FUNCTIONAL ORGANIZATION OF THE VISUAL SYSTEM

大脑控制视网膜中的视觉处理是主要的 项目的重点。 鲎脑中的生物钟 产生传出视神经活动， 侧眼的结构和功能。 这一发现开启了 新的研究领域。 它提供了第一个证据， 光感受器功能和代谢的直接传出控制。 具体目标是调查： 1.视网膜功能传出控制 2.传出神经递质 3.传出作用的细胞机制 4.光感受器代谢的昼夜调节 5.视觉系统的昼夜结构 6.视网膜昼夜节律在行为中的作用 一个主要的努力将是确定传出 神经递质，并确定其作用机制， 视网膜功能 章鱼胺就是其中之一。 它能激活腺苷酸 光感受器中的环化酶，产生第二种递质cAMP。 神经肽（大约2000道尔顿）似乎是另一种， 而最近的研究则指向了一种循环的光适应激素。 我们将试图了解这些发射器如何产生多个 视网膜结构和功能的昼夜变化。 我们将使用解剖学，生理学，神经化学，核磁共振技术， 和行为。 我们的生理学技术可以提供长期的视网膜电图 (less 5个月以上），视神经（约5天），和 光感受器（约50小时）记录从横向 眼睛在原地。 它们还提供对传出神经的精确控制 输入到视网膜。 我们已经开发出了记录 来自分离的大脑的时钟活动（大约2天）， 正在研究从分离的光感受器中记录的技术。 我们所知的其他动物模型都不能提供所有这些实验性的 优势 它们非常适合研究传出神经 控制视网膜功能，并建立Limulus作为适当的 模型为这项研究。 该项目的主要宗旨是， 对鲎视觉系统的研究将产生 理解视觉处理的基本机制。 过去 对鲎的研究标志着视觉研究的一个里程碑。 的 拟议的研究可能同样富有成效。 他们应该 对我们的长期目标理解有重大贡献 视觉系统的功能组织。

Control by the brain of visual processing in the retina is the main focus of the project. A circadian clock in the Limulus brain generates efferent optic nerve activity that modulates retinal structure and function of the lateral eye. This discovery opens up new areas of research. It provides the first evidence for the direct efferent control of photoreceptor function and metabolism. Specific aims are to investigate: 1. efferent control of retinal function 2. efferent neurotransmitter(s) 3. cellular mechanisms of efferent action 4. circadian modulation of photoreceptor metabolism 5. circadian organization of the visual system 6. role of retinal circadian rhythms in behavior A major effort will be made to identify the efferent neurotransmitter(s) and determine their mechanisms of action on retinal function. Octopamine is one. It activates adenylate cyclase in photoreceptors producing a second transmitter, cAMP. A neuropeptide (approximately 2000 daltons) appears to be another, and recent work points to a circulating light-adapting hormone. We will try to understand how these transmitters produce multiple circadian changes in the structure and function of the retina. We will use techniques of anatomy, physiology, neurochemistry, NMR, and behavior. Our physiological techniques provide long-term ERG (less than 5 months), optic nerve (approximately 5 days), and photoreceptor (approximately 50 hours) recordings from the lateral eye in situ. They also provide precise control of the efferent input to the retina. We have developed techniques to record the clock's activity from isolated brains (approximately 2 days) and are working on techniques to record from isolated photoreceptors. No other animal model we know offers all these experimental advantages. They are ideally suited for investigating the efferent control of retinal function and establish Limulus as an appropriate model for this research. The primary tenet of the project is that further comprehensive studies of the Limulus visual system will yield fundamental understandings of basic mechanisms of visual processing. Past studies with Limulus mark a milestone in vision research. The proposed studies may prove equally productive. They should contribute significantly toward our long-term goal understanding the functional organization of the visual system.