Cell Assembly Dynamics of Sparsely-Connected Inhibitory Networks: A Simple Model for the Collective Activity of Striatal Projection Neurons

Striatal projection neurons form a sparsely-connected inhibitory network, and this arrangement may be essential for the appropriate temporal organization of behavior. Here we show that a simplified, sparse inhibitory network of Leaky-Integrate-and-Fire neurons can reproduce some key features of striatal population activity, as observed in brain slices. In particular we develop a new metric to determine the conditions under which sparse inhibitory networks form anti-correlated cell assemblies with time-varying activity of individual cells. We find that under these conditions the network displays an input-specific sequence of cell assembly switching, that effectively discriminates similar inputs. Our results support the proposal that GABAergic connections between striatal projection neurons allow stimulus-selective, temporally-extended sequential activation of cell assemblies. Furthermore, we help to show how altered intrastriatal GABAergic signaling may produce aberrant network-level information processing in disorders such as Parkinson’s and Huntington’s diseases.纹状体投射神经元（striatal projection neurons）构成稀疏连接的抑制性神经网络，该结构或对行为的恰当时序组织至关重要。本研究发现，简化版的漏积分-放电神经元（Leaky-Integrate-and-Fire neurons）稀疏抑制网络可复现脑切片中观测到的纹状体群体活动的部分关键特征。具体而言，我们开发了一种全新的量化指标，用于确定稀疏抑制网络形成具备个体神经元活动时变特性的反相关细胞集群（cell assemblies）的条件。研究表明，在该条件下网络会呈现输入特异性的细胞集群切换序列，可有效区分相似输入信号。本结果支持如下假说：纹状体投射神经元间的γ-氨基丁酸能（GABAergic）连接可实现细胞集群的刺激选择性、时序延展的顺序激活。此外，本研究还阐明了纹状体内部γ-氨基丁酸能信号异常如何引发帕金森病（Parkinson’s disease）、亨廷顿病（Huntington’s disease）等疾病中异常的网络层面信息处理过程。