Abstract
Anticipating the future is a key motif of the brain, possibly supported by mental simulation of upcoming events. Rodent single-cell recordings suggest the ability of spatially tuned cells to represent subsequent locations. Grid-like representations have been observed in the human entorhinal cortex during virtual and imagined navigation. However, hitherto it remains unknown if grid-like representations contribute to mental simulation in the absence of imagined movement. Participants imagined directions between building locations in a large-scale virtual-reality city while undergoing fMRI without re-exposure to the environment. Using multi-voxel pattern analysis, we provide evidence for representations of absolute imagined direction at a resolution of 30° in the parahippocampal gyrus, consistent with the head-direction system. Furthermore, we capitalize on the six-fold rotational symmetry of grid-cell firing to demonstrate a 60° periodic pattern-similarity structure in the entorhinal cortex. Our findings imply a role of the entorhinal grid-system in mental simulation and future thinking beyond spatial navigation.
Highlights
Anticipation of the future is a central adaptive function of the brain and enables adequate decisionmaking and planning
We combined Functional magnetic resonance imaging (fMRI) with multi-voxel pattern analysis and VR to investigate whether the entorhinal grid system contributes to the imagination of directions from stationary viewpoints (Figure 1a,b)
We report two important findings: Firstly, pattern similarity values in the parahippocampal gyrus exhibited a one-fold symmetry congruent with fine-grained representations of imagined facing direction, reflecting the role of this brain region - which has been implicated in spatial processing in the absence of visual input (Wolbers et al, 2011) - in representing the directional aspect of the imagined views
Summary
Anticipation of the future is a central adaptive function of the brain and enables adequate decisionmaking and planning. Before leaving your favorite cafe, you may picture the scenery in front of the cafe in your mind’s eye to determine whether to take a left or a right turn to get home To accomplish this you have to recall both the location of the cafe as well as the direction you are facing when leaving the building. Electrophysiological recordings in freely moving rodents have demonstrated that positional information during navigation is represented by place cells in the hippocampus (O’Keefe and Dostrovsky, 1971) and grid cells in entorhinal cortex (Hafting et al, 2005). Intracranial recordings in patients exploring virtual-reality (VR) environments demonstrated the existence of place and grid cells in the human hippocampus and entorhinal cortex, respectively (Ekstrom et al, 2003; Jacobs et al, 2010, 2013). A 60 ̊ directional periodicity of BOLD-signal modulations in the entorhinal cortex during virtual navigation indicates
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
