Jacobs Joshua, Kahana Michael J, Ekstrom Arne D, Fried Itzhak
Neuroscience Graduate Group, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
J Neurosci. 2007 Apr 4;27(14):3839-44. doi: 10.1523/JNEUROSCI.4636-06.2007.
A growing body of animal research suggests that neurons represent information not only in terms of their firing rates but also by varying the timing of spikes relative to neuronal oscillations. Although researchers have argued that this temporal coding is critical in human memory and perception, no supporting data from humans have been reported. This study provides the first analysis of the temporal relationship between brain oscillations and single-neuron activity in humans. Recording from 1924 neurons, we find that neuronal activity in various brain regions increases at specific phases of brain oscillations. Neurons in widespread brain regions were phase locked to oscillations in the theta- (4-8 Hz) and gamma- (30-90 Hz) frequency bands. In hippocampus, phase locking was prevalent in the delta- (1-4 Hz) and gamma-frequency bands. Individual neurons were phase locked to various phases of theta and delta oscillations, but they only were active at the trough of gamma oscillations. These findings provide support for the temporal-coding hypothesis in humans. Specifically, they indicate that theta and delta oscillations facilitate phase coding and that gamma oscillations help to decode combinations of simultaneously active neurons.
越来越多的动物研究表明，神经元不仅通过其放电频率来表征信息，还通过改变相对于神经元振荡的尖峰时间来表征信息。尽管研究人员认为这种时间编码在人类记忆和感知中至关重要，但尚未有来自人类的支持数据报道。这项研究首次分析了人类大脑振荡与单神经元活动之间的时间关系。通过记录1924个神经元，我们发现不同脑区的神经元活动在脑振荡的特定阶段会增加。广泛脑区的神经元与theta（4 - 8赫兹）和gamma（30 - 90赫兹）频段的振荡存在锁相。在海马体中，锁相主要存在于delta（1 - 4赫兹）和gamma频段。单个神经元与theta和delta振荡的不同相位存在锁相，但它们仅在gamma振荡的波谷处活跃。这些发现为人类的时间编码假说提供了支持。具体而言，它们表明theta和delta振荡促进相位编码，而gamma振荡有助于解码同时活跃的神经元组合。
