A novel, jitter-based method for detecting and measuring spike synchrony and quantifying temporal firing precision.
A novel, jitter-based method for detecting and measuring spike synchrony and quantifying temporal firing precision.
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DOI：
10.1186/2042-1001-2-5
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发表时间：
2012-05-02
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通讯作者：
Agmon A
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作者：
Agmon A
精确的棘波同步，在毫秒甚至亚毫秒的时间尺度上，已经在不同的大脑区域被报道，但它的神经生物学意义和潜在的机制仍然未知或有争议。由于缺乏一个经过验证的、标准化良好的、稳健的同步量化指标，研究这些问题变得复杂起来。以前使用的同步性测量经常不正确地标准化，因此在不同的实验条件之间不具有可比性，对放电率的变化或两个神经元之间的放电率差异敏感，和/或依赖于放电率平稳性和泊松统计的不成立的假设。我在这里描述了一种新的测量方法，基于抖动的同步指数(JBSI)，它克服了这些问题。JBSI方法基于虚拟尖峰抖动的引入。虽然抖动方法的先前实现仅使用它来检测同步，但JBSI方法也量化同步。抖动方法的先前实现使用计算密集的蒙特卡罗模拟来生成替代尖峰序列，而JBSI是以解析的方式计算的。JBSI方法不假设任何特定的激发模型，也不要求尖峰列锁定在重复的外部刺激上。JBSI可以采用从1(最大可能同步)到−1(最小可能同步)的值，因此被适当地标准化。使用引入受控棘波重合的模拟泊松棘波序列，我证明JBSI是棘波符合率的线性测量，与平均放电频率或两个神经元之间的放电频率差无关，并且对两个神经元的放电速率的共同调制不敏感。相比之下，几个常用的同步索引在这些场景中的一个或多个情况下失败。我还演示了如何使用JBSI来估计系统中的尖峰定时精度。JBSI是一种概念简单、计算高效的方法，可用于计算发射同步的统计意义，将同步量化为一个良好的归一化指标，并估计系统中的时间精度程度。
Precise spike synchrony, at the millisecond or even sub-millisecond time scale, has been reported in different brain areas, but its neurobiological meaning and its underlying mechanisms remain unknown or controversial. Studying these questions is complicated by the lack of a validated, well-normalized and robust index for quantifying synchrony. Previously used measures of synchrony are often improperly normalized and thereby are not comparable between different experimental conditions, are sensitive to variations in firing rate or to the firing rate differential between the two neurons, and/or rely on untenable assumptions of firing rate stationarity and Poisson statistics. I describe here a novel measure, the Jitter-Based Synchrony Index (JBSI), that overcomes these issues. The JBSI method is based on the introduction of virtual spike jitter. While previous implementations of the jitter method used it only to detect synchrony, the JBSI method also quantifies synchrony. Previous implementations of the jitter method used computationally intensive Monte Carlo simulations to generate surrogate spike trains, whereas the JBSI is computed analytically. The JBSI method does not assume any specific firing model, and does not require that the spike trains be locked to a repeating external stimulus. The JBSI can assume values from 1 (maximal possible synchrony) to −1 (minimal possible synchrony) and is therefore properly normalized. Using simulated Poisson spike trains with introduced controlled spike coincidences, I demonstrate that the JBSI is a linear measure of the spike coincidence rate, is independent of the mean firing frequency or the firing frequency differential between the two neurons, and is not sensitive to co-modulations in the firing rates of the two neurons. In contrast, several commonly used synchrony indices fail under one or more of these scenarios. I also demonstrate how the JBSI can be used to estimate the spike timing precision in the system. The JBSI is a conceptually simple and computationally efficient method that can be used to compute the statistical significance of firing synchrony, to quantify synchrony as a well-normalized index, and to estimate the degree of temporal precision in the system.