Nat:皮层应答选择性源自突触数量的强度 激活的突触总数

邓文龙

皮层应答选择性源自突触数量的强度

选择性似乎源自受不同刺激而激活的突触总数

领研网

2021/02/14
论文
论文标题：Cortical response selectivity derives from strength in numbers of synapses
作者：Benjamin Scholl, Connon I. Thomas, Melissa A. Ryan, Naomi Kamasawa, David Fitzpatrick
期刊：Nature
发表时间：2020/12/16
数字识别码：10.1038/s41586-020-03044-3
摘要：Single neocortical neurons are driven by populations of excitatory inputs, which form the basis of neuronal selectivity to features of sensory input. Excitatory connections are thought to mature during development through activity-dependent Hebbian plasticity1, whereby similarity between presynaptic and postsynaptic activity selectively strengthens some synapses and weakens others2. Evidence in support of this process includes measurements of synaptic ultrastructure and in vitro and in vivo physiology and imaging studies3,4,5,6,7,8. These corroborating lines of evidence lead to the prediction that a small number of strong synaptic inputs drive neuronal selectivity, whereas weak synaptic inputs are less correlated with the somatic output and modulate activity overall6,7. Supporting evidence from cortical circuits, however, has been limited to measurements of neighbouring, connected cell pairs, raising the question of whether this prediction holds for a broad range of synapses converging onto cortical neurons. Here we measure the strengths of functionally characterized excitatory inputs contacting single pyramidal neurons in ferret primary visual cortex (V1) by combining in vivo two-photon synaptic imaging and post hoc electron microscopy. Using electron microscopy reconstruction of individual synapses as a metric of strength, we find no evidence that strong synapses have a predominant role in the selectivity of cortical neuron responses to visual stimuli. Instead, selectivity appears to arise from the total number of synapses activated by different stimuli. Moreover, spatial clustering of co-active inputs appears to be reserved for weaker synapses, enhancing the contribution of weak synapses to somatic responses. Our results challenge the role of Hebbian mechanisms in shaping neuronal selectivity in cortical circuits, and suggest that selectivity reflects the co-activation of large populations of presynaptic neurons with similar properties and a mixture of strengths.

所属学科：
神经科学
（导读 阿金）Hebbian模型认为，神经元之间突触的强度取决于突触前和突触后活动选择相似性。本研究结合光学成像和post hoc电子显微镜，测量了雪貂初级视觉皮层（V1）中连接单个锥体神经元功能特异兴奋性输入的强度，没有证据表明强突触在皮层神经元响应视觉刺激的选择性中发挥主导作用，而选择性似乎源自受不同刺激而激活的突触总数。该结果对Hebbian模型的皮层回路神经元选择性塑造机制提出挑战。

https://www.nature.com/articles/s41586-020-03044-3#Bib1

https://www.linkresearcher.com/t ... 5-ab7d-53a3ec9e126b



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