Center for Mind and Brain, University of California, Davis, 95616, USA.
BMC Neurosci. 2011 Aug 17;12:85. doi: 10.1186/1471-2202-12-85.
Segregating auditory scenes into distinct objects or streams is one of our brain's greatest perceptual challenges. Streaming has classically been studied with bistable sound stimuli, perceived alternately as a single group or two separate groups. Throughout the last decade different methodologies have yielded inconsistent evidence about the role of auditory cortex in the maintenance of streams. In particular, studies using functional magnetic resonance imaging (fMRI) have been unable to show persistent activity within auditory cortex (AC) that distinguishes between perceptual states.
We use bistable stimuli, an explicit perceptual categorization task, and a focused region of interest (ROI) analysis to demonstrate an effect of perceptual state within AC. We find that AC has more activity when listeners perceive the split percept rather than the grouped percept. In addition, within this ROI the pattern of acoustic response across voxels is significantly correlated with the pattern of perceptual modulation. In a whole-brain exploratory test, we corroborate previous work showing an effect of perceptual state in the intraparietal sulcus.
Our results show that the maintenance of auditory streams is reflected in AC activity, directly relating sound responses to perception, and that perceptual state is further represented in multiple, higher level cortical regions.
将听觉场景分割成不同的对象或流是我们大脑面临的最大感知挑战之一。经典的流分离研究采用双稳态声音刺激，这些刺激被感知为单个组或两个单独的组。在过去的十年中，不同的方法学得出了关于听觉皮层在流维持中的作用的不一致证据。特别是，使用功能磁共振成像 (fMRI) 的研究未能在听觉皮层 (AC) 中显示出区分感知状态的持续活动。
我们使用双稳态刺激、明确的感知分类任务和聚焦的感兴趣区域 (ROI) 分析来证明 AC 内感知状态的影响。我们发现，当听众感知分裂感知而不是分组感知时，AC 的活动更多。此外，在这个 ROI 中，跨体素的声学响应模式与感知调制的模式显著相关。在全脑探索性测试中，我们证实了先前的工作，表明在顶内沟中存在感知状态的影响。
我们的结果表明，听觉流的维持反映在 AC 活动中，直接将声音反应与感知联系起来，并且感知状态在多个更高层次的皮质区域中进一步得到表示。
