单耳和双耳对人类听觉皮层耳间水平差异敏感性的贡献。

Monaural and binaural contributions to interaural-level-difference sensitivity in human auditory cortex.

作者信息

Stecker G Christopher, McLaughlin Susan A, Higgins Nathan C

机构信息

Department of Hearing and Speech Sciences, Vanderbilt University School of Medicine, Nashville, TN, USA.

Institute for Learning and Brain Sciences, University of Washington, Seattle, WA, USA.

出版信息

Neuroimage. 2015 Oct 15;120:456-66. doi: 10.1016/j.neuroimage.2015.07.007. Epub 2015 Jul 9.

Abstract

Whole-brain functional magnetic resonance imaging was used to measure blood-oxygenation-level-dependent (BOLD) responses in human auditory cortex (AC) to sounds with intensity varying independently in the left and right ears. Echoplanar images were acquired at 3 Tesla with sparse image acquisition once per 12-second block of sound stimulation. Combinations of binaural intensity and stimulus presentation rate were varied between blocks, and selected to allow measurement of response-intensity functions in three configurations: monaural 55-85 dB SPL, binaural 55-85 dB SPL with intensity equal in both ears, and binaural with average binaural level of 70 dB SPL and interaural level differences (ILD) ranging ±30 dB (i.e., favoring the left or right ear). Comparison of response functions equated for contralateral intensity revealed that BOLD-response magnitudes (1) generally increased with contralateral intensity, consistent with positive drive of the BOLD response by the contralateral ear, (2) were larger for contralateral monaural stimulation than for binaural stimulation, consistent with negative effects (e.g., inhibition) of ipsilateral input, which were strongest in the left hemisphere, and (3) also increased with ipsilateral intensity when contralateral input was weak, consistent with additional, positive, effects of ipsilateral stimulation. Hemispheric asymmetries in the spatial extent and overall magnitude of BOLD responses were generally consistent with previous studies demonstrating greater bilaterality of responses in the right hemisphere and stricter contralaterality in the left hemisphere. Finally, comparison of responses to fast (40/s) and slow (5/s) stimulus presentation rates revealed significant rate-dependent adaptation of the BOLD response that varied across ILD values.

摘要

全脑功能磁共振成像用于测量人类听觉皮层(AC)对左右耳强度独立变化的声音的血氧水平依赖(BOLD)反应。在3特斯拉磁场下采集回波平面图像,在每12秒的声音刺激块中进行一次稀疏图像采集。双耳强度和刺激呈现率的组合在不同块之间变化,并选择这些组合以测量三种配置下的反应强度函数:单耳55 - 85 dB SPL、双耳强度相等的55 - 85 dB SPL以及双耳平均水平为70 dB SPL且耳间水平差异(ILD)在±30 dB范围内(即偏向左耳或右耳)。对侧强度相等的反应函数比较显示,BOLD反应幅度:(1)通常随对侧强度增加,这与对侧耳对BOLD反应的正向驱动一致;(2)对侧单耳刺激的反应幅度大于双耳刺激,这与同侧输入的负面影响(如抑制)一致,这种影响在左半球最强;(3)当对侧输入较弱时,也随同侧强度增加,这与同侧刺激的额外正向影响一致。BOLD反应在空间范围和总体幅度上的半球不对称性通常与先前的研究一致,先前研究表明右半球反应的双侧性更强,左半球的对侧性更严格。最后,对快速(40次/秒)和缓慢(5次/秒)刺激呈现率的反应比较显示,BOLD反应存在显著的速率依赖性适应,且这种适应随ILD值而变化。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/185b/4589528/feb49f3983f0/nihms719348f1.jpg

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