Crick-Jacobs Center for Theoretical and Computational Biology, Salk Institute for Biological Studies, La Jolla, California 92037, USA.
J Neurosci. 2010 Feb 10;30(6):2150-9. doi: 10.1523/JNEUROSCI.4818-09.2010.
Neocortical networks are composed of diverse populations of cells that differ in their chemical content, electrophysiological characteristics, and connectivity. Gamma-frequency oscillatory activity of inhibitory subnetworks has been hypothesized to regulate information processing in the cortex as a whole. Inhibitory neurons in these subnetworks synchronize their firing and selectively innervate the perisomatic compartments of their target neurons, generating both tonic and rapidly fluctuating inhibition. How do different types of cortical neurons respond to changes in the level and structure of perisomatic inhibition? What accounts for response heterogeneity between cell types, and are these response properties fixed or flexible? To answer these questions, we use in vitro whole-cell recording and dynamic-clamp somatic current injection to study six distinct types of cortical neurons. We demonstrate that different types of neurons systematically vary in their receptiveness to fast changes in the structure of inhibition and the range over which changes in inhibitory tone affect their output. Using simple neuron models and model neuron hybrids (dynamic clamp), we determine which intrinsic differences between cell types lead to these variations in receptiveness. These results suggest important differences in the way cell types are affected by gamma-frequency inhibition, which may have important circuit level implications. Although intrinsic differences observed in vitro are useful for the elucidation of basic cellular properties and differences between cell types, we also investigate how the integrative properties of neurons are likely to be rapidly modulated in the context of active networks in vivo.
新皮层网络由多种细胞组成，这些细胞在化学物质含量、电生理特性和连接方式上存在差异。抑制性亚网络的伽马频率振荡活动被假设为调节整个皮层的信息处理。这些亚网络中的抑制性神经元同步其放电，并选择性地支配其靶神经元的体周区室，产生紧张性和快速波动的抑制。不同类型的皮层神经元如何对体周抑制水平和结构的变化做出反应？细胞类型之间的反应异质性是由什么引起的，这些反应特性是固定的还是灵活的？为了回答这些问题，我们使用体外全细胞记录和动态箝位体细胞电流注入来研究六种不同类型的皮层神经元。我们证明，不同类型的神经元在对抑制结构的快速变化以及抑制音调变化影响其输出的范围的敏感性方面存在系统差异。使用简单的神经元模型和模型神经元杂交体（动态箝位），我们确定了细胞类型之间的哪些内在差异导致了这种敏感性的差异。这些结果表明，细胞类型受伽马频率抑制的影响方式存在重要差异，这可能对电路水平具有重要意义。尽管体外观察到的内在差异对于阐明基本的细胞特性和细胞类型之间的差异很有用，但我们也研究了在体内活跃网络的背景下，神经元的整合特性如何可能被快速调节。
