Optical Augmentation of Implicit Timing

项目摘要 这是一项探索性/发展性提案(R21)，旨在使用一种能够实现高通量光遗传学和行为的新型转基因小鼠来探索隐含计时(即无意识计时)的大脑机制。这个话题很重要，因为内隐时间形成了时间预期的基础，而时间预期几乎是所有认知功能的核心。最近的一项人类功能磁共振研究表明，隐含计时发生在下橄榄核，这是一种投射到小脑的脑干结构。实验非常出人意料地证明，下橄榄是由100-200毫秒的刺激时间偏差激活的，而这些刺激是没有意识到的。我们和其他人已经提出，下橄榄的独特生理特性(特别是其神经元在膜电位中产生时钟样的亚阈值振荡(STO)的倾向)是其在隐含计时中发挥作用的生理基础。尽管以膜生理学为基础，下位橄榄作为时钟的假说仍然更多的是假设而不是证明。这项R21提案的目标将是探索在小鼠使用隐含计时学习感觉事件时，通过光学方式特定操纵体内下橄榄体内STO的能力。这些实验将是对橄榄小脑钟操作时间假说的第一次严格测试，这一假说已经激烈争论了25年，但现在可以直接用光遗传学进行测试。隐含计时的范例已经牵涉到IO是眨眼反射的经典条件反射，我们将用于我们的活体实验。更广泛地说，我们的提案将建立多种方法，以实现高通量光遗传学、电生理学和具有广泛实用价值的行为。

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.