OPTICAL NEUROMODULATION TECHNOLOGY FOR LONG TIMESCALES

描述（由申请人提供）：神经元使用大量不同的信号进行计算，其中毫秒级电脉冲由较慢的膜电位变化和较慢的神经调节剂驱动的信号补充，这些信号在广泛的时间范围内（从几秒到几小时）运行，以控制神经可塑性和神经信息处理。光遗传学（利用光来控制神经组织内遗传定义的细胞）已经能够控制快速电事件，但对神经调节和较慢事件的控制相对未被探索。光遗传学中的这种缺陷代表了巨大的未满足的需求，因为神经调节剂驱动的可塑性可能在帕金森病、成瘾、抑郁和许多其他神经精神过程中很重要，而瞬态电事件根本无法捕获神经信息处理的全部复杂性。释放策略可以释放第二信使，如Ca 2+和cAMP（就像谷氨酸释放可以控制快速电事件）;然而，释放涉及大量应用合成的UV可释放化合物，这些化合物既不适合体内使用，也不适用于驱动遗传靶向的细胞类型。此外，关键的神经调节剂如多巴胺和去甲肾上腺素（大脑根据情况以时间上精确的、脉冲的、相位的或紧张的模式递送）不会招募单个信使，而是作用于靶细胞以招募复杂的细胞内信使结构，这是目前技术无法概括的。因此，没有时间上精确的方法来控制活动物内限定细胞中的神经调节。在目标1中，我们将分子工程新的多功能工具，用于神经调节信号的光学招募，包括那些与几乎所有神经调节系统相关的G蛋白偶联受体的下游。在目标2中，我们将设计长时间尺度电控制的策略，重点是识别和分子优化蛋白质，以产生稳定调制的电状态。在目标3中，我们将调整目标1和目标2中的新工具，用于靶向特定细胞类型中的特定位置，在目标4中，我们将验证新工具，与自由移动小鼠中的自定义光学硬件集成，以测试特定调制模式在行为条件反射中的因果作用。新技术，包括光传感器/效应器，设备和瞄准工具，将1）设计用于不同领域的多功能应用; 2）分发给科学界，3）应用于我们实验室的哺乳动物模型。这种方法利用了我们对电事件的光学控制的工作，但为更广泛的景观打开了大门。事实上，预期的影响是走向跨越时间尺度和模式的网络工程方法，其中复杂的可兴奋组织功能是根据相互作用的电信号和生化信号产生的系统特性来理解的。

DESCRIPTION (provided by applicant): Neurons compute using a vast array of diverse signals, in which millisecond-scale electrical pulses are complemented by slower membrane potential changes and by slower neuromodulator-driven signals that operate over a broad range of timescales (from seconds to hours), to govern neuroplasticity and neural information processing. Optogenetics (the use of light to control genetically-defined cells within neural tissue) has enabled control over fast electrical events, but has left control over neuromodulatory and slower events relatively unexplored. This deficiency in optogenetics represents an enormous unmet need, as neuromodulator-driven plasticity is likely to be important in Parkinson's Disease, addiction, depression, and many other neuropsychiatric processes, while transient electrical events simply do not capture the full complexity of neural information processing. Uncaging strategies can release second messengers such as Ca2+ and cAMP (just as glutamate uncaging can control fast electrical events); however, uncaging involves bulk application of synthetic UV-releasable compounds that are neither suitable for in vivo use, nor useful for driving genetically-targeted cell types. Moreover, key neuromodulators such dopamine and norepinephrine (which the brain delivers in temporally precise, pulsed, phasic or tonic patterns depending on the situation) do not recruit a single messenger, but rather act on target cells to recruit a complex fabric of intracellular messengers that would be impossible to recapitulate with current technologies. Thus, there is no temporally-precise method to control neuromodulation in defined cells within living animals. In Aim 1, we will molecularly engineer novel versatile tools for optical recruitment of neuromodulatory signals, including those downstream of the G-protein coupled receptors linked to virtually every neuromodulator system. In Aim 2, we will engineer strategies for long-timescale electrical control, focusing on identification and molecular optimization of proteins that provide for generation of stably modulated electrical states. In Aim 3, we will adapt the novel tools from Aims 1 and 2 for targeting to specific locations in specific cell types, and in Aim 4, we will validate the novel tools, integrated with custom optical hardware in freely-moving mice, to test the causal roles of specific modulation patterns in behavioral conditioning. The new technologies, encompassing light sensor/effectors, devices, and targeting tools, will be 1) designed for versatile application across diverse fields; 2) distributed to the scientific community, and 3) applied to mammalian models in our laboratory. This approach leverages our work on optical control of electrical events, but opens the door to a much broader landscape. Indeed, the anticipated impact is movement toward a network engineering approach that spans timescales and modalities, in which complex excitable-tissue function is understood in terms of system properties emerging from interacting electrical and biochemical signals.