Institute for Intelligent Systems, University of Memphis, Memphis, TN, USA; School of Communication Sciences & Disorders, University of Memphis, Memphis, TN, USA; University of Tennessee Health Sciences Center, Department of Anatomy and Neurobiology, Memphis, TN, USA.
Institute for Intelligent Systems, University of Memphis, Memphis, TN, USA; Department of Psychology, University of Memphis, Memphis, TN, USA; Department of Mathematical Sciences, University of Memphis, Memphis, TN, USA.
Neuroimage. 2019 Nov 1;201:116022. doi: 10.1016/j.neuroimage.2019.116022. Epub 2019 Jul 13.
To construct our perceptual world, the brain categorizes variable sensory cues into behaviorally-relevant groupings. Categorical representations are apparent within a distributed fronto-temporo-parietal brain network but how this neural circuitry is shaped by experience remains undefined. Here, we asked whether speech and music categories might be formed within different auditory-linguistic brain regions depending on listeners' auditory expertise. We recorded EEG in highly skilled (musicians) vs. less experienced (nonmusicians) perceivers as they rapidly categorized speech and musical sounds. Musicians showed perceptual enhancements across domains, yet source EEG data revealed a double dissociation in the neurobiological mechanisms supporting categorization between groups. Whereas musicians coded categories in primary auditory cortex (PAC), nonmusicians recruited non-auditory regions (e.g., inferior frontal gyrus, IFG) to generate category-level information. Functional connectivity confirmed nonmusicians' increased left IFG involvement reflects stronger routing of signal from PAC directed to IFG, presumably because sensory coding is insufficient to construct categories in less experienced listeners. Our findings establish auditory experience modulates specific engagement and inter-regional communication in the auditory-linguistic network supporting categorical perception. Whereas early canonical PAC representations are sufficient to generate categories in highly trained ears, less experienced perceivers broadcast information downstream to higher-order linguistic brain areas (IFG) to construct abstract sound labels.
为了构建我们的感知世界，大脑将多变的感官线索分类为与行为相关的组合。类别代表在分布式额颞顶-颞部大脑网络中是明显的，但这种神经回路是如何被经验塑造的仍然没有定义。在这里，我们想知道语音和音乐类别是否可能根据听众的听觉经验在不同的听觉语言大脑区域中形成。我们记录了高度熟练（音乐家）和经验较少（非音乐家）的感知者在快速分类语音和音乐声音时的 EEG。音乐家在各个领域都表现出了感知增强，但源 EEG 数据显示，在支持组间分类的神经生物学机制方面存在双重分离。虽然音乐家在初级听觉皮层（PAC）中编码类别，但非音乐家则招募非听觉区域（例如，额下回，IFG）来生成类别级别的信息。功能连接证实，非音乐家的左 IFG 参与度增加反映了从 PAC 到 IFG 的信号路由增强，可能是因为在经验较少的听众中，感觉编码不足以构建类别。我们的研究结果表明，听觉经验调节了支持类别感知的听觉语言网络中特定的参与和区域间通信。虽然早期的典型 PAC 表示足以在高度训练的耳朵中生成类别，但经验较少的感知者会将信息向下游广播到更高阶的语言大脑区域（IFG），以构建抽象的声音标签。
