Howard Hughes Medical Institute, Center for Neural Circuits and Behavior, Neurobiology Section and Department of Neuroscience, University of California San Diego, La Jolla, California 92093-0634, USA.
Nature. 2012 Feb 22;483(7387):47-52. doi: 10.1038/nature10835.
After entering the cerebral cortex, sensory information spreads through six different horizontal neuronal layers that are interconnected by vertical axonal projections. It is believed that through these projections layers can influence each other's response to sensory stimuli, but the specific role that each layer has in cortical processing is still poorly understood. Here we show that layer six in the primary visual cortex of the mouse has a crucial role in controlling the gain of visually evoked activity in neurons of the upper layers without changing their tuning to orientation. This gain modulation results from the coordinated action of layer six intracortical projections to superficial layers and deep projections to the thalamus, with a substantial role of the intracortical circuit. This study establishes layer six as a major mediator of cortical gain modulation and suggests that it could be a node through which convergent inputs from several brain areas can regulate the earliest steps of cortical visual processing.
进入大脑皮层后，感觉信息通过六个不同的水平神经元层传播，这些神经元层通过垂直的轴突投射相互连接。人们认为，通过这些投射，各个层可以相互影响对感觉刺激的反应，但每个层在皮层处理中所起的具体作用仍不清楚。在这里，我们表明，在小鼠的初级视觉皮层中，第六层在控制上层层神经元对视觉刺激活动的增益方面起着关键作用，而不改变它们对方向的调谐。这种增益调制是由第六层皮层内投射到浅层和深部投射到丘脑的协同作用引起的，其中皮层内回路起着重要作用。这项研究确立了第六层作为皮层增益调制的主要介导者，并表明它可能是一个节点，来自几个脑区的会聚输入可以通过它来调节皮层视觉处理的最早步骤。
