Spike timing codes for motor control

神经科学的一个中心目标是了解大脑中的神经活动模式如何控制行为。在 原则上，神经元可以通过它们的放电率、它们的尖峰的精确定时或两者来编码信息。 然而，几乎所有先前的运动系统研究都完全依赖于尖峰频率来研究运动系统如何在运动中起作用。 大脑控制行为。我们最近证明，在鸣禽的发声运动皮层， 在尖峰模式的毫秒级差异-是更多的信息比即将到来的行为是尖峰 率尽管这表明皮层发放时间的变化可以调节行为， 精确的皮层尖峰定时是否会在运动神经元和肌肉下游驱动类似的精确代码 组织，或者运动神经元尖峰时间的变化是否能够改变行为。的 拟议的实验将结合联合收割机创新的行为，生理和计算技术 为了了解神经系统如何使用精确定时的电活动模式来调节神经系统， 鸣禽发声的声学特性。我们的长期目标是了解大脑中的尖峰活动 控制行为。本建议的目的是确定哪些属性的电机尖峰驱动器的变化 控制鸣禽发声的行为。我们的中心假设是大脑通过以下方式控制行为 精确地（精确到几毫秒）调制尖峰定时。这一假设将在 三个具体目标。在目标1中，我们将使用一种新开发的电极系统来研究 肌肉组织（即，单个运动单位的尖峰，每个运动单位由肌肉纤维组成， 单个运动神经元），以确定鸣禽发声神经肌肉控制的时间尺度。在目标2中， 将使用创新的体内、体外和离体技术来确定尖峰时间差异 观察到肌肉纤维影响运动输出。在目标3中，我们将研究如何精确的射击模式， 协调多块肌肉。所有三个目标将紧密结合实验研究和计算 分析，以确定最强烈影响行为的特定尖峰时间模式，并生成和测试 关于精确运动控制的生物力学基础的假说。这些研究的基本原理是， 将颠覆长期以来的观念，即皮层运动控制仅基于尖峰频率代码，并建立广泛的 适用的框架，用于分析基于时间的尖峰代码内和外的电机系统。 此外，我们的研究结果和技术可能会显着有助于改善神经假体 通过显示解码算法如何利用除了速率信息之外的尖峰定时， 通常用于当前方法中。

A central goal of neuroscience is to understand how patterns of neural activity in the brain control behavior. In principle, neurons can encode information via their firing rates, the precise timing of their spikes, or both. However, nearly all prior studies of motor systems have relied exclusively on spike rates to investigate how the brain controls behavior. We recently demonstrated that in songbird vocal motor cortex, spike timing – down to millisecond-scale differences in spike patterning – is far more informative about upcoming behavior than is spike rate. Although this suggests that variations in cortical spike timing could modulate behavior, it is unknown whether precise cortical spike timing drives a similarly precise code downstream in motor neurons and muscle tissue, or indeed whether variations in motor neuron spike timing are capable of modifying behavior. The proposed experiments will combine innovative behavioral, physiological, and computational techniques to understand how the nervous system uses precisely timed patterns of electrical activity to regulate the acoustics of vocal output in songbirds. Our long-term goal is to understand how spiking activity in the brain controls behavior. The objective of this proposal is to determine which properties of motor spiking drive variations in behavior in control of vocalizations in songbirds. Our central hypothesis is that the brain controls behavior by precisely (down to a precision of a few milliseconds) modulating spike timing. This hypothesis will be tested in three specific Aims. In Aim 1, we will use a newly developed electrode system to study spiking activity from muscle tissue (i.e., the spikes of individual motor units, each of which consists muscle fibers innervated by a single motor neuron) in vocalizing songbirds to determine the timescale of neuromuscular control. In Aim 2, we will use innovative in vivo, in vitro, and ex vivo techniques to determine whether spike-timing differences observed in muscle fibers affect motor output. In Aim 3, we will examine how precise firing patterns are coordinated across multiple muscles. All three Aims will tightly integrate experimental studies and computational analyses to identify specific spike timing patterns that most strongly influence behavior and to generate and test hypotheses about the biomechanical bases of precise motor control. The rationale for these studies is that they will upend long-held notions that cortical motor control is based solely on spike rate codes and establish a broadly applicable framework for analyzing timing-based spike codes both within and beyond the motor system. Furthermore, our findings and techniques may significantly contribute to the improvement of neural prosthetic devices by showing how decoding algorithms might make use of spike timing in addition to the rate information commonly used in current approaches.