NEURAL COMPUTATIONS IN VISUAL CORTEX

本研究包括两种互补的方法，以进一步了解视觉信息是如何在视觉皮层，特别是初级视觉皮层中表征和处理的。目的我将着重于神经放电的颞叶结构。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；（二）视觉信息的时间表征是否有助于后续的视觉处理；(c)时间编码（在单个神经元的尖峰序列中表示视觉信息）与空间编码（跨两个或更多神经元表示视觉信息）的关系。将使用标准的视觉刺激（条形、光栅和复合光栅）。通常的直方图、傅里叶和相互关联分析的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反应嵌入到度量空间中。目的二将着重于由感受野的子区域产生的反应动力学。主要策略将是对m序列技术的适应，以允许分析响应的时间结构。通过比较所有尖峰、突发和“可靠”尖峰产生的感受野图，我们将确定这些时间结构在多大程度上参与信号传递和特征提取。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的整体调制、特定的感受野子区域或在一个扩展的空间区域内的特定相互作用产生的。这些定量实验的目标是在现象学（Aims I）和机械学（Aim II）层面上对视觉皮层如何表征和处理信息的新的定性见解。这将为更好地理解健康和疾病中的大脑功能奠定基础。

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.