Dynamic coding of image features in primary visual cortex

描述(申请人提供)：在视觉系统中，从视网膜传输的信息由视觉皮质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，视觉皮质是一种被动过滤器，它通过对两只眼睛的感觉输入进行分级处理，创建一种静态的、空间的视觉场景表征。根据这一观点，神经元对相同刺激反应的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，大脑也远不是沉默的。事实上，有几条证据表明，人口活动的波动导致大脑皮层网络在不同的兴奋性状态中游荡。虽然人们已经认识到，持续活动的波动会改变参与刺激加工的皮层网络的状态，但关于皮层状态是否以及如何与传入刺激相互作用来影响视觉表征以及随后的行为表现，我们知之甚少。这项建议将研究初级视觉皮质神经元正在进行的活动(V1)和定向编码(目标1)之间的波动之间的关系，正在进行的活动对神经元群体可靠编码定向信号的能力的影响(目标2)，以及正在进行的活动、刺激诱发反应和定向辨别过程中的行为表现之间的关系(目标3)。我们相信，我们对视觉皮质状态相关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机制的理解，同时有助于开发长期植入的人类皮质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.