Fundamental bounds on the fidelity of sensory cortical coding
Fundamental bounds on the fidelity of sensory cortical coding
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DOI：
10.1038/s41586-020-2130-2
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发表时间：
2020-03-18
期刊：
影响因子：
64.8
通讯作者：
Schnitzer, Mark J.
中科院分区：
文献类型：
--
作者：
Rumyantsev, Oleg I.;Lecoq, Jerome A.;Schnitzer, Mark J.
大脑如何在随机神经活动下准确处理信息是一个长期存在的问题(1)。例如，感知从根本上受到大脑从感觉神经元的嘈杂动态中提取的信息的限制。开创性的实验（2,3）表明，感觉皮质神经系统中的相关噪声限制了它们的编码准确性（4-6），尽管相关噪声如何影响神经编码仍存在争议（7-11）。最近的理论研究表明，与绝对噪声强度相比，神经系统整体的感官调谐特性与相关噪声模式的统计关系是编码准确性的更大决定因素（12-14）。然而，如果没有来自数千个共享感觉输入的皮质神经元的同时记录，相关噪声是否会限制编码的保真度是未知的。在这里，我们展示了一种16束双光子显微镜，用于监测小鼠初级视觉皮层的活动，以及对大型神经系统传递的信息进行量化分析。我们发现，在视觉皮层中，有800- 1300个神经元的集合具有相关的噪声约束信号。集合动力学的几个噪声成分与集合大小和编码的视觉信号成比例地增长，揭示了预测的信息限制相关性（12-14）。值得注意的是，视觉信号垂直于最大噪声模式，因此不会限制编码保真度。限制信息的噪声模式大约小10倍，与小鼠的视觉灵敏度一致（15）。因此，皮层设计原则似乎通过将约90%的噪声波动限制在不限制信号保真度的模式来提高编码精度，而更弱的相关噪声模式固有地束缚了感官辨别。一种能够同时记录小鼠视觉皮层数百个神经元的显微镜系统显示，大脑通过在垂直于相关噪声的维度上表示视觉输入来增强其编码能力。
How the brain processes information accurately despite stochastic neural activity is a longstanding question(1). For instance, perception is fundamentally limited by the information that the brain can extract from the noisy dynamics of sensory neurons. Seminal experiments(2,3) suggest that correlated noise in sensory cortical neural ensembles is what limits their coding accuracy(4-6), although how correlated noise affects neural codes remains debated(7-11). Recent theoretical work proposes that how a neural ensemble's sensory tuning properties relate statistically to its correlated noise patterns is a greater determinant of coding accuracy than is absolute noise strength(12-14). However, without simultaneous recordings from thousands of cortical neurons with shared sensory inputs, it is unknown whether correlated noise limits coding fidelity. Here we present a 16-beam, two-photon microscope to monitor activity across the mouse primary visual cortex, along with analyses to quantify the information conveyed by large neural ensembles. We found that, in the visual cortex, correlated noise constrained signalling for ensembles with 800-1,300 neurons. Several noise components of the ensemble dynamics grew proportionally to the ensemble size and the encoded visual signals, revealing the predicted information-limiting correlations(12-14). Notably, visual signals were perpendicular to the largest noise mode, which therefore did not limit coding fidelity. The information-limiting noise modes were approximately ten times smaller and concordant with mouse visual acuity(15). Therefore, cortical design principles appear to enhance coding accuracy by restricting around 90% of noise fluctuations to modes that do not limit signalling fidelity, whereas much weaker correlated noise modes inherently bound sensory discrimination.A microscopy system that enables simultaneous recording from hundreds of neurons in the mouse visual cortex reveals that the brain enhances its coding capacity by representing visual inputs in dimensions perpendicular to correlated noise.