Radboud University, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands.
Radboud University, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands.
Neuroimage. 2015 Sep;118:256-67. doi: 10.1016/j.neuroimage.2015.06.003. Epub 2015 Jun 6.
Neuronal oscillations are a characteristic feature of neuronal activity and are typically investigated through measures of power and coherence. However, neither of these measures directly reflects the distinctive feature of oscillations: their rhythmicity. Rhythmicity is the extent to which future phases can be predicted from the present one. Here, we present lagged coherence, a frequency-indexed measure that quantifies the rhythmicity of neuronal activity. We use this method to identify the sensorimotor alpha and beta rhythms in ongoing magnetoencephalographic (MEG) data, and to study their attentional modulation. Using lagged coherence, the sensorimotor rhythms become visible in ongoing activity as local rhythmicity peaks that are separated from the strong posterior activity in the same frequency bands. In contrast, using conventional power analyses, the sensorimotor rhythms cannot be identified in ongoing data, nor can they be separated from the posterior activity. We go on to show that the attentional modulation of these rhythms is also evident in lagged coherence and moreover, that in contrast to power, it can be visualised even without an experimental contrast. These findings suggest that the rhythmicity of neuronal activity is better suited to identify neuronal oscillations than the power in the same frequency band.
神经元振荡是神经元活动的一个特征，通常通过测量功率和相干性来研究。然而，这两种方法都不能直接反映振荡的独特特征：它们的节奏性。节奏性是指未来相位可以从前一个相位中预测的程度。在这里，我们提出了滞后相干性，这是一种频率索引的测量方法，用于量化神经元活动的节奏性。我们使用这种方法来识别正在进行的脑磁图（MEG）数据中的感觉运动 alpha 和 beta 节律，并研究它们的注意力调制。使用滞后相干性，感觉运动节律在持续活动中作为局部节奏性峰值显现出来，这些峰值与同一频带中的强烈后活动分离。相比之下，使用传统的功率分析，感觉运动节律在持续数据中无法识别，也无法与后活动分离。我们接着表明，这些节律的注意力调制在滞后相干性中也很明显，而且与功率不同，即使没有实验对比，也可以进行可视化。这些发现表明，与同一频带中的功率相比，神经元活动的节奏性更适合识别神经元振荡。
