Dynamic coding of image features in primary visual cortex

描述（由申请人提供）：在视觉系统中，从视网膜传递的信息由视觉皮层在多个阶段进行分析和转换，以构建环境的内部表征。长期以来，人们一直认为视觉皮层是一个被动的过滤器，它通过对来自两只眼睛的感官输入的分层处理，创造出视觉场景的静态、空间表现。根据这一观点，神经元对相同刺激的反应变化被认为反映了随机波动或噪音。然而，这种观点在很大程度上忽略了一个事实，即即使闭上眼睛，大脑也远没有安静下来。事实上，一些证据表明，群体活动的波动会导致皮层网络在各种兴奋状态中徘徊。虽然人们已经认识到，正在进行的活动的波动会改变参与刺激处理的皮层网络的状态，但对于皮层状态是否以及如何与传入的刺激相互作用，从而影响视觉表征，以及随后的行为表现，人们知之甚少。本研究将研究初级视觉皮层（V1）神经元持续活动的波动与定向编码（Aim 1）之间的关系，持续活动对神经元群体可靠编码定向信号能力的影响（Aim 2），以及定向识别过程中持续活动、刺激诱发反应和行为表现之间的关系（Aim 3）。我们相信，我们对视觉皮层中状态依赖信息处理的研究有可能促进我们对视觉感知和学习的神经元机制的理解，同时有助于开发可长期植入的人类皮层假体来帮助视障人士。

DESCRIPTION (provided by applicant): In the visual system, the information transmitted from the retina is analyzed and transformed by the visual cortex at multiple stages to construct an internal representation of the environment. It has long been suggested that the visual cortex is a passive filter that creates a static, spatial, representation of a visual scene via a hierarchical processing of sensory inputs from the two eyes. According to this view, variations in neuronal responses to identical stimuli were believed to reflect stochastic fluctuations, or noise. However, this view largely ignores the fact that, even when the eyes are closed, the brain is far from being silent. Indeed, several lines of evidence indicate that fluctuations in population activity cause cortical networks to wander through various states of excitability. Although it is acknowledged that fluctuations in ongoing activity change the state of cortical networks involved in stimulus processing, little is known about whether and how cortical states interact with incoming stimuli to influence visual representations, and subsequently behavioral performance. This proposal will examine the relationship between fluctuations in the ongoing activity of neurons in primary visual cortex (V1) and orientation coding (Aim 1), the influence of ongoing activity on the ability of populations of neurons to reliably encode orientation signals (Aim 2), and the relationship between ongoing activity, stimulus-evoked response, and behavioral performance during orientation discrimination (Aim 3). We believe that our research on state-dependent information processing in visual cortex has the potential to advance our understanding of the neuronal mechanisms underlying visual perception and learning, and, at the same time, help develop chronically-implantable human cortical prostheses to assist visually impaired people.