Tuning diversity in the functional microarchitecture of visual cortex

描述(申请人提供)：在大型哺乳动物的初级视觉皮质(V1)，固有信号光学成像显示了连续的地形图的调谐偏好。正如高效神经代码所预期的那样，不同刺激参数的映射往往会重叠，从而使它们的轮廓彼此垂直。然而，最终的编码效率取决于调谐偏好和调谐形状在精细空间尺度上的组织，这需要具有微观分辨率的功能测量。在这里，我们建议在猕猴VI中使用双光子成像来表征所谓的超柱内的调谐多样性，并测量其对整个种群代码的理论影响。利用双光子成像，我们可以逐细胞地测量数百微米宽的皮质斑块上多个刺激属性的调谐曲线。目标1是研究每个单元的调谐形状与调谐曲线的相邻总体之间的关系。这些实验和分析将帮助我们更好地理解大脑皮层如何执行影响单个神经元调谐特性的局部计算。在目标2中，我们将测试调优多样性对超列中信息内容的影响。这些分析旨在寻找将神经元嵌入连续功能图以将有关视觉场景的信息传输到下游皮质区域的可能好处。在目标3中，我们将研究一个相关的问题。我们假设皮质超柱在其对刺激属性的覆盖方面并不完美，并且这被调谐带宽的变化所抵消。总体而言，本提案中的实验和分析旨在使用一种强大的新技术来解决感觉系统神经科学中的基本问题。与公共健康相关：我们希望获得关于大脑皮层回路如何整合感觉输入的知识，以便信息能够忠实地传递到更高水平的区域，以创造正常行为。许多神经疾病，如自闭症、注意力缺陷障碍(ADD)、癫痫和精神分裂症，人们知之甚少。有关正常皮质功能的知识，如基本的连接规则和皮质功能的组织，是我们理解异常皮质活动的基础。

DESCRIPTION (provided by applicant): In primary visual cortex (V1) of large mammals, intrinsic signal optical imaging has demonstrated continuous topographic maps of tuning preference. As expected for an efficient neural code, the maps of different stimulus parameters tend to overlap such that their contours run perpendicular to each other. However, the ultimate coding efficiency is dependent on the organization of both tuning preference and tuning shape at a fine spatial scale, which requires functional measurements with microscopic resolution. Here, we propose the use of two-photon imaging in macaque VI to characterize tuning diversity within the so-called hypercolumn and to measure its theoretical consequences on the overall population code. With two-photon imaging, we can measure tuning curves of multiple stimulus properties on a cell-by-cell basis across a patch of cortex that is hundreds of microns wide. Aim 1 is to investigate relationships between each cell's tuning shape and the neighboring population of tuning curves. The experiments and analyses will help us to better understand how the cortex performs local computations that affect the tuning properties of individual neurons. In Aim 2, we will test the impact of tuning diversity on information content within the hypercolumn. The analyses are directed toward finding possible benefits of having neurons embedded in continuous functional maps for transmitting information about the visual scene to downstream cortical areas. In Aim 3, we will examine a related issue. We hypothesize that the cortical hypercolumn is not perfect in its coverage of stimulus properties and that this is counterbalanced by changes in tuning bandwidth. Overall, the experiments and analyses in this proposal are designed to address fundamental questions in sensory systems neuroscience using a powerful new technique. PUBLIC HEALTH RELEVANCE: We expect to acquire knowledge on how cortical circuits integrate sensory input so that the information can be faithfully passed on to higher level areas to create normal behavior. Many neurological disorders such as autism, attention deficit disorder (ADD), epilepsy, and schizophrenia, are poorly understood. Knowledge about normal cortical function such as basic wiring rules and the organization of functionality in the cortex is fundamental to our understanding of abnormal cortical activity.