BCI R&D Program, Wadsworth Center, New York State Department of Health, Albany, NY, USA; Department of Electrical and Computer Engineering, University of Texas at El Paso, TX, USA.
BCI R&D Program, Wadsworth Center, New York State Department of Health, Albany, NY, USA; Department of Neurology, Albany Medical College, Albany, NY, USA; Department of Computer Science, Graz University of Technology, Graz, Austria.
Neuroimage. 2014 Aug 15;97:188-95. doi: 10.1016/j.neuroimage.2014.04.045. Epub 2014 Apr 21.
Neuroimaging approaches have implicated multiple brain sites in musical perception, including the posterior part of the superior temporal gyrus and adjacent perisylvian areas. However, the detailed spatial and temporal relationship of neural signals that support auditory processing is largely unknown. In this study, we applied a novel inter-subject analysis approach to electrophysiological signals recorded from the surface of the brain (electrocorticography (ECoG)) in ten human subjects. This approach allowed us to reliably identify those ECoG features that were related to the processing of a complex auditory stimulus (i.e., continuous piece of music) and to investigate their spatial, temporal, and causal relationships. Our results identified stimulus-related modulations in the alpha (8-12 Hz) and high gamma (70-110 Hz) bands at neuroanatomical locations implicated in auditory processing. Specifically, we identified stimulus-related ECoG modulations in the alpha band in areas adjacent to primary auditory cortex, which are known to receive afferent auditory projections from the thalamus (80 of a total of 15,107 tested sites). In contrast, we identified stimulus-related ECoG modulations in the high gamma band not only in areas close to primary auditory cortex but also in other perisylvian areas known to be involved in higher-order auditory processing, and in superior premotor cortex (412/15,107 sites). Across all implicated areas, modulations in the high gamma band preceded those in the alpha band by 280 ms, and activity in the high gamma band causally predicted alpha activity, but not vice versa (Granger causality, p<1e(-8)). Additionally, detailed analyses using Granger causality identified causal relationships of high gamma activity between distinct locations in early auditory pathways within superior temporal gyrus (STG) and posterior STG, between posterior STG and inferior frontal cortex, and between STG and premotor cortex. Evidence suggests that these relationships reflect direct cortico-cortical connections rather than common driving input from subcortical structures such as the thalamus. In summary, our inter-subject analyses defined the spatial and temporal relationships between music-related brain activity in the alpha and high gamma bands. They provide experimental evidence supporting current theories about the putative mechanisms of alpha and gamma activity, i.e., reflections of thalamo-cortical interactions and local cortical neural activity, respectively, and the results are also in agreement with existing functional models of auditory processing.
神经影像学方法表明，听觉处理涉及多个大脑区域，包括颞上后回的后部和相邻的大脑外侧裂周区。然而，支持听觉处理的神经信号的详细空间和时间关系在很大程度上尚不清楚。在这项研究中，我们应用一种新的跨个体分析方法，对十名人类受试者大脑表面记录的电生理信号（脑电描记术（ECoG））进行分析。这种方法使我们能够可靠地识别与处理复杂听觉刺激（即连续的音乐片段）相关的 ECoG 特征，并研究它们的空间、时间和因果关系。我们的结果在神经解剖学上与听觉处理有关的位置（即初级听觉皮层）的 alpha（8-12 Hz）和高伽马（70-110 Hz）频段中识别出与刺激相关的调制。具体来说，我们在与初级听觉皮层相邻的区域中识别出与刺激相关的 ECoG 在 alpha 频段的调制，这些区域已知从丘脑接收传入的听觉投射（在总共 15107 个测试部位中，有 80 个）。相比之下，我们不仅在靠近初级听觉皮层的区域中识别出与刺激相关的 ECoG 在高伽马频段的调制，而且在已知参与更高阶听觉处理的其他外侧裂周区以及前运动皮层（在 15107 个部位中，有 412 个）中也识别出与刺激相关的 ECoG 调制。在所有涉及的区域中，高伽马频段的调制比 alpha 频段的调制早 280 毫秒，高伽马频段的活动可以因果预测 alpha 活动，但反之则不能（格兰杰因果关系，p<1e(-8)）。此外，使用格兰杰因果关系的详细分析确定了高级颞上回（STG）内早期听觉通路中高伽马活动与后颞上回之间、后颞上回与下额前皮质之间以及 STG 与前运动皮层之间的因果关系。有证据表明，这些关系反映了直接的皮质-皮质连接，而不是来自丘脑等皮质下结构的共同驱动输入。总之，我们的跨个体分析定义了与音乐相关的大脑活动在 alpha 和高伽马频段之间的空间和时间关系。它们提供了支持 alpha 和伽马活动潜在机制的实验证据，即分别反映丘脑皮质相互作用和局部皮质神经活动，并且结果也与听觉处理的现有功能模型一致。
