High resolution evoked potential imaging of the cortical dynamics of human working memory
High resolution evoked potential imaging of the cortical dynamics of human working memory
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DOI：
10.1016/0013-4694(96)00288-x
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发表时间：
1996-04-01
期刊：
影响因子：
--
通讯作者：
Whitfield, S
中科院分区：
文献类型：
--
作者：
Gevins, A;Smith, ME;Whitfield, S
本研究记录了8名受试者在工作记忆和控制任务中的115个通道的高分辨率诱发电位（EPs）。这些任务要求将每个刺激与之前的刺激在言语或空间属性上进行匹配。所有的刺激都诱发了一个在空间任务中比在言语任务中更大的中央P200电位，并且在工作记忆任务中比在控制任务中更大。频繁的，不匹配的刺激引起了正面的，积极的峰值在305毫秒，是更大的空间WM任务相对于其他任务。无论受试者是否参加了言语或空间刺激属性，非匹配刺激的WM任务也引起了增强的P450电位在左额叶皮层，其次是一个持续的电位在上级顶叶皮层。后P390电位引起的不频繁，匹配刺激的幅度较小的空间和言语WM任务相比，控制任务，是一个中央prestimulus CNV。这些结果表明，工作记忆是一个分布式系统的功能与任务特定和任务无关的组件。损伤研究和粗略的时间分辨率功能成像方法，如PET和fMRI，往往描绘一个相当静态的图片的皮质区域参与的WM任务的性能。相比之下，细粒度的时间分辨率与EP方法成像脑功能提供了一个动态的画面亚秒级的变化，在空间分布的WM效应的过程中的个人试验，以及证据的活动引起的匹配和不匹配的刺激序列内的试验。这种关于WM的时间动态的信息提供了对由其他成像方式提供的细粒度空间分辨率的关键补充。
High resolution evoked potentials (EPs), sampled from 115 channels and spatially sharpened with the finite element deblurring method, were recorded from 8 subjects during working memory (WM) and control tasks. The tasks required matching each stimulus with a preceding stimulus on either verbal or spatial attributes. All stimuli elicited a central P200 potential that was larger in the spatial tasks than in the verbal tasks, and larger in the WM tasks than in the control tasks. Frequent, non-matching stimuli elicited a frontal, positive peak at 305 msec that was larger in the spatial WM task relative to the other tasks. Irrespective of whether subjects attended to verbal or spatial stimulus attributes, non-matching stimuli in the WM tasks also elicited an enhanced P450 potential over the left frontal cortex, followed by a sustained potential over the superior parietal cortex. A posterior P390 potential elicited by infrequent, matching stimuli was smaller in amplitude for both spatial and verbal WM tasks compared to control tasks, as was a central prestimulus CNV. These results indicate that WM is a function of a distributed system with both task-specific and task-independent components. Lesion studies and coarse temporal resolution functional imaging methods, such as PET and fMRI, tend to paint a fairly static picture of the cortical regions which participate in the performance of WM tasks. In contrast, the fine grain time resolution provided by imaging brain function with EP methods provides a dynamic picture of subsecond changes in the spatial distribution of WM effects over the course of individual trials, as well as evidence for differences in the activity elicited by matching and non-matching stimuli within sequences of trials. This information about the temporal dynamics of WM provides a critical complement to the fine-grain spatial resolution provided by other imaging modalities.