International Research Fellowship Program: Quantitative Analysis of Cortical Response Dependence on Network Activity

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。国际研究奖学金项目使美国科学家和工程师能够在国外进行9至24个月的研究。该计划的奖励为联合研究提供了机会，并利用独特或互补的设施、专业知识和国外的实验条件。该奖项将支持Neel T. Dhruv博士与英国伦敦大学学院的Matteo Carandini博士进行为期24个月的研究。大脑中的神经细胞从广泛的网络连接中接收信息。对于一个给定的细胞，这些连接可能来自大脑的遥远部分，也可能来自神经元内部。我们当地的邻居。例如，初级视觉皮层（V1）的神经元接受来自丘脑的前馈输入和来自V1内部的侧向连接。然而，这两种输入在驱动V1反应中的相对影响仍然未知，并且是当前许多争论的主题。在这个项目中，PI将研究前馈连接和横向连接的相对贡献如何塑造V1神经元的反应并促进其变异性。他假设V1可以在两种状态下运作？一种是由前馈连接（“接受场”）主导的。另一种是由皮层连接（连接场）主导的。政权)。此外，他假设主导模式是由许多内在因素决定的，包括细胞类型、层流位置和刺激属性，如对比度。他将在被麻醉的小鼠身上进行实验，将单单元电生理学与光学成像（使用电压敏感染料）相结合。电成像?（多电极阵列）。刺激是在相位、方向和空间频率上变化的随机光栅序列，每个刺激集合在多个对比度水平下呈现。因此，他可以同时测量单个神经元的脉冲序列及其皮质邻近区域的活动，并将两者与视觉刺激的历史联系起来。π吗?他的实验将有助于揭示V1神经元如何对不同的输入进行加权，以及不同细胞类别或不同层状细胞的加权有何不同。此外，这项研究将有助于推动小鼠作为视觉研究的实验模型，从而减少未来对灵长类动物研究的需求。

0853093DhruvThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-four-month research fellowship by Dr. Neel T. Dhruv to work with Dr. Matteo Carandini at University College London, in the UK.Nerve cells in the brain receive information from an extensive network of connections. For a given cell, these connections could originate from distant parts of the brain as well as from within a neuron?s local neighborhood. For example, neurons in primary visual cortex (V1) receive feed-forward inputs from thalamus and lateral connections from within V1. However, the relative influence of these two inputs in driving V1 responses remains unknown and is the subject of much current debate. In this project, the PI will investigate how the relative contributions of feed-forward connections and lateral connections shape the responses and contribute to the variability of neurons in V1. He hypothesizes that V1 can operate in two regimes ? one that is dominated by feed-forward connections (a ?receptive-field? regime) and another that is dominated by cortical connections (a ?connection-field? regime). Furthermore, he hypothesizes that the dominant mode is determined by a number of intrinsic factors, including cell type, laminar location and stimulus attributes such as contrast. He will perform experiments in anesthetized mice by combining single-unit electrophysiology with optical imaging (using voltage-sensitive dyes) or ?electrical imaging? (with multi-electrode arrays). The stimuli are random sequences of gratings that are varied in phase, orientation and spatial frequency with each stimulus ensemble presented at multiple contrast levels. He thus can simultaneously measure the spike train of a single neuron and the activity of its cortical neighborhood, and to relate both of these to the visual stimulus history. The PI?s experiments will help to reveal how different inputs are weighted by V1 neurons and how this might differ for different cell classes or for cells in different lamina. In addition, this research will serve to advance the mouse as an experimental model for vision research, thereby reducing the future need for primate-based research.