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Oscillatory activity in parietal and dorsolateral prefrontal cortex during retention in visual short‐term memory: Additive effects of spatial attention and memory load

机译:视觉短时记忆保留期间顶叶和背外侧前额叶皮层的振荡活动:空间注意力和记忆负荷的累加效应

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摘要

We used whole‐head magnetoencephalography to study the representation of objects in visual short‐term memory (VSTM) in the human brain. Subjects remembered the location and color of either two or four colored disks that were encoded from the left or right visual field (equal number of distractors in the other visual hemifield). The data were analyzed using time‐frequency methods, which enabled us to discover a strong oscillatory activity in the 8–15 Hz band during the retention interval. The study of the alpha power variation revealed two types of responses, in different brain regions. The first was a decrease in alpha power in parietal cortex, contralateral to the stimuli, with no load effect. The second was an increase of alpha power in parietal and lateral prefrontal cortex, as memory load increased, but without interaction with the hemifield of the encoded stimuli. The absence of interaction between side of encoded stimuli and memory load suggests that these effects reflect distinct underlying mechanisms. A novel method to localize the neural generators of load‐related oscillatory activity was devised, using cortically‐constrained distributed source‐localization methods. Some activations were found in the inferior intraparietal sulcus (IPS) and intraoccipital sulcus (IOS). Importantly, strong oscillatory activity was also found in dorsolateral prefrontal cortex (DLPFC). Alpha oscillatory activity in DLPFC was synchronized with the activity in parietal regions, suggesting that VSTM functions in the human brain may be implemented via a network that includes bilateral DLPFC and bilateral IOS/IPS as key nodes. Hum Brain Mapp, 2009. © 2009 Wiley‐Liss, Inc.
机译:我们使用全脑磁脑图技术研究人脑中视觉短期记忆(VSTM)中对象的表示。受试者记住了从左或右视野编码的两个或四个彩色盘的位置和颜色(在另一个视野半视野中相等数量的分散器)。使用时频方法对数据进行了分析,这使我们能够在保留间隔内发现8-15 Hz频带中的强烈振荡活动。对阿尔法功率变化的研究揭示了两种类型的反应,分别在不同的大脑区域。首先是与刺激相反的,顶叶皮层的α功率降低,无负荷作用。第二个是随着记忆负荷的增加,顶叶和额叶前额叶皮层中的α光功率增加,但与编码的刺激的半场没有相互作用。编码的刺激的一侧与记忆负荷之间不存在相互作用,表明这些效应反映了不同的潜在机制。使用皮质约束的分布式源定位方法,设计了一种新的方法来定位与负载相关的振荡活动的神经发生器。在下顶壁沟(IPS)和枕骨内沟(IOS)中发现了一些激活。重要的是,在背外侧前额叶皮层(DLPFC)中也发现了强烈的振荡活动。 DLPFC中的α振荡活动与顶区中的活动同步,这表明人脑中的VSTM功能可以通过将双边DLPFC和双边IOS / IPS作为关键节点的网络来实现。嗡嗡的脑图,2009年。©2009 Wiley-Liss,Inc.

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