Gómez-Laberge Camille, Smolyanskaya Alexandra, Nassi Jonathan J, Kreiman Gabriel, Born Richard T
Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, Massachusetts 02115, USA.
Department of Ophthalmology, Boston Children's Hospital and Harvard Medical School, 300 Longwood Avenue, Boston, Massachusetts 02115, USA.
Neuron. 2016 Aug 3;91(3):540-547. doi: 10.1016/j.neuron.2016.06.028. Epub 2016 Jul 14.
Neurons in the cerebral cortex respond inconsistently to a repeated sensory stimulus, yet they underlie our stable sensory experiences. Although the nature of this variability is unknown, its ubiquity has encouraged the general view that each cell produces random spike patterns that noisily represent its response rate. In contrast, here we show that reversibly inactivating distant sources of either bottom-up or top-down input to cortical visual areas in the alert primate reduces both the spike train irregularity and the trial-to-trial variability of single neurons. A simple model in which a fraction of the pre-synaptic input is silenced can reproduce this reduction in variability, provided that there exist temporal correlations primarily within, but not between, excitatory and inhibitory input pools. A large component of the variability of cortical neurons may therefore arise from synchronous input produced by signals arriving from multiple sources.
大脑皮层中的神经元对重复的感觉刺激反应不一致，但它们却是我们稳定的感觉体验的基础。尽管这种变异性的本质尚不清楚，但其普遍性促使人们形成了一种普遍观点，即每个细胞都会产生随机的脉冲模式，这些模式以嘈杂的方式代表其反应率。相比之下，我们在此表明，在警觉的灵长类动物中，可逆地灭活皮层视觉区域自下而上或自上而下输入的远距离源，会降低单个神经元的脉冲序列不规则性和试验间变异性。一个简单的模型，即一部分突触前输入被沉默，就可以重现这种变异性的降低，前提是兴奋性和抑制性输入池内主要存在时间相关性，而不是它们之间。因此，皮层神经元变异性的很大一部分可能源于来自多个源的信号产生的同步输入。
