Bookheimer S Y, Zeffiro T A, Blaxton T A, Gaillard W D, Malow B, Theodore W H
Epilepsy Research Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
Neuroreport. 1998 Jul 13;9(10):2409-13. doi: 10.1097/00001756-199807130-00047.
One issue of continuing debate in language research concerns whether the brain holds separate representations for semantic information through the auditory vs visual modalities. Regardless of whether we hear, see or read meaningful information, our brains automatically activate both auditory and visual semantic associations to the sensory input. The prominent models for how the brain makes these cross-modality associations holds that semantic information conveyed through either sensory input modality is represented in a shared semantic system comprising the traditionally identified language areas in the brain. A few recent case reports as well as activation imaging studies, have challenged this notion by demonstrating category-specific organization within the semantic system in spatially discrete brain regions. Neither view posits a role for primary sensory cortices in semantic processing. We obtained positron emission tomographic (PET) images while subjects performed an auditory responsive naming task, an auditory analog to visual object naming. Subjects heard and responded to descriptions of concrete objects while blindfolded to prevent visual stimulation. Our results showed that, in addition to traditional language centers, auditory language input produced reciprocal activation in primary and secondary visual brain regions, just as if the language stimuli had entered in the visual modality. These findings provide evidence for a distributed semantic system in which sensory-specific semantic modules are mutually interactive, operating directly onto early sensory processing centers.
语言研究中持续存在争议的一个问题是，大脑是否通过听觉和视觉模态分别存储语义信息。无论我们是听到、看到还是读到有意义的信息，我们的大脑都会自动将听觉和视觉语义联想与感官输入联系起来。关于大脑如何建立这些跨模态联想的主流模型认为，通过任何一种感官输入模态传达的语义信息都存储在一个共享的语义系统中，该系统由大脑中传统上确定的语言区域组成。最近的一些病例报告以及激活成像研究对这一观点提出了挑战，它们通过在空间上离散的脑区中展示语义系统内特定类别的组织来进行反驳。两种观点都没有假定初级感觉皮层在语义处理中起作用。我们在受试者执行听觉反应命名任务（一种视觉物体命名的听觉模拟任务）时获得了正电子发射断层扫描（PET）图像。受试者在蒙眼以防止视觉刺激的情况下，听到并对具体物体的描述做出反应。我们的结果表明，除了传统的语言中枢外，听觉语言输入在初级和次级视觉脑区产生了相互激活，就好像语言刺激是以视觉模态输入的一样。这些发现为分布式语义系统提供了证据，在该系统中，特定感官的语义模块相互作用，直接作用于早期感官处理中心。
