Processing of thalamocortical inputs by intracortical circuits

摘要 大脑皮层细胞对感觉刺激的反应反映了前馈之间的相互作用。 丘脑皮质输入和正在进行的皮质活动，这可能会受到行为状态的强烈影响。直到 最近，将丘脑皮质和皮质内通路分开是一项具有挑战性的实验。 以及它们对感官反应的独特贡献。我们建议将细胞内记录与 皮层活动的光遗传沉默以检查丘脑皮质(TC)和皮质内(IC)输入 结合起来产生皮质感官反应的三个特征：1)感官上的试验对试验的可变性 响应，2)皮层细胞之间的噪声相关性，以及3)响应变异性的状态依赖调制 和收获。为了解决这些问题，我们将在细胞内记录视觉皮质第四层(L4)神经元 并比较有无大脑皮层光遗传沉默时感觉诱发的突触输入到这些细胞 活动。有人认为，注意和唤醒的调节是通过抑制噪声来调节的 相关性。拟议的实验将确定大脑皮层神经元及其交叉的可变性有多大 相关性继承自丘脑皮质的输入，以及这种可变性和相关的尖峰是否 被皮质处理和行为状态放大或减弱。

Summary The response of cortical cells to sensory stimulation reflects the interactions between feedforward thalamocortical input and ongoing cortical activity which can be strongly affected by behavioral states. Until recently, it has been experimentally challenging to tease apart the thalamocortical and intra-cortical pathways and their unique contributions to the sensory response. We propose to use intracellular recording together with optogenetic silencing of cortical activity to examine how thalamocortical (TC) and intracortical (IC) inputs combine to produce three hallmarks of the cortical sensory response: 1) trial-to-trial variability in the sensory response, 2) noise correlations between cortical cells, and 3) state-dependent modulation of response variability and gain. To address these questions, we will record intracellularly from layer 4 (L4) neurons of visual cortex and compare the sensory-evoked synaptic input to these cells with and without optogenetic silencing of cortical activity. It has been suggested that modulation by attention and arousal are mediated by suppression of noise correlation. The proposed experiments will determine how much variability of cortical neurons and their cross correlation are inherited from thalamocortical inputs, and whether that variability and correlated spiking are amplified or diminished by cortical processing and by behavioral state.