Calvert G A, Brammer M J, Morris R G, Williams S C, King N, Matthews P M
Centre for Functional Magnetic Resonance Imaging of the Brain (FMRIB), John Radcliffe Hospital, Headington, Oxford, OX3 9DU.
Brain Lang. 2000 Feb 15;71(3):391-9. doi: 10.1006/brln.1999.2272.
We have used functional magnetic resonance imaging (fMRI) to characterize brain activations associated with two distinct language tasks performed by a 28-year-old woman after partial recovery from dysphasia due to a left frontal hemispheric ischemic stroke. MRI showed that her ischemic lesion extended posteriorly from the left inferior frontal to the perisylvian cortex. fMRI scans of both language tasks revealed substantial differences in activation pattern relative to controls. The nature of this difference was task-specific. During performance of a verbal semantic decision task, the patient, in contrast to controls, activated a network of brain areas that excluded the inferior frontal gyrus (in either hemisphere). A second task involving rhyme judgment was designed to place a heavier cognitive load on language production processes and activated the left inferior frontal gyrus (Broca's area) strongly in normal controls. During this task, the most prominent frontal activation in the patient occurred in the right homologue of Broca's area. Subsequent analysis of this data by methods able to deal with responses of changing amplitude revealed additional, less sustained recruitment by the patient of cortex adjacent to the infarct in the region inferior to Broca's area during rhyming. These results suggest that in addition to changes in cognitive strategy, recovery from dysphasia could be mediated by both the preservation of neuronal networks in and around the infarct and the use of homologous regions in the contralateral hemisphere.
我们利用功能磁共振成像（fMRI）对一名28岁女性的大脑激活情况进行了特征描述，该女性因左侧额叶半球缺血性中风导致部分失语恢复后，执行了两项不同的语言任务。MRI显示，她的缺血性病变从左侧额下回向后延伸至颞叶周围皮质。两项语言任务的fMRI扫描均显示，与对照组相比，激活模式存在显著差异。这种差异的性质具有任务特异性。在执行言语语义决策任务时，与对照组相比，该患者激活了一个大脑区域网络，其中排除了额下回（双侧半球）。第二项涉及韵律判断的任务旨在对语言生成过程施加更重的认知负荷，在正常对照组中强烈激活了左侧额下回（布罗卡区）。在这项任务中，该患者最显著的额叶激活发生在布罗卡区的右侧同源区域。随后，通过能够处理变化幅度反应的方法对这些数据进行分析，结果显示，在押韵任务期间，该患者对布罗卡区下方梗死区域附近的皮质进行了额外的、持续时间较短的募集。这些结果表明，除了认知策略的变化外，失语症的恢复可能由梗死灶内及周围神经元网络的保留以及对侧半球同源区域的利用共同介导。
