J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida 32611, USA.
J Neurosci. 2011 Mar 30;31(13):4935-43. doi: 10.1523/JNEUROSCI.5580-10.2011.
Field potential oscillations in the ∼10 Hz range are known as the alpha rhythm. The genesis and function of alpha has been the subject of intense investigation for the past 80 years. Whereas early work focused on the thalamus as the pacemaker of alpha rhythm, subsequent slice studies revealed that pyramidal neurons in the deep layers of sensory cortices are capable of oscillating in the alpha frequency range independently. How thalamic and cortical generating mechanisms in the intact brain might interact to shape the organization and function of alpha oscillations remains unclear. We addressed this problem by analyzing laminar profiles of local field potential and multiunit activity (MUA) recorded with linear array multielectrodes from the striate cortex of two macaque monkeys performing an intermodal selective attention task. Current source density (CSD) analysis was combined with CSD-MUA coherence to identify intracortical alpha current generators and assess their potential for pacemaking. Coherence and Granger causality analysis was applied to delineate the patterns of interaction among different alpha current generators. We found that (1) separable alpha current generators are located in superficial, granular, and deep layers, with both layer 4C and deep layers containing primary local pacemaking generators, suggesting the involvement of the thalamocortical network, and (2) visual attention reduces the magnitude of alpha oscillations as well as the level of alpha interactions, consistent with numerous reports of occipital alpha reduction with visual attention in human EEG. There is also indication that alpha oscillations in the lateral geniculate cohere with those in V1.
在 10 赫兹左右的频段产生的电场波动被称为阿尔法节律。在过去的 80 年里,阿尔法节律的产生和功能一直是激烈研究的主题。虽然早期的研究工作集中在丘脑作为阿尔法节律的起搏器,但随后的切片研究表明,感觉皮层深层的锥体神经元能够独立地在阿尔法频率范围内振荡。在完整的大脑中,丘脑和皮层的产生机制如何相互作用,以塑造阿尔法振荡的组织和功能仍然不清楚。我们通过分析两只猕猴在执行跨模态选择性注意任务时,用线性阵列多电极从纹状皮层记录的局部场电位和多单位活动(MUA)的层状分布来解决这个问题。电流源密度(CSD)分析与 CSD-MUA 相干性相结合,以确定皮层内的阿尔法电流发生器,并评估它们作为起搏器的潜力。相干性和格兰杰因果关系分析被用来描绘不同阿尔法电流发生器之间相互作用的模式。我们发现:(1)可分离的阿尔法电流发生器位于浅层、颗粒层和深层,包括第 4C 层和深层都包含主要的局部起搏发生器,这表明了丘脑皮质网络的参与;(2)视觉注意力降低了阿尔法振荡的幅度以及阿尔法相互作用的水平,这与人类脑电图中视觉注意力导致枕部阿尔法减少的许多报告一致。还有迹象表明,外侧膝状体的阿尔法振荡与 V1 的阿尔法振荡一致。