A componential analysis of task-switching deficits associated with lesions of left and right frontal cortex
A componential analysis of task-switching deficits associated with lesions of left and right frontal cortex
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DOI：
10.1093/brain/awh169
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发表时间：
2004-07-01
期刊：
影响因子：
14.5
通讯作者：
Robbins, TW
中科院分区：
文献类型：
--
作者：
Aron, AR;Monsell, S;Robbins, TW
诸如任务设定转换等执行功能被认为依赖于额叶皮层。然而，在确定这种高级过程的哪些成分与大脑的哪些（如果有的话）子区域相关时，需要更精确的分析。在最近一项对19名右侧额叶局灶性病变（RF）患者和17名左侧额叶病变（LF）患者的研究中，我们发现，通过停止信号任务测量的反应抑制，会因右侧额下回（IFG）受损而受到特异性干扰。本研究对同一组患者以及匹配的对照组进行了任务转换表现的检测，理由是任务设定转换可能也需要抑制机制。RF患者和LF患者都比对照组表现出明显更大的转换代价（在反应时间和错误方面，转换任务和重复相同任务之间的差异），但显然原因不同。对于RF患者，部分转换缺陷可归因于对刺激引发的不适当反应或任务设定的抑制受损，并且一种转换代价的测量指标与IFG（特别是岛盖部（POp））的损伤可靠相关。对于LF患者，部分转换缺陷可能源于对任务设定的自上而下的控制较弱。自上而下控制的程度与左侧额中回（MFG）的损伤程度可靠相关。这项研究将复杂的任务转换过程的两个成分（任务设定和/或反应的抑制以及任务设定的自上而下控制）分别定位在右侧IFG/POp和左侧MFG。
Executive functions such as task-set switching are thought to depend on the frontal cortex. However, more precision is required in identifying which components of such high-level processes relate to which, if any, subregions of the brain. In a recent study of 19 patients with focal right frontal (RF) lesions and 17 with left frontal (LF) lesions, we found that response inhibition, as measured by the stop-signal task, was specifically disrupted by damage to the right inferior frontal gyrus (IFG). The present study examined task-switching performance in this same group of patients and in matched controls on the grounds that inhibitory mechanisms may also be required to switch task-set. Both RF and LF patients showed significantly larger switch costs (the difference, in reaction time and errors, between changing tasks and repeating the same task) than controls, but apparently for different reasons. For RF patients, a part of the switch deficit could be accounted for by impaired inhibition of inappropriate responses or task-sets triggered by stimuli, and one measure of the switch cost correlated reliably with damage to the IFG, specifically the pars opercularis (POp). For LF patients, a part of the switch deficit may have arisen from weak top-down control of task-set. The degree of top-down control correlated reliably with the extent of damage to the left middle frontal gyrus (MFG). This study localizes two components of the complex task-switching process (inhibition of task-sets and/or responses and top-down control of task-set) to the right IFG/POp and the left MFG respectively.