Excitation and Inhibition in Neural Circuits of the Visual Cortex

项目总结 初级视觉皮层(V1)的神经回路对于产生对外部世界的感知至关重要。在……里面 V1，大多数神经元都表现出强大的调制能力，这一过程被称为 “环绕调制”。重要的是，环绕调制的大小和符号取决于方向 中心和环绕的对比度-导致了灵活的环绕调制有助于 场景分割、显著度检测、轮廓融合和图形/背景分离。具体的 V1中解释环绕调制的特征依赖的神经电路在很大程度上是未知的。通过 在清醒状态下结合细胞内外电生理学、双光子成像和光遗传学 小鼠，我们的目标是揭示V1中能够解释V1这些基本特征的抑制电路 计算。具体地说，我们将测试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，为这一特征提供了电路和突触基础 环绕调制的依赖性。我们将成像这两个亚型的视觉反应，然后 在记录细胞外神经活动或突触电流的同时，以光遗传学的方式操纵它们 在细胞内，测试他们的视觉反应和网络影响是否与 环绕调制的取向和对比度相关性。这些实验将提供关键的新技术 深入了解大脑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.