Medial Prefrontal-Medial Temporal Theta Phase Coupling in Dynamic Spatial Imagery
Article, Other literature type
Bisby, J. A.
Horner, A. J.
Meyer, S. S.
- Publisher: MIT PRESS
mesheuropmc: psychological phenomena and processes
Hippocampal-medial prefrontal interactions are thought to play a crucial role in mental simulation. Notably, the frontal midline / medial prefrontal cortex (mPFC) theta rhythm in humans has been linked to introspective thought and working memory. In parallel, theta rhythms have been proposed to coordinate processing in medial temporal, retrosplenial and parietal cortices during the movement of viewpoint in imagery, extending their association with physical movement in rodent models. Here, we used non-invasive whole-head magnetoencephalography (MEG) to investigate theta oscillatory power and phase-locking during the 18s post-encoding delay period of a spatial working memory task, in which participants imagined previously learned object sequences either: on a blank background (object maintenance); from a first person viewpoint in a scene (static imagery); or moving along a path past the objects (dynamic imagery). We found increases in 4-7 Hz theta power in mPFC when comparing the delay period to a pre-encoding baseline. We then examined whether the mPFC theta rhythm was phase coupled with ongoing theta oscillations elsewhere in the brain. The same mPFC region showed significantly higher theta phase coupling with the posterior medial temporal lobe / retrosplenial cortex (MTL/RSc) for dynamic imagery versus either object maintenance or static imagery. mPFC theta phase coupling was not observed with any other brain region. These results implicate oscillatory coupling between mPFC and MTL / RSc theta rhythms in the dynamic mental exploration of imagined scenes.