Crosson Bruce, McGregor Keith, Gopinath Kaundinya S, Conway Tim W, Benjamin Michelle, Chang Yu-Ling, Moore Anna Bacon, Raymer Anastasia M, Briggs Richard W, Sherod Megan G, Wierenga Christina E, White Keith D
Department of Veterans Affairs Rehabilitation Research and Development Brain Rehabilitation Research Center at the Malcom Randall VA Medical Center, Gainesville, Florida, USA.
Neuropsychol Rev. 2007 Jun;17(2):157-77. doi: 10.1007/s11065-007-9024-z. Epub 2007 May 25.
Animal analogue studies show that damaged adult brains reorganize to accommodate compromised functions. In the human arena, functional magnetic resonance imaging (fMRI) and other functional neuroimaging techniques have been used to study reorganization of language substrates in aphasia. The resulting controversy regarding whether the right or the left hemisphere supports language recovery and treatment progress must be reframed. A more appropriate question is when left-hemisphere mechanisms and when right-hemisphere mechanisms support recovery of language functions. Small lesions generally lead to good recoveries supported by left-hemisphere mechanisms. However, when too much language eloquent cortex is damaged, right-hemisphere structures may provide the better substrate for recovery of language. Some studies suggest that recovery is particularly supported by homologues of damaged left-hemisphere structures. Evidence also suggests that under some circumstances, activity in both the left and right hemispheres can interfere with recovery of function. Further research will be needed to address these issues. However, daunting methodological problems must be managed to maximize the yield of future fMRI research in aphasia, especially in the area of language production. In this review, we cover six challenges for imaging language functions in aphasia with fMRI, with an emphasis on language production: (1) selection of a baseline task, (2) structure of language production trials, (3) mitigation of motion-related artifacts, (4) the use of stimulus onset versus response onset in fMRI analyses, (5) use of trials with correct responses and errors in analyses, and (6) reliability and stability of fMRI images across sessions. However, this list of methodological challenges is not exhaustive. Once methodology is advanced, knowledge from conceptually driven fMRI studies can be used to develop theoretically driven, mechanism-based treatments that will result in more effective therapy and to identify the best patient candidates for specific treatments. While the promise of fMRI in the study of aphasia is great, there is much work to be done before this technique will be a useful clinical tool.
动物类比研究表明，受损的成人大脑会进行重组以适应受损的功能。在人类领域，功能磁共振成像（fMRI）和其他功能性神经成像技术已被用于研究失语症中语言基质的重组。关于右半球还是左半球支持语言恢复和治疗进展的争议必须重新审视。一个更恰当的问题是，左半球机制何时以及右半球机制何时支持语言功能的恢复。小损伤通常会在左半球机制的支持下实现良好的恢复。然而，当太多具有语言表达功能的皮层受损时，右半球结构可能为语言恢复提供更好的基质。一些研究表明，恢复尤其受到受损左半球结构同源物的支持。证据还表明，在某些情况下，左半球和右半球的活动都可能干扰功能恢复。需要进一步的研究来解决这些问题。然而，必须解决令人生畏的方法学问题，以最大限度地提高未来失语症fMRI研究的成果，尤其是在语言产生领域。在这篇综述中，我们涵盖了使用fMRI对失语症语言功能进行成像的六个挑战，重点是语言产生：（1）基线任务的选择，（2）语言产生试验的结构，（3）减轻与运动相关的伪影，（4）在fMRI分析中使用刺激开始与反应开始，（5）在分析中使用正确反应和错误的试验，以及（6）fMRI图像在不同会话之间的可靠性和稳定性。然而，这份方法学挑战清单并不详尽。一旦方法学取得进展，来自概念驱动的fMRI研究的知识就可以用于开发理论驱动的、基于机制的治疗方法，这将带来更有效的治疗，并确定特定治疗的最佳候选患者。虽然fMRI在失语症研究中的前景广阔，但在这项技术成为一种有用的临床工具之前，还有很多工作要做。
