Department of Psychology and Logopedics, University of Helsinki, 00014, Helsinki, Finland.
Advanced Magnetic Imaging Centre, Aalto University School of Science, Espoo, Finland.
Brain Struct Funct. 2018 Jun;223(5):2113-2127. doi: 10.1007/s00429-018-1612-6. Epub 2018 Jan 29.
A hierarchical and modular organization is a central hypothesis in the current primate model of auditory cortex (AC) but lacks validation in humans. Here we investigated whether fMRI connectivity at rest and during active tasks is informative of the functional organization of human AC. Identical pitch-varying sounds were presented during a visual discrimination (i.e. no directed auditory attention), pitch discrimination, and two versions of pitch n-back memory tasks. Analysis based on fMRI connectivity at rest revealed a network structure consisting of six modules in supratemporal plane (STP), temporal lobe, and inferior parietal lobule (IPL) in both hemispheres. In line with the primate model, in which higher-order regions have more longer-range connections than primary regions, areas encircling the STP module showed the highest inter-modular connectivity. Multivariate pattern analysis indicated significant connectivity differences between the visual task and rest (driven by the presentation of sounds during the visual task), between auditory and visual tasks, and between pitch discrimination and pitch n-back tasks. Further analyses showed that these differences were particularly due to connectivity modulations between the STP and IPL modules. While the results are generally in line with the primate model, they highlight the important role of human IPL during the processing of both task-irrelevant and task-relevant auditory information. Importantly, the present study shows that fMRI connectivity at rest, during presentation of sounds, and during active listening provides novel information about the functional organization of human AC.
层次化和模块化组织是当前灵长类听觉皮层（AC）模型的一个核心假设，但在人类中缺乏验证。在这里，我们研究了静息状态和主动任务期间的 fMRI 连接是否可以提供有关人类 AC 功能组织的信息。在视觉辨别（即没有定向听觉注意）、音高辨别以及两种音高 n 回记忆任务期间，呈现相同的音高变化声音。基于静息状态 fMRI 连接的分析揭示了一个由六个模块组成的网络结构，这些模块位于上颞平面（STP）、颞叶和下顶叶小叶（IPL）的两个半球中。与灵长类模型一致，在该模型中，高级区域比初级区域具有更多的远程连接，环绕 STP 模块的区域显示出最高的模块间连接性。多元模式分析表明，视觉任务与静息状态之间（由视觉任务期间的声音呈现驱动）、听觉任务与视觉任务之间以及音高辨别与音高 n 回任务之间存在显著的连接差异。进一步的分析表明，这些差异主要是由于 STP 和 IPL 模块之间的连接调制所致。虽然结果总体上与灵长类模型一致，但它们突出了人类 IPL 在处理无关和相关听觉信息时的重要作用。重要的是，本研究表明，静息状态、呈现声音期间以及主动聆听期间的 fMRI 连接提供了有关人类 AC 功能组织的新信息。
