Interrogation of Eye Movement Circuits using fMRI and Optogenetics

描述（由申请人提供）：在神经影像学文献中，关于测量的血氧水平依赖性信号（BOLD）与神经元抑制之间的关系存在很大的知识缺口。控制扫视眼球运动的抑制和释放的基底神经节回路为填补这一知识空白提供了独特的机会。我们建议研究BOLD信号的激活抑制电路参与眼动控制。我们将编码光激活离子通道ChR 2的基因插入基底神经节的输出核中，使它们表达ChR 2。提供给通道表达神经元的光源将打开离子通道并引起抑制性神经元的神经元去极化。将测量BOLD信号。我们有一个特定的目标：确定BOLD信号响应于参与眼动控制的抑制性神经回路的激活。我们将进行三个实验来实现这一目标。1)使用神经元特异性启动子CAG，我们将在黑质网状部（nigra）的神经元中表达ChR 2，并使用fMRI测量BOLD对光激活的反应; 2）使用抑制性神经元特异性启动子（PV和GAD 67）我们将在抑制性黑质神经元中表达ChR 2，并使用fMRI测量响应于光激活的BOLD信号; 3）我们将记录响应于光激活的上丘和丘脑（黑质抑制的靶点）中的电活动（LFP），以比较BOLD响应与电响应。这些实验的结果将揭示抑制的神经处理的关键机制，以及这种基本的神经元活动如何出现在BOLD信号中。

DESCRIPTION (provided by applicant): In the neuroimaging literature, there is a large gap in knowledge regarding the relationship between blood oxygen level dependent signals (BOLD) that are measured and neuronal inhibition. The circuits in the basal ganglia that control the suppression and release of saccadic eye movements provide a unique opportunity to fill this gap in knowledge. We propose to study BOLD signals in response to activation of an inhibitory circuit involved in eye movement control. We will insert genes encoding the light-activated ion channel, ChR2 into an output nucleus of the basal ganglia causing them to express ChR2. A light source provided to the channel- expressing neurons will open ion channels and cause neuronal depolarization of inhibitory neurons. BOLD signals will be measured. We have one Specific Aim: to determine BOLD signals in response to activation of an inhibitory neural circuit involved in eye movement control. We will perform three experiments to achieve this aim. 1) Using the neuron-specific promoter CAG, we will express ChR2 in neurons of the substantia nigra pars reticulata (nigra) and measure BOLD responses to light activation using fMRI; 2) using inhibitory neuron-specific promoters (PV and GAD67) we will express ChR2 in inhibitory nigral neurons and measure BOLD signals in response to light activation using fMRI; 3) we will record the electrical activity (LFPs) in the super colliculus and the thalamus (targets of nigral inhibition) in response to light activation to compare BOLD responses to electrical responses. The results of these experiments will uncover critical mechanisms of neural processing of inhibition and how this fundamental neuronal activity appears in BOLD signals.