Excitation and Inhibition in Neural Circuits of the Visual Cortex

项目摘要 初级视觉皮层（V1）的神经回路对于产生我们对外部世界的感知至关重要。在 V1，大多数神经元表现出强有力的调制，刺激是在他们的感受野，一个过程称为 “环绕调制”。重要的是，环绕调制的幅度和符号取决于方向 以及中心和环绕的对比度-导致灵活的环绕调制有助于 场景分割、显著性检测、轮廓整合和图形/背景分离。具体 解释环绕调制的特征依赖性的V1神经回路在很大程度上是未知的。通过 结合细胞内和细胞外电生理学、双光子成像和光遗传学， 我们的目标是揭示V1的抑制回路，可以解释V1的这些基本特征 计算具体地说，我们将检验两种类型之间的竞争性抑制相互作用的假设， V1 GABA能中间神经元（“SST”和“VIP”）细胞的神经网络，提供了一个电路和突触基础的特点， 环绕调制的依赖性。我们将对这两种亚型的视觉反应进行成像， 在记录细胞外神经活动或突触电流的同时， 细胞内，以测试他们的视觉反应和网络影响是否与在细胞内的关键作用一致。 环绕调制的方向和对比度依赖性。这些实验将提供关键的新的 深入了解皮层抑制回路如何调节感官知觉的关键方面。

PROJECT SUMMARY Neural circuits of the primary visual cortex (V1) are critical for generating perceptions of our external world. In V1, most neurons exhibit potent modulation by stimuli that are outside their receptive fields, a process termed ‘surround modulation’. Importantly, the magnitude and sign of surround modulation depend on the orientation and contrast of the center and surround – leading to the notion that flexible surround modulation contributes to scene segmentation, salience detection, contour integration, and figure/ground segregation. The specific neural circuits in V1 that explain the feature dependence of surround modulation are largely unknown. By combining intracellular and extracellular electrophysiology, two photon imaging, and optogenetics in awake mice, we aim to reveal the inhibitory circuits in V1 that can account for these fundamental features of V1 computation. Specifically, we will test the hypothesis that a competitive inhibitory interaction between two types of V1 GABAergic interneurons (‘SST’ and ‘VIP’) cells, provides a circuit and synaptic basis for the feature dependence of surround modulation. We will image the visual responses of these two subtypes, then manipulate them optogenetically while recording neural activity extracellularly, or synaptic currents intracellularly, to test whether their visual responses and network impact are consistent with key roles in the orientation and contrast dependence of surround modulation. These experiments will provide critical new insight into how cortical inhibitory circuits mediate key aspects of sensory perception.