Neuronal basis of stimulus dependent receptive field properties and the role of feedback projections

在具有许多不同视觉皮质区域的哺乳动物中，视觉皮质中的信息处理在很大程度上遵循等级顺序。人们普遍认为，视觉系统中处于最高加工水平的神经元能够凭借其较大的接受视野从外部视觉世界中提取显著的行为特征。然而，在皮质区域之间有大量密集的相互连接，在同一皮质区域内的神经元之间有内部连接。例如，较高处理级别的信息可以通过反馈连接回流到较低处理级别。因此，可以想象，初级视觉皮质中的神经元(在皮质处理的第一阶段)可能具有允许它们整合来自视觉空间中的大区域的大量信息的特性，这是由于存在密集的连接网络。我们希望通过研究单个神经元的详细感受野特性以及当更复杂的视觉刺激呈现在视觉空间时的反应特征来研究初级视觉皮质知觉相关特性的神经元基础。我们还将通过抑制与初级视觉皮质反向连接的高级视觉皮质区域来检查反馈连接对这些神经元特性的影响。希望通过将我们对神经元基本属性的理解与它们在视觉处理中的功能作用联系起来，我们将进一步了解单个视觉皮质区域(本项目中的初级视觉皮质)对视觉感知功能的贡献。

In mammals with a number of distinct visual cortical areas the processing of information in the visual cortex largely follows a hierarchical order. It has been widely assumed that the neurones at the highest processing level in the visual system are capable of extracting behaviorally significant features from the external visual world by virtue of their large receptive fields. However, there are massive and dense inter-connections between the cortical areas and intra-connections between the neurones within the same cortical area. For example the information at the higher processing levels may flow back to the lower ones via the feedback connections. Thus, it is conceivable that the neurones in the primary visual cortex (at the first stage of cortical processing) may posses the properties allowing them to integrate a considerable amount of information from a large area in visual space due to the existence of a dense web of connections. We wish to study the neuronal basis of perceptually related properties in primary visual cortex by examining the detailed receptive field properties of individual neurons and their response characteristics when more complicated visual stimuli are presented in visual space. We will also examine the influence of the feedback connections on the properties of these neurones by silencing the higher-order visual cortical areas which inversely connect to primary visual cortex. It is hoped that by relating our understanding of the basic neuronal properties to their functional roles in visual processing we will obtain further insights concerning the contributions of individual visual cortical areas (primary visual cortex in this project) to the function of visual perception.