NEURAL COMPUTATIONS IN VISUAL CORTEX

这项拟议的研究由两个互补的方法组成，以进一步了解视觉信息在视觉皮质，特别是初级视觉皮质中是如何呈现和处理的。目的我将重点介绍神经放电的时间结构。这些目标将决定(A)神经放电的时间模式在多大程度上有助于特定类型的视觉信息的表征，包括基本的空间特征和颜色；(B)视觉信息的时间表征是否可以促进随后的视觉处理；以及(C)时间编码(单个神经元的棘波序列内的视觉信息表征)与空间编码(跨两个或多个神经元的视觉信息表征)的关系。将使用标准视觉刺激(条形、格栅和复合格栅)。通常的直方图、傅立叶和互相关分析方法将被本实验室最近开发的一系列新方法所增强，这些方法基于将神经响应嵌入到度量空间中。AIM II将专注于通过感受野的亚区产生反应动力学。主要战略将是对m序列技术进行调整，以便能够分析响应的时间结构。通过比较所有脉冲、突发脉冲和“可靠”脉冲产生的感受野映射，我们将确定这些时间结构在多大程度上参与特征的信号传递和提取。M序列分析将显示这些时间结构在多大程度上是由响应特性、特定感受场亚区或扩展空间区域上的特定相互作用的整体调制引起的。这些定量实验的目标是对视觉皮质如何在现象学(目标I)和机械学(目标II)水平上表示和处理信息进行新的定性洞察。这将为更好地了解大脑在健康和疾病中的功能奠定基础。

The proposed research consists of two complementary approaches to further the understanding of how visual information is represented and processed in visual cortex, particularly primary visual cortex. Aims I will focus on the temporal structure of the neural discharge. These aims will determine (a) the extent to which the temporal pattern of a neural discharge contributes to the representation of particular kinds of visual information, including elementary spatial features and color; (b) whether the temporal representation of visual information can facilitate subsequent visual processing; and (c) the relationship of temporal coding (representation of visual information within the spike train of a single neuron) to spatial coding (representation of visual information across two or more neurons). Standard visual stimuli (bars, gratings, and compound gratings) will be used. The usual analytical approaches of histogram, Fourier, and cross-correlation analysis will be augmented by a family of new methods recently developed in this laboratory, based on the embedding of neural responses into a metric space. Aim II will focus on the generation of response dynamics by subregions of the receptive field. The main strategy will be an adaptation of the m-sequence technique to allow analysis of the temporal structure of the response. Through comparison of receptive field maps generated by all spikes, by bursts, and by "reliable" spikes, we will determine to what extent these temporal structures participate in the signaling and extraction of features. The m-sequence analysis will show the extent to which these temporal structures arise from an overall modulation of response properties, specific receptive field subregions, or specific interactions over an extended region of space. The goals of these quantitative experiments are new qualitative insights into how the visual cortex represents and processes information, on phenomenological (Aims I) and mechanistic (Aim II) levels. This will serve as a basis for a better understanding of brain function in health and disease.