美国纽约大学神经科学中心Simon Peron研究组最新研究取得进展。他们发现局部皮质回路中的循环相互作用。这一研究成果发表在2020年3月4日出版的《自然》杂志上。

他们使用计算建模、光学记录和操作来探测反复耦联功能，这主要发生在小鼠主动触觉辨别过程中的可触性体感皮层的2/3层。第2/3层的神经回路模型显示，循环激励通过放大增强感觉信号，但仅适用于连接性增强的子网。具有高放大倍率的模型网络对伤害敏感：子网中几个成员的丢失会降低刺激编码。他们通过绘制具有特定选择性的神经元选择性和光漂白神经元来测试此预测。在备用触摸表示中，一小部分表示触摸的第2/3层神经元的消融（10–20，少于总数的5％）显著降低响应，但在其他表示中却没有。消融对神经元的影响最大，其刺激响应与消融群体相似，这也与网络模型一致。因此，具有相似选择性的皮质神经元之间的循环会在行动过程中驱动输入特定的扩增。

据了解，大多数皮质突触是局部的和兴奋性的。局部环路可以实现放大，从而允许模式完成和其他计算。皮层回路包含的子网络由神经元组成，这些神经元具有相似的接受场，并且相对于网络平均值而言，连接性增加。编码不同类型信息的皮质神经元在空间上整合并分布在大量脑中，通过分别干扰它们来探测这些子网功能的尝试，被这种复杂性所阻碍。

附：英文原文

Title: Recurrent interactions in local cortical circuits

Author: Simon Peron, Ravi Pancholi, Bettina Voelcker, Jason D. Wittenbach, H. Freyja lafsdttir, Jeremy Freeman, Karel Svoboda

Issue&Volume: 2020-03-04

Abstract: Most cortical synapses are local and excitatory. Local recurrent circuits could implement amplification, allowing pattern completion and other computations1,2,3,4. Cortical circuits contain subnetworks that consist of neurons with similar receptive fields and increased connectivity relative to the network average5,6. Cortical neurons that encode different types of information are spatially intermingled and distributed over large brain volumes5,6,7, and this complexity has hindered attempts to probe the function of these subnetworks by perturbing them individually8. Here we use computational modelling, optical recordings and manipulations to probe the function of recurrent coupling in layer 2/3 of the mouse vibrissal somatosensory cortex during active tactile discrimination. A neural circuit model of layer 2/3 revealed that recurrent excitation enhances sensory signals by amplification, but only for subnetworks with increased connectivity. Model networks with high amplification were sensitive to damage: loss of a few members of the subnetwork degraded stimulus encoding. We tested this prediction by mapping neuronal selectivity7 and photoablating9,10 neurons with specific selectivity. Ablation of a small proportion of layer 2/3 neurons (10–20, less than 5% of the total) representing touch markedly reduced responses in the spared touch representation, but not in other representations. Ablations most strongly affected neurons with stimulus responses that were similar to those of the ablated population, which is also consistent with network models. Recurrence among cortical neurons with similar selectivity therefore drives input-specific amplification during behaviour.

DOI: 10.1038/s41586-020-2062-x

Source: https://www.nature.com/articles/s41586-020-2062-x