Mechanisms of interval timing

间隔计时机制

• 批准号: 10207685
• 负责人: Michael A Crickmore
• 金额: $ 47.26万
• 依托单位: BOSTON CHILDREN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-23 至 2023-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10207685
• 关键词: Animals; Automobile Driving; Behavior; Behavior Disorders; Behavioral; Biochemical; Brain; Calcium; Calcium Channel; Circadian Rhythms; Consensus; Cyclic AMP; Data; Disease; Down-Regulation; Drosophila genus; Event; Feedback; Female; Genes; Genetic Transcription; Goals; Hour; Human; Image; Intervention; Life; Measures; Membrane; Memory; Mental disorders; Molecular; Monitor; Mood Disorders; Motivation; Nervous system structure; Neurons; Neuropeptides; Neurosciences; Output; Partner in relationship; Process; Reporting; Role; Signal Transduction; System; Testing; Time; Translating; Work; addiction; base; calmodulin-dependent protein kinase II; circadian pacemaker; cognitive process; design; falls; insight; male; mating behavior; millisecond; neural network; novel; phosphoric diester hydrolase; prevent; screening; sperm cell; time interval; tool; voltage

Project Summary Understanding how neuronal networks construct long lasting and slowly evolving states is an outstanding problem in behavioral neuroscience, both basic and disease-related. My lab focuses on motivation, as its dysregulation is central to addiction and mood disorders. Motivations evolve over minutes to hours, much longer than the timescale of standard neuronal processes, with membrane capacitive time constants of 10-100 milliseconds. The circadian clock keeps intracellular time through transcriptional and translational oscillators, but this mechanism is likely too slow to accurately measure the shorter time periods relevant for most behaviors. We have recently developed mating duration in Drosophila as a powerful system for exploring a change in motivation over time as behavioral goals are achieved. At six minutes into the mating, sperm is transferred from the male to the female and a dramatic shift takes place within the male's nervous system: he will no longer sacrifice his life to sustain the mating. These simultaneous events are caused by the output of four male-specific neurons that produce the neuropeptide Corazonin (Crz). If the Crz neurons are inhibited sperm is not transferred and the male does not downregulate his motivation, leading to matings that last for hours instead of the usual ~23 minutes. We exploit the robustness, experimental tractability, and neuronal localization of these phenomena to gain insights into the molecular and circuit bases of interval timing. Our preliminary data point to CaMKII as a molecular interval timer that functions to delay the activity of the Crz neurons for the first six minutes of mating. The timer works through the gradual decay of sustained autophosphorylation following an initial rise in calcium. This proposal centers on understanding i) how the decay rate of CaMKII is tuned to measure out various time intervals in different neurons, and ii) how the CaMKII timer is read out and translated into a timed signal. We have identified multiple candidate factors that may work to sculpt the rise and fall of CaMKII activity, and thereby set the time interval to be measured. For the timing mechanism itself, I propose to test the hypothesis that CaMKII activation prevents the accumulation of cyclic AMP that would otherwise arise from mutual excitation within the Crz network during mating. The decay of CaMKII activity allows super-threshold cyclic AMP accumulation, leading to a large calcium influx that synchronizes the four Crz neurons and generates a single event that drives sperm transfer and the shifts the motivational state at six minutes after the initiation of mating. This would be the first mechanistic description of a neuronal interval timing system. The high conservation and ubiquitous expression of the molecules involved suggest similar functions in long-lasting brain functions across the animal kingdom, including humans.

项目概要 了解神经元网络如何构建持久且缓慢演化的状态是一项杰出的研究 行为神经科学的问题，包括基础问题和疾病相关问题。我的实验室专注于动机，因为它 失调是成瘾和情绪障碍的核心。动机会在几分钟到几小时甚至更长的时间内演变 比标准神经元过程的时间尺度，膜电容时间常数为 10-100 毫秒。生物钟通过转录和翻译振荡器保持细胞内的时间，但是 这种机制可能太慢，无法准确测量与大多数行为相关的较短时间段。 我们最近开发了果蝇的交配持续时间，作为探索交配持续时间变化的强大系统。 随着行为目标的实现，动机会随着时间的推移而增加。交配六分钟后，精子从 从男性到女性，男性的神经系统发生了戏剧性的转变：他将不再 牺牲自己的生命来维持交配。这些同时发生的事件是由四个男性特有的输出引起的 产生神经肽 Corazonin (Crz) 的神经元。如果 Crz 神经元受到抑制，精子就不会转移 并且雄性不会下调其动机，导致交配持续数小时，而不是通常的情况 〜23分钟。我们利用这些现象的鲁棒性、实验易处理性和神经元定位 深入了解间隔定时的分子和电路基础。 我们的初步数据表明 CaMKII 作为分子间隔计时器，其功能是延迟 Crz 的活动 交配前六分钟的神经元。计时器通过持续的逐渐衰减来工作 钙初始升高后发生自磷酸化。该提案的重点是理解 i）如何衰减 调整 CaMKII 的速率以测量不同神经元中的不同时间间隔，以及 ii) CaMKII 计时器如何 被读出并转换成定时信号。我们已经确定了多个可能起作用的候选因素 塑造 CaMKII 活性的上升和下降，从而设定要测量的时间间隔。为了计时 机制本身，我建议检验 CaMKII 激活防止循环积累的假设 否则，交配过程中 Crz 网络内的相互激励会产生 AMP。的衰败 CaMKII 活性允许超阈值环 AMP 积累，导致大量钙流入， 同步四个 Crz 神经元并生成一个驱动精子转移和转移的单一事件 交配开始后六分钟的动机状态。这将是第一个机械描述 神经元间隔计时系统。所涉及分子的高度保守性和普遍表达 表明包括人类在内的动物界的长期大脑功能具有类似的功能。