International Neuroscience Doctoral Programme, Champalimaud Neuroscience Programme, Champalimaud Centre for the Unknown Lisbon, Portugal ; Department of Otorhinolaryngology/Head and Neck Surgery, University Medical Center Groningen, University of Groningen Groningen, Netherlands.
Department of Otorhinolaryngology/Head and Neck Surgery, University Medical Center Groningen, University of Groningen Groningen, Netherlands ; National Institute for Health Research, Nottingham Hearing Biomedical Research Unit, School of Medicine, University of Nottingham Nottingham, UK.
Front Neurosci. 2013 Dec 27;7:264. doi: 10.3389/fnins.2013.00264. eCollection 2013.
The effect of unattended task-irrelevant auditory stimuli in the context of an auditory task is not well understood. Using human functional magnetic resonance imaging (fMRI) we compared blood oxygenation level dependent (BOLD) signal changes resulting from monotic task-irrelevant stimulation, monotic task-relevant stimulation and dichotic stimulation with an attended task-relevant stream to one ear and an unattended task-irrelevant stream to the other ear simultaneously. We found strong bilateral BOLD signal changes in the auditory cortex (AC) resulting from monotic stimulation in a passive listening condition. Consistent with previous work, these responses were largest on the side contralateral to stimulation. AC responses to the unattended (task-irrelevant) sounds were preferentially contralateral and strongest for the most difficult condition. Stronger bilateral AC responses occurred during monotic passive-listening than to an unattended stream presented in a dichotic condition, with attention focused on one ear. Additionally, the visual cortex showed negative responses compared to the baseline in all stimulus conditions including passive listening. Our results suggest that during dichotic listening, with attention focused on one ear, (1) the contralateral and the ipsilateral auditory pathways are suppressively interacting; and (2) cross-modal inhibition occurs during purely acoustic stimulation. These findings support the existence of response suppressions within and between modalities in the presence of competing interfering stimuli.
在听觉任务背景下，未被注意的任务无关听觉刺激的影响尚未得到很好的理解。我们使用人类功能磁共振成像（fMRI）比较了来自单耳刺激的任务无关刺激、任务相关刺激和双耳刺激的血氧水平依赖（BOLD）信号变化，其中一只耳朵有注意任务相关的流，另一只耳朵有未注意任务无关的流。我们发现在被动聆听条件下，单耳刺激会导致听觉皮层（AC）产生强烈的双侧 BOLD 信号变化。与之前的工作一致，这些反应在刺激的对侧最大。在最困难的条件下，对未被注意（任务无关）声音的 AC 反应更偏向于对侧，且最强。与在双耳条件下呈现未被注意的流相比，在单耳被动聆听时，AC 会产生更强的双侧反应，并且注意力集中在一只耳朵上。此外，与基线相比，在所有刺激条件下，包括被动聆听，视觉皮层都显示出负响应。我们的结果表明，在双耳聆听时，当注意力集中在一只耳朵上时，（1）同侧和对侧听觉通路会产生抑制性相互作用；（2）在纯声学刺激期间会发生跨模态抑制。这些发现支持在存在竞争干扰刺激的情况下，模态内和模态间存在反应抑制。
