Measurement of time-dependent changes in the irregularity of neural spiking
Measurement of time-dependent changes in the irregularity of neural spiking
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DOI：
10.1152/jn.01030.2005
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发表时间：
2006-08-01
影响因子：
2.5
通讯作者：
Baker, Stuart N.
中科院分区：
文献类型：
--
作者：
Davies, Ronnie M.;Gerstein, George L.;Baker, Stuart N.
在锋电位序列中，放电的不规则性与编码过程和信息传递有关，或者被视为噪声。以往对不规则性的研究主要采用峰间期分布的变异系数（CV）。正确估计CV需要恒定的潜在放电率，这是大多数实验情况在试验内或试验间都无法满足的条件。在这里，我们介绍了一种新的不规则性度量的基础上相邻的时间间隔的比率的尖峰序列。新的度量不受发射率的影响，并且在时间上非常局部化，使得它可以用于检查相对于对准标记的不规则性的时间过程。我们的特点与已知特性的模拟尖峰列车的新指标的属性，然后将其应用到从108个单神经元在运动皮层的两只猴子在执行精确的抓地力任务记录的数据。其中五十六个细胞经逆向鉴定为锥体束神经元（PTNs）。61个细胞（30个PTNs）在用对侧手执行任务期间表现出显著的不规则性的时间调制。不规则性调制的信号和潜伏期与放电频率调制的信号和潜伏期不同。高不规则性往往发生在任务阶段，需要最详细的控制运动，而神经放电变得更有规律的稳定保持阶段。这种不规则性调制可能对下游神经元的反应产生重要影响，并可能提供对皮层代码性质的洞察。
Irregularity of firing in spike trains has been associated with coding processes and information transfer or alternatively treated as noise. Previous studies of irregularity have mainly used the coefficient of variation (CV) of the interspike interval distribution. Proper estimation of CV requires a constant underlying firing rate, a condition that most experimental situations do not fulfill either within or across trials. Here we introduce a novel irregularity metric based on the ratio of adjacent intervals in the spike train. The new metric is not affected by firing rate and is very localized in time so that it can be used to examine the time course of irregularity relative to an alignment marker. We characterized properties of the new metric with simulated spike trains of known characteristics and then applied it to data recorded from 108 single neurons in the motor cortex of two monkeys during performance of a precision grip task. Fifty-six cells were antidromically identified as pyramidal tract neurons (PTNs). Sixty- one cells (30 PTNs) exhibited significant temporal modulation of their irregularity during task performance with the contralateral hand. The irregularity modulations generally differed in sign and latency from the modulations of firing rate. High irregularity tended to occur during the task phases requiring the most detailed control of movement, whereas neural firing became more regular during the steady hold phase. Such irregularity modulation could have important consequences for the response of downstream neurons and may provide insight into the nature of the cortical code.