Photoreceptor Signaling in the Early Visual System

早期视觉系统中的感光信号传导

• 批准号: 8557334
• 负责人: LAWRENCE C SINCICH
• 金额: $ 36.19万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-08-01 至 2018-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8557334
• 关键词: Animal Experimentation; Animal Experiments; Area; Axon; Brain; Code; Color; Color Perception; Color Visions; Effectiveness; Eye; Foundations; Future; Genetic Research; Goals; Grant; Hand; Histologic; Histology; Human; Image; Individual; Inherited; Lasers; Lateral Geniculate Body; Lead; Learning; Left; Life; Light; Location; Macaca; Mammals; Maps; Measures; Microscope; Motion; Mus; Neurons; Ophthalmologist; Ophthalmoscopes; Optics; Output; Pathway interactions; Photoreceptors; Physiological; Physiology; Population; Primates; Problem Solving; Process; Property; Psychophysics; Research; Research Personnel; Retina; Retinal; Retinal Cone; Retinal Diseases; Retinal Ganglion Cells; Scanning; Scheme; Scientist; Sensory; Signal Transduction; Specificity; Staging; Stimulus; Structure; Study Subject; Synapses; Techniques; Testing; Thalamic structure; Time; Tissues; Training; Uncertainty; V1 neuron; Vision; Visual; Visual Cortex; Visual system structure; Weight; Work; adaptive optics; area striata; base; ciliopathy; color processing; computerized data processing; cytochrome c oxidase; design; fovea centralis; ganglion cell; gene therapy; improved; in vivo; instrument; interest; nonhuman primate; public health relevance; receptive field; relating to nervous system; research study; response; retinal stimulation; spatiotemporal

DESCRIPTION (provided by applicant): To understand how we perceive color, it is necessary to learn how our retina creates visual signals from the incoming flux of light. It is known that 3 types of cone photoreceptors are the starting point for any color signals. The cone responses to light are passed to retinal ganglion cells, and their axons leave the eye to provide input to the thalamus, which in turn sends signals to primary visual cortex (V1). Currently, there are two persistent controversies over the chromatic structure of the receptive fields of neurons along this pathway. One controversy concerns the midget class of retinal ganglion cells near the fovea. It is uncertain if these ganglion cells receive input from only single cone types, or from mixed cone types, in their receptive field centers. The two options lead to different color coding schemes at this stage of the visual system, and thus constrain how color is processed at later stages. Because the midget ganglion cells comprise about 80% of the output from the retina, it is crucial to work out their true signaling properties. The second controversy centers on color signaling in V1. Here, it has also been unclear how sensitive are V1 neurons to cone-specific stimuli, and the difficulty has been, in part, inherited from problems associated with uncertainties in the retinal input. The main impediments to solving these problems have been the inability to identify and stimulate individual cones in the retina in vivo. The goal of this proposal is to employ a newly developed retinal microscope that overcomes these hurdles. The instrument can image the cones in a living eye, and can stimulate single cones selectively and repeatably with colored lights. We first propose to verify that cones can be mapped by their spectral sensitivity in humans, using psychophysical techniques. Using the stimulation parameters that allow cone identities to be obtained, we next propose to map physiologically the cone fields that provide input to single neurons in the visual thalamus of a trichromatic primate. With cone-sized stimulation, thalamic neurons receive input essentially from single retinal ganglion cells; thus we will learn whether ganglion cell receptive field centers are composed of pure or mixed cone types. We will focus on foveal thalamic neurons that receive input from the midget retinal ganglion cell class. Finally, we propose to map the cone fields of V1 neurons, to determine the strength of their cone-specific input. We will confirm histologically the location of these neurons in visual cortex, to learn where they are situated within the known anatomical circuits of V1. Our results will afford the first direct mapping of cone fields in vivo, and improve our understanding of how photoreceptor signals are processed by neurons subserving foveal vision.

描述(申请人提供)：为了了解我们如何感知颜色，有必要了解我们的视网膜是如何从传入的光通量中产生视觉信号的。众所周知，三种类型的视锥感光细胞是任何颜色信号的起点。视锥对光的反应被传递到视网膜神经节细胞，它们的轴突离开眼睛，向丘脑提供输入，丘脑继而向初级视觉皮质(V1)发送信号。目前，关于神经元感受野的染色结构有两个持续的争议。 路径。其中一个争议与黄斑中心凹附近的小型视网膜神经节细胞有关。目前尚不清楚这些神经节细胞在其感受野中心是只接受单一视锥类型的信息，还是接受混合视锥类型的信息。这两个选项在视觉系统的这个阶段导致不同的颜色编码方案，从而限制了在以后的阶段如何处理颜色。由于侏儒神经节细胞约占视网膜输出的80%，因此弄清它们的真实信号特性至关重要。第二个争议集中在V1中的颜色信号上。在这里，也不清楚V1神经元对视锥细胞特异性刺激有多敏感，困难在一定程度上是由与视网膜输入不确定相关的问题遗传的。解决这些问题的主要障碍是无法在体内识别和刺激视网膜中的单个视锥细胞。这项提议的目标是使用一种新开发的视网膜显微镜来克服这些障碍。该仪器可以在活人的眼睛中对视锥细胞进行成像，并可以用彩色灯光选择性和重复地刺激单个视锥细胞。我们首先提出使用心理物理技术来验证锥体可以通过它们在人类身上的光谱敏感度进行映射。使用可以获得视锥细胞特性的刺激参数，我们下一步建议从生理上映射为三色灵长类动物的视觉丘脑中的单个神经元提供输入的视锥细胞区域。在锥体大小的刺激下，丘脑神经元基本上接受来自单个视网膜神经节细胞的输入；因此，我们 将了解神经节细胞感受野中心是由纯锥体类型还是混合锥体类型组成。我们将重点研究从侏儒视网膜神经节细胞类接收输入的丘脑中心凹神经元。最后，我们建议映射V1神经元的锥场，以确定其锥体特定输入的强度。我们将在组织学上确认这些神经元的位置 在视觉皮质，以了解它们在已知的V1解剖回路中的位置。我们的结果将提供第一次在活体内直接绘制锥体场的地图，并提高我们对服务于中心凹视觉的神经元如何处理光感受器信号的理解。