Neural mechanisms that limit the visual sensitivity of primates

这个项目关注的是大脑中的神经细胞如何能够检测和感知视觉世界中的物体。人们认为，视觉通路早期的神经细胞发出信号，表明视野的一小部分有没有光，但这些通路携带的神经元编码的性质仍然知之甚少。我们项目的目的是在对完整的灵长类视觉系统的实验研究中解决这个基本问题。我们将进行两组实验。首先，我们将检验一个假设，即早期视觉系统中的神经细胞只对一小部分视野敏感。我们将确定皮质前神经细胞的信号是否依赖于空间环境。其次，我们利用多个电极同时研究多个神经细胞的信号。我们将确定是否需要许多神经细胞的信号来检测像视野检查中使用的那样的微小视觉刺激。这些实验解决了基本问题，但也适用于人类视觉和视觉功能障碍。良好的敏锐度对于阅读等日常任务至关重要，视觉敏感度缺陷被用来早期发现青光眼和黄斑变性等疾病的神经功能障碍。因此，了解构成视觉感知的神经元的特性可以帮助我们了解正常的视觉表现，以及这种表现在部分视觉中是如何变化的。这有助于开发更好的方法来检测和治疗此类疾病。

This project concerns the way nerve cells in the brain enable the detection and perception of objects in the visual world. It is thought that nerve cells early in the visual pathway signal the presence or absence of light in a small part of the visual field, but the nature of the neuronal code carried by these pathways remains poorly understood. The aim of our project is to address this basic question, in experimental studies of the intact primate visual system. We will conduct two sets of experiments. Firstly, we will test the hypothesis that nerve cells in the early visual system are sensitive to only a small part of the visual field. We will determine whether the signals of pre-cortical nerve cells are dependant on spatial context. Secondly we wll study the signals of several nerve cells simultaneously using multiple electrodes. We will determine if the signals of many nerve cells are required to detect small visual stimuli like those used in perimetry. These experiments address basic questions, but have application to human vision and visual dysfunction. Good acuity is essential for everyday tasks such as reading, and defects in visual sensitivity are used for early detection of neurological dysfunction in diseases such as glaucoma and macular degeneration. Understanding the properties of neurons which underlie visual perception can thus help us to understand normal visual performance, and how this changes in partial sight. This can help develop better methods for detection and treatments for such disorders.