Department of Neuroscience, Physiology and Pharmacology, University College London, 21 University Street, London WC1E 6DE, UK.
Nature. 2011 May 5;473(7345):87-91. doi: 10.1038/nature09880. Epub 2011 Apr 10.
Neuronal connectivity is fundamental to information processing in the brain. Therefore, understanding the mechanisms of sensory processing requires uncovering how connection patterns between neurons relate to their function. On a coarse scale, long-range projections can preferentially link cortical regions with similar responses to sensory stimuli. But on the local scale, where dendrites and axons overlap substantially, the functional specificity of connections remains unknown. Here we determine synaptic connectivity between nearby layer 2/3 pyramidal neurons in vitro, the response properties of which were first characterized in mouse visual cortex in vivo. We found that connection probability was related to the similarity of visually driven neuronal activity. Neurons with the same preference for oriented stimuli connected at twice the rate of neurons with orthogonal orientation preferences. Neurons responding similarly to naturalistic stimuli formed connections at much higher rates than those with uncorrelated responses. Bidirectional synaptic connections were found more frequently between neuronal pairs with strongly correlated visual responses. Our results reveal the degree of functional specificity of local synaptic connections in the visual cortex, and point to the existence of fine-scale subnetworks dedicated to processing related sensory information.
神经元连接对于大脑中的信息处理至关重要。因此，要了解感觉处理的机制，就需要揭示神经元之间的连接模式与其功能之间的关系。在粗略的尺度上，长程投射可以优先将对感觉刺激有相似反应的皮质区域连接起来。但在局部尺度上，树突和轴突大量重叠，连接的功能特异性仍然未知。在这里，我们确定了体外附近的第 2/3 层锥体神经元之间的突触连接，这些神经元的反应特性首先在体内的小鼠视觉皮层中进行了表征。我们发现，连接概率与视觉驱动神经元活动的相似性有关。对定向刺激有相同偏好的神经元的连接速度是对正交方向偏好的神经元的两倍。对自然刺激反应相似的神经元的连接速度比无相关性反应的神经元高得多。在视觉反应高度相关的神经元对之间发现了更多的双向突触连接。我们的研究结果揭示了视觉皮层中局部突触连接的功能特异性程度，并指出存在专门用于处理相关感觉信息的精细尺度子网。
