Department of Clinical Neurophysiology, Georg-August University of Göttingen, Robert Koch Str 40, 37075 Göttingen, Germany.
J Cogn Neurosci. 2012 Feb;24(2):304-14. doi: 10.1162/jocn_a_00151. Epub 2011 Oct 7.
The temporal maintenance and subsequent retrieval of information that no longer exists in the environment is called working memory. It is believed that this type of memory is controlled by the persistent activity of neuronal populations, including the prefrontal, temporal, and parietal cortex. For a long time, it has been controversially discussed whether, in working memory, the PFC stores past sensory events or, instead, its activation is an extramnemonic source of top-down control over posterior regions. Recent animal studies suggest that specific information about the contents of working memory can be decoded from population activity in prefrontal areas. However, it has not been shown whether the contents of working memory during the delay periods can be decoded from EEG recordings in the human brain. We show that by analyzing the nonlinear dynamics of EEG oscillatory patterns it is possible to noninvasively decode with high accuracy, during encoding and maintenance periods, the contents of visual working memory information within high-gamma oscillations in the human PFC. These results are thus in favor of an active storage function of the human PFC in working memory; this, without ruling out the role of PFC in top-down processes. The ability to noninvasively decode the contents of working memory is promising in applications such as brain computer interfaces, together with computation of value function during planning and decision making processes.
信息在环境中不再存在时的时间维持和随后的检索称为工作记忆。人们认为这种类型的记忆是由神经元群体的持续活动控制的，包括前额叶、颞叶和顶叶皮层。长期以来，关于工作记忆中，PFC 是存储过去的感觉事件，还是其激活是对后区的自上而下控制的非记忆源，一直存在争议。最近的动物研究表明，从前额叶区域的群体活动中可以解码关于工作记忆内容的特定信息。然而，尚未表明是否可以从人类大脑的 EEG 记录中解码工作记忆延迟期间的内容。我们表明，通过分析 EEG 振荡模式的非线性动力学，可以在编码和维持期间，以高精度非侵入性地解码人类 PFC 中的高伽马振荡中视觉工作记忆信息的内容。因此，这些结果支持了人类 PFC 在工作记忆中的主动存储功能；这并没有排除 PFC 在自上而下过程中的作用。在脑机接口等应用中，非侵入性地解码工作记忆内容的能力很有前景，同时可以在规划和决策过程中计算价值函数。
