Electrophysiological measures of maintaining representations in visual working memory
Electrophysiological measures of maintaining representations in visual working memory
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DOI：
10.1016/s0010-9452(08)70447-7
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发表时间：
2007-01-01
期刊：
影响因子：
3.6
通讯作者：
Vogel, Edward K.
中科院分区：
文献类型：
--
作者：
McCollough, Andrew W.;Machizawa, Maro G.;Vogel, Edward K.
视觉工作记忆（WM）是一种容量有限的记忆系统，主要用于保存即时视觉环境中物体的信息。最近的神经生理学和神经影像学研究已经发现，在WM任务的保留期间，持续的记忆项目特定活动，这种活动可能是维持WM表征的生理基础。在本研究中，我们提出了一种使用事件相关电位（ERPs）的延迟活动电生理测量方法。受试者被要求记住在双侧展示的一个半球中的项目。在记忆阵列启动大约200毫秒后，我们观察到在相对于记忆项目位置的对侧电极位置有一个大的负波。这种活动持续了整个记忆保留期，似乎类似于在猴子单单元和功能磁共振成像（fMRI） WM研究中观察到的延迟活动。对侧延迟活动由存储器阵列中的项目数调制，但对于3到4个项目的阵列达到渐近线。这种活动在不同类别的简单对象中是相似的，并且在错误反应试验中相对于正确反应试验的振幅较小，这表明这种活动对于给定试验中的正确表现是必要的。总之，这些结果似乎表明了视觉WM中维持表征的电生理指标。
Visual working memory (WM) is a limited capacity system which maintains information about objects in the immediate visual environment. Recent neurophysiological and neuroimaging studies have identified sustained memory-item specific activity during the retention period of WM tasks, and this activity may be a physiological substrate of maintaining representations in WM. In the present study, we present an electrophysiological measure of delay activity using event-related potentials (ERPs). Subjects were asked to remember the items in a single hemifield presented within a bilateral display. Approximately 200 msec following the onset of the memory array, we observed a large negative wave at electrode sites that were contralateral with respect to the position of the memory items. This activity persisted throughout the retention period and appears to be an analog to delay activity observed in monkey single-unit and functional magnetic resonance imaging (fMRI) WM studies. The contralateral delay activity is modulated by the number of items in the memory array but reaches asymptote for arrays of 3 to 4 items. This activity is similar across different classes of simple objects and the amplitude is smaller on incorrect response trials relative to correct trials, suggesting that this activity is necessary for correct performance on a given trial. Together, these results appear to indicate an electrophysiological index of the maintained representations in visual WM.