MECHANISMS OF VISUAL CONTEXT EFFECTS IN VISUAL CORTEX

位于经典感受野(可诱发反应的视野区域)之外位置的视觉刺激可以对视觉皮质神经元反应的选择性和大小产生深远影响，即使这些刺激本身并不能引起反应。通常认为，内在的解剖学联系是这些调节作用的基础。了解这种调节效应是如何塑造皮质神经元反应的，对于理解皮质组织在决定皮质功能中的作用，以及大脑的视觉区域如何处理复杂的现实世界场景非常重要。在这项研究中，我们将阐明视觉刺激的空间分布如何塑造视觉皮质中的神经元反应，并阐明连接皮质上不同点(因此是不同的空间位置)的解剖学基础。因此，这将允许直接测试局部皮质连接是否确实构成了这些调制环绕效应的基础。1)在成年猕猴和雪貂的电生理和神经解剖学实验中，我们将测试来自经典感受野之外的反应抑制或增强的空间范围和地形图是否可以用初级视觉皮质(V1)和V2内局部水平或皮质反馈联系的分布来解释。2)在成年猴和雪貂的电生理研究中，我们将探索V1和V2中经典感受野以外的反应调制的刺激特异性。我们将重点放在V1作为通往其他皮质视觉区域的门户，但也将研究V2，以阐明这些调制效应的属性和功能对所有皮质视觉区域是多么普遍。3)在雪貂的发育研究中，我们将在大范围的出生后年龄范围内，系统地比较调制环境效应的发展与经典感受野中反应的发展，以及V1中内在和外在联系的细化。这将使我们能够将调制效应的发展精细化与经典的感受野特性进行比较，并进一步测试内在联系是否存在于环绕调制之下。比较不同解剖回路的选择性和空间范围的细节，以及来自生理学研究的类似细节，将提供至关重要的信息，以了解哪些解剖回路构成特定功能的基础，以及神经元功能和连接如何支撑视觉表现。这是理解大脑皮层如何工作的一个基本问题，无论是在视觉上还是在高级认知功能中。

Visual stimuli at locations beyond the classical receptive field (the area of the visual field from which responses can be evoked) can have profound effects on the selectivity and magnitude of neuronal responses in the visual cortex, even when these stimuli do not themselves evoke responses. It is generally assumed that intrinsic anatomical connections underlie these modulatory effects. Understanding how cortical neuron responses are shaped by such modulatory effects is important for understanding the role of cortical organization in determining cortical function, and in how the visual areas of the brain process complex real- world scenes. In this study we will clarify how neuronal responses in visual cortex are shaped by the spatial distribution of visual stimuli, and we will elucidate the anatomical substrates that link different points on the cortex (and therefore different spatial locations). This will therefore permit a direct test of whether local cortical connections do in fact underlie these modulatory surround effects. 1) In electrophysiological and neuroanatomical experiments in adult monkeys and ferrets, we will test whether the spatial extent and topography of response suppression or enhancement from beyond the classical receptive field can be accounted for by the distribution of local horizontal or cortical feedback connections within primary visual cortex (V1) and V2. 2) In electrophysiological studies in adult monkeys and ferrets, we will explore the stimulus specificity of response modulation from beyond the classical receptive field in V1 and V2. We will focus on V1 as the gateway to other cortical visual areas, but will also examine V2 to illuminate how general the properties and function of these modulatory effects are to all cortical visual areas. 3) In developmental studies in ferrets, we will systematically compare, across a large range of postnatal ages, the development of the modulatory surround effects to that of the responses in the classical receptive field, and to the refinement of intrinsic and extrinsic connections in V1. This will allow us to compare the developmental refinement of the modulatory effects to classical receptive field properties, and to further test whether intrinsic connections can underlie surround modulation. Comparison of details of the selectivity and spatial extent of different anatomical circuits with similar details from physiological investigations will provide information critical to an understanding of which anatomical circuits underlie particular functions, and in how neuronal function and connectivity underlie visual performance. This is a fundamental question in understanding how the cerebral cortex works, both in vision and in higher cognitive function.