Impact of local network dynamics on visual cortex function

描述(由申请人提供)：本项目的长期目标是帮助我们理解大脑皮层网络视觉表征的机制。神经元增益衡量的是刺激输入和细胞输出之间关系的连续斜率，是神经元对刺激的敏感性的衡量标准，也是单个神经元对网络操作贡献的决定性因素。以前的工作已经确定了网络驱动的突触活动在调节皮质神经元的输入-输出增益中所起的作用。此外，局部网络输入之间的同步性可能决定网络活动对神经元增益的影响的大小。以前的研究也表明，神经元获得和群体同步性都在调节视觉知觉中发挥作用。然而，即使在大脑皮层视觉处理的最早阶段，单个神经元和它们所嵌入的网络之间的关系也鲜为人知。 因此，这项工作的主要目标是1)确定对比度增益控制的细胞机制和网络同步之间的关系；2)研究群体同步和视觉刺激之间的辨别之间的交互作用。为此，第一个目标将集中在呈现具有不同性质的刺激期间的许多皮层神经元的同时记录。在一组实验中，这些录音将与细胞内录音配对，以测试网络活动对突触后细胞的影响。第二个目标将使用一项行为任务，在这项任务中，清醒的、行为正常的动物区分不同对比度的视觉刺激。在一系列实验中，这项任务将与初级视觉皮质的群体记录相结合。这些实验的结果有望为研究种群活动的时间动态和细胞增益控制机制之间的关系提供新的见解。此外，他们还将更好地理解同步大脑皮层网络活动在视觉感知中的作用。 这项研究的总体目标是描述大脑视觉处理早期阶段的活动模式，以响应不同的刺激环境，并将这些活动模式与单个神经元的视觉刺激敏感性联系起来。我们的持续目标是促进对中枢神经系统在知觉处理中的全球功能的理解。

DESCRIPTION (provided by applicant): The long-term objective of this project is to contribute to our understanding of the mechanisms of visual representation by cortical networks. Neuronal gain, measured as the continuous slope of the relationship between stimulus input and cellular output, is a measure of neuronal sensitivity to the stimulus and a defining element of the contribution of single neurons to network operations. Previous work has identified a role for network-driven synaptic activity in modulating the input-output gain of cortical neurons. In addition, synchrony between local network inputs may determine the magnitude of the impact of network activity on neuronal gain. Previous studies have also suggested that both neuronal gain and population synchrony play roles in mediating visual perception. However, even at the earliest stages of cortical visual processing, the relationship between individual neurons and the network in which they are embedded is poorly understood. The main goals of the work proposed here are therefore 1) to determine the relationship between cellular mechanisms of contrast gain control and network synchrony and 2) to examine the interaction between population synchrony and discrimination between visual stimuli. To that end, the first Aim will focus on many simultaneous recordings of cortical neurons during presentation of stimuli with varying properties. In a subset of experiments, these recordings will be paired with intracellular recordings to test the impact of network activity on postsynaptic cells. The second Aim will use a behavioral task in which awake, behaving animals discriminate between visual stimuli of varying contrast. In one series of experiments, this task will be combined with population recordings from primary visual cortex. The results of these experiments are expected to provide novel insights into the relationship between the temporal dynamics of population activity and cellular mechanisms of gain control. In addition, they will generate a better understanding of the role of synchronous cortical network activity in visual perception. The overall objective of this research is to characterize the patterns of activity at the early stages of visual processing in the brain in response to differing stimulus contexts and relate those patterns of activity to the visual stimulus sensitivity of individual neurons. Our continuing goal is to advance understanding of global functions of the central nervous system in perceptual processing.