IntroductionThe basal ganglia (BG) are involved in motor control and play an essential role in movement disorders such as hemiballismus, dystonia, and Parkinson's disease. Neurons in the motor part of the BG respond to passive movement or stimulation of different body parts and to stimulation of corresponding cortical regions. Experimental evidence suggests that the BG are organized somatotopically, i.e., specific areas of the body are associated with specific regions in the BG nuclei. Signals related to the same body part that propagate along different pathways converge onto the same BG neurons, leading to characteristic shapes of cortically evoked responses. This suggests the existence of functional channels that allow for the processing of different motor commands or information related to different body parts in parallel. Neurological disorders such as Parkinson's disease are associated with pathological activity in the BG and impaired synaptic connectivity, together with reorganization of somatotopic maps. One hypothesis is that motor symptoms are, at least partly, caused by an impairment of network structure perturbing the organization of functional channels.MethodsWe developed a computational model of the STN-GPe circuit, a central part of the BG. By removing individual synaptic connections, we analyzed the contribution of signals propagating along different pathways to cortically evoked responses. We studied how evoked responses are affected by systematic changes in the network structure. To quantify the BG's organization in the form of functional channels, we suggested a two-site stimulation protocol.ResultsOur model reproduced the cortically evoked responses of STN and GPe neurons and the contributions of different pathways suggested by experimental studies. Cortical stimulation evokes spatio-temporal response patterns that are linked to the underlying synaptic network structure. Our two-site stimulation protocol yielded an approximate functional channel width.Discussion/conclusionThe presented results provide insight into the organization of BG synaptic connectivity, which is important for the development of computational models. The synaptic network structure strongly affects the processing of cortical signals and may impact the generation of pathological rhythms. Our work may motivate further experiments to analyze the network structure of BG nuclei and their organization in functional channels.

中文翻译：

---

突触网络结构在计算模型中塑造 STN 和 GPe 神经元的皮质诱发时空反应

简介基底神经节 (BG) 参与运动控制，并在偏侧运动、肌张力障碍和帕金森病等运动障碍中发挥重要作用。BG 运动部分的神经元对不同身体部位的被动运动或刺激以及相应皮质区域的刺激做出反应。实验证据表明 BG 是按体位组织的，即身体的特定区域与 BG 核中的特定区域相关。与同一身体部位相关的信号沿着不同的通路传播，汇聚到相同的 BG 神经元上，从而导致皮质诱发反应的特征形状。这表明存在功能通道，允许并行处理不同的运动命令或与不同身体部位相关的信息。帕金森病等神经系统疾病与 BG 的病理活动和突触连接受损以及体位图的重组有关。一种假设是，运动症状至少部分是由扰乱功能通道组织的网络结构损伤引起的。方法我们开发了 STN-GPe 回路（BG 的核心部分）的计算模型。通过去除单个突触连接，我们分析了沿不同途径传播的信号对皮质诱发反应的贡献。我们研究了网络结构的系统变化如何影响诱发反应。为了以功能通道的形式量化 BG 的组织，我们提出了一种双位点刺激方案。结果我们的模型再现了 STN 和 GPe 神经元的皮质诱发反应以及实验研究表明的不同途径的贡献。皮质刺激引起与潜在突触网络结构相关的时空反应模式。我们的两点刺激方案产生了近似的功能通道宽度。讨论/结论所提出的结果提供了对 BG 突触连接组织的深入了解，这对于计算模型的开发非常重要。突触网络结构强烈影响皮质信号的处理，并可能影响病理节律的产生。我们的工作可能会激发进一步的实验来分析 BG 核的网络结构及其在功能通道中的组织。