Neural Mechanisms of Visual Perception

描述(由申请人提供)：视觉的神经生物学已成为理解高级认知过程(如决策)的首要模型。事实上，现在对神经机制的了解很多，这些神经机制是在对模糊视觉刺激的两种不同解释之间做出简单决定的速度和准确性的基础。例如，在一项动作辨别任务中，猴子顶叶皮质的神经元通过整合视皮层神经元的反应，作为时间的函数，为替代方案积累证据。当证据积累达到标准水平时，决策过程被认为是终止的。尽管这些神经元可以洞察大脑的计算，但尚不清楚它们是否真的促使大脑做出决定。也不知道他们是如何管理更复杂的决策的。这项拟议的研究测试了顶叶皮质神经元在决策中起因果作用的假设，并研究了这些神经元在更复杂的决策中的作用，这些决策更像是人类依赖于执行认知任务的决策。这些实验将恒河猴的神经记录和刺激与猴子和人类的行为测量结合在一起。计划了三个具体目标。1)微刺激外侧顶内区(LIP)将阐明LIP神经元活动的变化如何影响对模棱两可的运动刺激的知觉决定，以及这些神经元是否导致大脑做出决定。2)嘴唇区域的神经记录以及对猴子和人类的行为测试将揭示当有两个以上的选择可供选择时，知觉决定背后的机制。3)嘴唇区域的神经记录以及对猴子和人的行为测试将揭示大脑如何结合来自多个来源的信息，以在概率分类任务中做出决定。了解决策背后的神经机制将有助于阐明导致认知及其障碍的神经科学原理。拟议的实验利用了视觉神经科学知识的坚实基础，有助于理解认知推理。这样的理解有望提供在面对神经疾病时促进感觉和智力功能恢复的手段。

DESCRIPTION (provided by applicant): The neurobiology of vision has emerged as the premier model for understanding higher cognitive processes such as decision-making. Indeed much is now understood about the neural mechanisms that underlie both the speed and accuracy of simple decisions between two alternative interpretations of an ambiguous visual stimulus. In a motion discrimination task, for example, neurons in the parietal cortex of the monkey accumulate evidence for the alternatives by integrating, as a function of time, the responses of neurons in the visual cortex. The decision process is thought to terminate when the accumulation of evidence reaches a criterion level. Although these neurons lend insight into the brain's computations, it is not known whether they actually cause the brain to commit to a decision. Nor is it known how they govern more complex decisions. The proposed research tests the hypothesis that neurons in parietal cortex play a causal role in decisions, and it examines the role of these neurons in more complicated decisions that are more like the ones humans rely on to perform cognitive tasks. The experiments combine neural recording and stimulation in rhesus monkeys with behavioral measurements in both monkeys and humans. Three specific aims are planned. 1) Microstimulation of the lateral intraparietal area (LIP) will elucidate how changes in the activity of LIP neurons affect perceptual decisions about an ambiguous motion stimulus and whether these neurons cause the brain to commit to a decision. 2) Neural recordings in area LIP along with behavioral testing in monkey and man will reveal the mechanism underlying perceptual decisions when there are more than two alternatives to choose among. 3) Neural recordings in area LIP along with behavioral testing in monkey and man will reveal how the brain combines information from several sources to reach a decision in a probabilistic classification task. Understanding the neural mechanisms that underlie decisions will help to elucidate the principles of neuroscience that give rise to cognition and its disorders. The proposed experiments leverage a solid foundation of knowledge of visual neuroscience toward an understanding of cognitive reasoning. Such understanding promises to provide the means to promote recovery of both sensory and intellectual function in the face of neurological disease.