较简单的树突结构，并且在 DA 神经元中表现出最不规则的放电模式。相比之下，对于 SNc 中的 DA 神经元，不规则性更高的放电与较小的树突域有关，如凸包体积所示。然而，放电特性也与树突树的特定区域分布有关。因此，与那些相对更多的树突延伸到 PBP 之外的 VTA DA 神经元相比，在 PBP 内其树突延伸更大的 VTA DA 神经元的放电更规则。对于 SNc 中的 DA 神经元，不规则性增强的放电与穿透黑质网状部的树突比例较小有关。这些结果表明，树突形态的差异有助于单个 DA 神经元的放电特性，并且存在特定于区域的突触连接规则，这些规则塑造了放电多样性。
