Martiel J L, Mouchet P, Boissier M D
Techniques de l'Imagerie et de la Modelisation en Cognisciences, URA CNRS 1618, La Tronche, France.
Synapse. 1994 Apr;16(4):269-79. doi: 10.1002/syn.890160404.
The role of the striatum in the control of movements and in the processing of cortical information has received much attention in the recent years. We set out a simple biophysical model for the medium-spiny neuron (msn), the most abundant cell in striatum. This neuron receives two main kinds of inputs, namely, cortical excitatory inputs and dopaminergic inputs coming from the substantia nigra pars compacta. The msn axon impinges directly onto the globus pallidus and onto the substantia nigra pars reticulata neurons and onto striatal neurons through recurrent branches of the axon. The msn is characterized by spiny dendritic trees with a high density of spines (1 to 4 spines/microns) and the probable existence of dendritic spikes. The model predicts that the neuron can integrate excitable inputs in a linear or a nonlinear mode. In the nonlinear mode, the neuron allows the detection of simultaneous (or almost simultaneous) synaptic inputs; it facilitates either a slowing down or a speeding up of the information transfer between the synaptic input location and the soma and is sensitive to inhibiton-excitation pairing. Conversely, in the linear integrative mode, the somatic voltage is determined by a weighted summation of the synaptic inputs. Several geometrical, electrical, or temporal factors can control the switch between these behaviors: the density of excitable dendritic elements, the dendritic radius, the resistance of the spine stem, the membrane resistance, the time between excitations, and the distance between synaptic sites. Finally, the signification of this behavior is discussed in connection with the putative role of dopamine and with the striatal net organization.
近年来，纹状体在运动控制和皮层信息处理中的作用备受关注。我们构建了一个简单的生物物理模型，用于研究中等多棘神经元（msn），这是纹状体中最丰富的细胞类型。该神经元接收两种主要输入，即来自皮层的兴奋性输入和来自黑质致密部的多巴胺能输入。msn轴突直接投射到苍白球、黑质网状部神经元以及通过轴突的回返分支投射到纹状体神经元。msn的特征是具有高密度棘突（1至4个棘突/微米）的多棘树突以及可能存在的树突棘。该模型预测，该神经元能够以线性或非线性模式整合兴奋性输入。在非线性模式下，神经元允许检测同时（或几乎同时）的突触输入；它促进了突触输入位置与胞体之间信息传递的减慢或加速，并且对抑制 - 兴奋配对敏感。相反，在线性整合模式下，体细胞电压由突触输入的加权总和决定。几个几何、电学或时间因素可以控制这些行为之间的转换：兴奋性树突元件的密度、树突半径、棘突柄的电阻、膜电阻、兴奋之间的时间以及突触位点之间的距离。最后，结合多巴胺的假定作用和纹状体网络组织对这种行为的意义进行了讨论。
