Neurologic & Cognitive Analysis of Callosotomy Patients

描述(申请人提供)：连接大脑两个半球的胼胝体是人脑中最大的纤维束。这条纤维束在接受完全骨痂切开术的患者中被切断，导致大脑皮质水平的两个半球断开。对这些患者的偏侧化测试可以揭示出感知和认知过程中大脑半球的显著差异，但矛盾的是，他们的行为往往看起来完全整合。这项建议的目的是要调查在大脑半球间整合中，胼胝体和非胼胝体机制所起的作用。有人提出，大脑半球内加工比大脑半球间加工更有效，因此，当任务要求较低时，加工往往发生在一个半球内。然而，随着任务需求的增加，研究表明，另一个半球越来越多地被招募，需要在两个半球之间整合信息和资源。为了确定胼胝体在大脑半球间整合中的作用，我们计划继续对完全膝盖骨切开术患者进行行为测试。此外，我们正在扩大我们的患者群体，以包括那些有部分胼胝体损害的患者，以确定胼胝体亚区在大脑半球间整合中的作用。拟议的实验还纳入了新的方法，特别是扩散张量成像、功能神经成像和神经活动的电生理记录。我们的研究提案围绕四个具体目标展开。第一个目的是研究特定的膝盖骨区域在将视觉特征绑定到统一的物体表征中的作用。第二个目标是探讨半球专门化和任务难度对加工资源配置的影响。第三个目的是考察大脑半球在空间表征上的差异对两个半球之间知觉和运动整合的影响。第四个目标是探索断开连接的两个半球在多大程度上能够监控和响应另一个半球的处理事件。综上所述，这项研究将为了解两个半球的特殊作用以及它们通过胼胝体和非胼胝体机制相互作用的方式提供重要的见解

DESCRIPTION (provided by applicant): The corpus callosum, which connects the two cerebral hemispheres, is the largest fiber tract in the human brain. This fiber tract is severed in patients who undergo complete callosotomy, resulting in a disconnection of the hemispheres at the cortical level. Lateralized testing of these patients can reveal dramatic hemispheric differences in perceptual and cognitive processing, yet paradoxically, their behavior often appears fully integrated. The purpose of this proposal is to investigate the role of the corpus callosum and non-callosal mechanisms in interhemispheric integration. It has been suggested that intrahemispheric processing is more efficient than interhemispheric processing and therefore processing will tend to occur within one hemisphere when task demands are low. As task demands increase, however, research has demonstrated that the other hemisphere is increasingly recruited, requiring integration of information and resources between the two hemispheres. To determine the role of the corpus callosum in interhemispheric integration, we plan to continue behavioral testing of complete callosotomy patients. In addition, we are expanding our patient population to include those with partial lesions of the corpus callosum in order to characterize the role of callosal subregions in interhemispheric integration. Proposed experiments also incorporate new methodologies, specifically, diffusion tensor imaging, functional neuroimaging and electrophysiological recording of neural activity. Our research proposal centers on four specific aims. The first aim is to investigate the role of specific callosal regions in the binding of visual features into unified object representations. The second aim is to explore the effect of hemispheric specialization and task difficulty on the deployment of processing resources. The third aim is to investigate the effect of hemispheric differences in spatial representation on the integration of perception and movement between the two hemispheres. The fourth aim explores the extent to which the disconnected hemispheres are able to monitor and respond to processing events in the other hemisphere. Taken together, this research will provide important insights into the specialized roles of the two hemispheres and the ways in which they interact via the corpus callosum and non-callosal mechanisms