Optical Augmentation of Implicit Timing

项目摘要 这是一项探索性/发展性提案（R21），旨在使用新型转基因小鼠探索内隐计时（即无意识计时）的大脑机制，该小鼠能够实现高通量光遗传学和行为。这个话题很重要，因为内隐计时构成了时间预期的基础，而时间预期是几乎所有认知功能的核心。最近的一项人类功能性磁共振成像研究表明，内隐计时发生在下橄榄体中，这是一种投射到小脑的脑干结构。这个实验出乎意料地证明，下橄榄被无意识检测到的刺激时间的100-200 ms偏差激活。我们和其他人提出，下橄榄核独特的生理特性--特别是其神经元在膜电位中产生时钟样阈下振荡（STO）的倾向--是其在内隐计时中作用的生理基础。虽然基于膜生理学，下橄榄作为时钟的假设仍然是假设而不是证明。这个R21提案的目标是探索在体内下橄榄内特异性操纵STO的能力，因为小鼠使用隐式计时来学习感觉事件。这些实验将是对橄榄小脑时钟操作的定时假设的第一次严格测试，这一假设已经争论了25年以上，但现在可以直接使用光遗传学进行测试。内隐计时的一个范例，其中IO已牵连的是经典条件反射的眨眼，我们将使用我们的体内实验。更一般地说，我们的建议将建立多种方法，以实现高通量光遗传学，电生理学和行为，这将具有广泛的实用性。

Project Summary This is an exploratory/developmental proposal (R21) to explore brain mechanisms of implicit timing (i.e. timing without awareness) using a novel transgenic mouse that enables high-throughput optogenetics and behavior. The topic is important, because implicit timing forms the basis of temporal expectancy which is at the core of nearly all cognitive function. A recent human fMRI study demonstrated that implicit timing occurred in the inferior olive, a brainstem structure that projects to the cerebellum. The experiment demonstrated, quite unexpectedly, that the inferior olive was activated by 100-200 ms deviations in the timing of stimuli that were not consciously detected. We, and others, have proposed that the unique physiological properties of the inferior olive ¿ notably, the propensity of its neurons to generate clock-like subthreshold oscillations (STOs) in membrane potential - are a physiological basis for its role in implicit timing. Although grounded in membrane physiology, the hypothesis of the inferior olive as a clock has remained more hypothetical than proven. The goal of this R21 proposal would be to explore the ability to specifically manipulate STOs within the in vivo inferior olive optically as mice learn about sensory events using implicit timing. The experiments would be a first rigorous test of the timing hypothesis of olivocerebellar clock operations, a hypothesis that has been spiritedly debated for over 25 years but now can be tested directly using optogenetics. A paradigm of implicit timing for which the IO has been implicated is classical conditioning of the eyeblink reflex, which we will use for our in vivo experiments. More generally, our proposal will establish multiple methods to enable high-throughput optogenetics, electrophysiology, and behavior that will have wide utility.