Department of Psychiatry, University of California, San Francisco, CA-94143, USA.
Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA-94143, USA.
Sci Rep. 2019 May 2;9(1):6814. doi: 10.1038/s41598-019-43291-7.
Reality monitoring is defined as the ability to distinguish internally self-generated information from externally-derived information. The medial prefrontal cortex (mPFC) is a key brain region subserving reality monitoring and has been shown to be activated specifically during the retrieval of self-generated information. However, it is unclear if mPFC is activated during the encoding of self-generated information into memory. If so, it is important to understand whether successful retrieval of self-generated information critically depends on enhanced neural activity within mPFC during initial encoding of this self-generated information. We used magnetoencephalographic imaging (MEGI) to determine the timing and location of cortical activity during a reality-monitoring task involving self generated contextual source memory encoding and retrieval. We found both during encoding and retrieval of self-generated information, when compared to externally-derived information, mPFC showed significant task induced oscillatory power modulation in the beta-band. During initial encoding of self-generated information, greater mPFC beta-band power reductions occurred within a time window of -700 ms to -500 ms prior to vocalization. This increased activity in mPFC was not observed during encoding of externally-derived information. Additionally, increased mPFC activity during encoding of self-generated information predicted subsequent retrieval accuracy of this self-generated information. Beta-band activity in mPFC was also observed during the initial retrieval of self-generated information within a time window of 300 to 500 ms following stimulus onset and correlated with accurate retrieval performance of self-generated information. Together, these results further highlight the importance of mPFC in mediating the initial generation and awareness of participants' internal thoughts.
现实监控被定义为区分内部自我产生的信息和外部来源信息的能力。内侧前额叶皮层（mPFC）是一个支持现实监控的关键大脑区域，已经证明在检索自我产生的信息时，它会被特异性激活。然而，目前尚不清楚 mPFC 是否在将自我产生的信息编码到记忆中时被激活。如果是这样，那么了解自我生成信息的成功检索是否严重依赖于在初始编码过程中 mPFC 内的神经活动增强就很重要了。我们使用脑磁图（MEGI）来确定涉及自我生成上下文源记忆编码和检索的现实监控任务中皮质活动的时间和位置。我们发现，与外部来源信息相比，在自我产生信息的编码和检索过程中，mPFC 在β波段显示出显著的任务诱导振荡功率调制。在自我生成信息的初始编码过程中，与发声前的-700 ms 到-500 ms 时间窗口相比，mPFC 中的β波段功率减少更大。在外部来源信息的编码过程中，没有观察到这种 mPFC 活动的增加。此外，在自我生成信息编码过程中 mPFC 活动的增加，预测了后续对该自我生成信息的检索准确性。在刺激开始后的 300 到 500 ms 的时间窗口内，mPFC 中的β波段活动也在自我生成信息的初始检索过程中被观察到，并且与自我生成信息的准确检索表现相关。总的来说，这些结果进一步强调了 mPFC 在介导参与者内部思想的初始生成和意识中的重要性。
