Karbe H, Herholz K, Halber M, Heiss W D
University Hospital, Department of Neurology, Cologne, Germany.
J Cereb Blood Flow Metab. 1998 Oct;18(10):1157-61. doi: 10.1097/00004647-199810000-00012.
The corpus callosum is the largest connection between the functionally asymmetric cerebral hemispheres. The objective of this study was to measure functional activity of callosal fiber tracts during speech processing. We analyzed the regional glucose metabolism of the corpus callosum and of speech-relevant cortical areas in 10 normal individuals at rest and during word repetition. We used three-dimensionally registered magnetic resonance imaging to visualize the individual brain morphology and high-resolution positron emission tomography for metabolic measurements. The task-induced metabolic changes of the callosal midbody and isthmus had a significant negative correlation with key regions of language processing in the left inferior frontal cortex (Brodmann's area 44) and in the right superior temporal cortex (Brodmann's area 22) (e.g., correlation of metabolic changes in the surface aspects of the right Brodmann's area 22 and the callosal midbody/isthmus: r = -0.91, P < 0.001). The study indicates that language processing in asymmetrically organized cortical areas inhibits the reciprocal transcallosal information exchange in favor of the lateralized mental operation. Our data agree with anatomic, electrophysiologic, and pharmacologic experiments that point to the important role of collateral inhibition for the transcallosal information exchange.
胼胝体是功能不对称的大脑半球之间最大的连接结构。本研究的目的是测量言语加工过程中胼胝体纤维束的功能活动。我们分析了10名正常个体在静息状态和单词复述过程中胼胝体及与言语相关的皮质区域的局部葡萄糖代谢情况。我们使用三维配准磁共振成像来可视化个体脑形态，并使用高分辨率正电子发射断层扫描进行代谢测量。胼胝体中部和峡部的任务诱导代谢变化与左侧额下回皮质（布罗德曼44区）和右侧颞上回皮质（布罗德曼22区）语言加工的关键区域呈显著负相关（例如，右侧布罗德曼22区表面与胼胝体中部/峡部代谢变化的相关性：r = -0.91，P < 0.001）。该研究表明，不对称组织的皮质区域中的语言加工抑制了胼胝体间的相互信息交换，以利于偏侧化心理操作。我们的数据与解剖学、电生理学和药理学实验一致，这些实验表明侧支抑制对胼胝体间信息交换具有重要作用。
