Synthesis of a comprehensive population code for contextual features in the awake sensory cortex.
Synthesis of a comprehensive population code for contextual features in the awake sensory cortex.
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DOI：
10.7554/elife.62687
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发表时间：
2021-11-01
期刊：
影响因子：
7.7
通讯作者：
Adesnik H
中科院分区：
文献类型：
--
作者：
Lyall EH;Mossing DP;Pluta SR;Chu YW;Dudai A;Adesnik H
皮质回路如何构建复杂物体的表征还知之甚少。单个神经元必须在空间上广泛整合，但同时获得对特定全局刺激特征的急剧调谐。然后，识别不同全局特征的神经元组必须组装成一个群体，形成这些全局刺激属性的综合代码。虽然在麻醉动物中，单个神经元如何在空间输入上求和的逻辑已经得到了很好的探索，但在清醒的动物中，大群神经元如何组成一个灵活的高阶特征群体代码还不清楚。为了解决这个问题，我们探讨了整合和群体编码的高阶刺激清醒小鼠的体感和视觉皮层使用双光子钙成像跨皮层层。我们开发了一种新型的触觉刺激器，即使在积极搅拌小鼠中也可以精确测量空间总和。使用这个系统，我们发现了一个稀疏的，但全面的人口代码高阶触觉功能，依赖于一个异构的和神经元特异性的逻辑空间总和超出了感受野。不同的躯体感觉皮层神经元超线性地总结感觉输入的特定组合，但次线性地整合其他输入，导致对高阶特征的选择性反应。视觉皮层人群采用了几乎相同的计划，以产生一个全面的人口代码的上下文刺激。这些结果表明，输入特定的超线性求和的异质逻辑可能代表了一个广泛的皮质机制，用于在神经种群中合成稀疏高阶特征代码。这可能解释了大脑如何利用丘脑皮层的维度扩张来编码感官刺激的任意复杂特征。
How cortical circuits build representations of complex objects is poorly understood. Individual neurons must integrate broadly over space, yet simultaneously obtain sharp tuning to specific global stimulus features. Groups of neurons identifying different global features must then assemble into a population that forms a comprehensive code for these global stimulus properties. Although the logic for how single neurons summate over their spatial inputs has been well explored in anesthetized animals, how large groups of neurons compose a flexible population code of higher-order features in awake animals is not known. To address this question, we probed the integration and population coding of higher-order stimuli in the somatosensory and visual cortices of awake mice using two-photon calcium imaging across cortical layers. We developed a novel tactile stimulator that allowed the precise measurement of spatial summation even in actively whisking mice. Using this system, we found a sparse but comprehensive population code for higher-order tactile features that depends on a heterogeneous and neuron-specific logic of spatial summation beyond the receptive field. Different somatosensory cortical neurons summed specific combinations of sensory inputs supra-linearly, but integrated other inputs sub-linearly, leading to selective responses to higher-order features. Visual cortical populations employed a nearly identical scheme to generate a comprehensive population code for contextual stimuli. These results suggest that a heterogeneous logic of input-specific supra-linear summation may represent a widespread cortical mechanism for the synthesis of sparse higher-order feature codes in neural populations. This may explain how the brain exploits the thalamocortical expansion of dimensionality to encode arbitrary complex features of sensory stimuli.