Department of Psychology, University of Cambridge, Downing Site, Cambridge, CB2 3EB, UK.
Vicerrectoría de Investigación y Posgrado, Universidad Católica del Maule, Talca, Chile.
Sci Rep. 2021 Jan 27;11(1):2401. doi: 10.1038/s41598-021-81336-y.
Mental imagery is the process through which we retrieve and recombine information from our memory to elicit the subjective impression of "seeing with the mind's eye". In the social domain, we imagine other individuals while recalling our encounters with them or modelling alternative social interactions in future. Many studies using imaging and neurophysiological techniques have shown several similarities in brain activity between visual imagery and visual perception, and have identified frontoparietal, occipital and temporal neural components of visual imagery. However, the neural connectivity between these regions during visual imagery of socially relevant stimuli has not been studied. Here we used electroencephalography to investigate neural connectivity and its dynamics between frontal, parietal, occipital and temporal electrodes during visual imagery of faces. We found that voluntary visual imagery of faces is associated with long-range phase synchronisation in the gamma frequency range between frontoparietal electrode pairs and between occipitoparietal electrode pairs. In contrast, no effect of imagery was observed in the connectivity between occipitotemporal electrode pairs. Gamma range synchronisation between occipitoparietal electrode pairs predicted subjective ratings of the contour definition of imagined faces. Furthermore, we found that visual imagery of faces is associated with an increase of short-range frontal synchronisation in the theta frequency range, which temporally preceded the long-range increase in the gamma synchronisation. We speculate that the local frontal synchrony in the theta frequency range might be associated with an effortful top-down mnemonic reactivation of faces. In contrast, the long-range connectivity in the gamma frequency range along the fronto-parieto-occipital axis might be related to the endogenous binding and subjective clarity of facial visual features.
心理意象是我们从记忆中检索和重组信息以产生“用心灵之眼看到”的主观印象的过程。在社会领域，我们在回忆与他人的相遇或模拟未来的替代社交互动时会想象其他人。许多使用成像和神经生理学技术的研究表明，意象和视觉感知之间的大脑活动存在许多相似之处，并确定了意象的额顶叶、枕叶和颞叶神经成分。然而，对于与社会相关刺激的视觉意象期间这些区域之间的神经连接还没有研究。在这里，我们使用脑电图来研究在视觉面孔意象期间额、顶、枕和颞电极之间的神经连接及其动态。我们发现，自愿进行面孔的视觉意象与额顶电极对之间以及枕顶电极对之间的伽马频带中的长程相位同步有关。相比之下，在枕颞电极对之间的连接中没有观察到意象的影响。枕顶电极对之间的伽马频带同步与想象面孔的轮廓定义的主观评分相关。此外，我们发现，面孔的视觉意象与额部θ频带中的短程前部同步增加有关，这种同步在γ同步的长程增加之前出现。我们推测，θ频带中的局部额部同步可能与面孔的费力自上而下的记忆重新激活有关。相比之下，沿着额顶枕颞轴的γ频带中的长程连接可能与面部视觉特征的内源性绑定和主观清晰度有关。
