Processing of thalamocortical inputs by intracortical circuits

总结 皮层细胞对感觉刺激的反应反映了前馈神经元之间的相互作用。 丘脑皮层输入和持续的皮层活动，这可能受到行为状态的强烈影响。直到 最近，在实验上很难区分丘脑皮层和皮层内通路 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 皮质活动的光遗传学沉默，以检查丘脑皮质（TC）和皮质内（IC）输入 联合收割机产生皮质感觉反应的三个标志：1）感觉反应中的试验到试验的可变性， 反应，2）皮层细胞之间的噪声相关性，以及3）反应变异性的状态依赖性调制 和增益。为了解决这些问题，我们将在细胞内记录来自视觉皮层的第4层（L4）神经元 并比较这些细胞的感觉诱发的突触输入， 活动有人认为，注意和唤醒的调制是通过抑制噪声来介导的 相关性拟议的实验将确定皮层神经元及其交叉的变异性有多大， 相关性是从丘脑皮层输入中遗传而来的，以及这种变异性和相关的尖峰信号是否 被大脑皮层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.