Impact of local network dynamics on visual cortex function

描述（由申请人提供）：该项目的长期目标是促进我们对皮层网络视觉表征机制的理解。神经元增益，作为刺激输入和细胞输出之间的关系的连续斜率来测量，是神经元对刺激的敏感性的量度，也是单个神经元对网络操作的贡献的定义元素。先前的工作已经确定了网络驱动的突触活动在调节皮层神经元的输入输出增益中的作用。此外，局部网络输入之间的同步可以确定网络活动对神经元增益的影响的大小。先前的研究也表明，神经元增益和群体同步性在介导视觉感知中发挥作用。然而，即使在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知之甚少。 因此，本文提出的工作的主要目标是：1）确定对比度增益控制和网络同步的细胞机制之间的关系; 2）研究群体同步和视觉刺激之间的区分之间的相互作用。为此，第一个目标将集中在许多同时记录皮层神经元在呈现不同性质的刺激。在实验的一个子集中，这些记录将与细胞内记录配对，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个行为任务，其中清醒的，行为动物之间的视觉刺激的不同对比度的歧视。在一系列实验中，这项任务将与初级视觉皮层的群体记录相结合。这些实验的结果有望提供新的见解的时间动态的人口活动和细胞增益控制机制之间的关系。此外，他们将产生一个更好的理解同步皮层网络活动在视觉感知中的作用。 本研究的总体目标是表征在大脑中的视觉处理的早期阶段，在不同的刺激背景下的活动模式，并与这些活动模式的视觉刺激敏感性的个别神经元。我们的持续目标是促进对中枢神经系统在感知处理中的整体功能的理解。

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.