I can see where you would be: Patterns of fMRI activity reveal imagined landmarks

Visual mental imagery arises when perceptual information is accessed from memory, originating the experience of "seeing with the mind's eye". Different content-dependent brain areas in the human ventral visual stream are activated during visual mental imagery, similarly to what happens during visual perception. The neural patterns within these regions, but not in the early visual cortex, are similar during imagery and perception, suggesting that, in the absence of perceptual stimulation, content-dependent brain areas are able to re-instantiate specific neural patterns allowing for mental imagery. However, it remains unknown whether these areas contain adequate neural representations that create mental images or need to interact with other regions in the brain, such as the hippocampus (HC), to access the necessary information from memory. To test this hypothesis, we used functional magnetic resonance imaging and both multivoxel pattern classification and psychophysiological interaction analyses. Participants were scanned while viewing or imagining scenes of familiar environments. We found that the identity of familiar places can be decoded from the neural patterns in the parahippocampal place area (PPA), retrosplenial complex/parieto-occipital sulcus (RSC/POS) and HC, during both imagery and perception, and that item-specific information from perceived places was re-instantiated during mental imagery of the same places and vice versa. Furthermore, the right PPA significantly interacted with the right HC and RSC/POS according to the performed task. Specifically, the functional coupling between PPA and HC was higher during mental imagery, whereas the functional coupling between PPA and RSC/POS was higher during perception. Our investigation provides an important contribution to the understanding of how the brain uses previously acquired knowledge to build a mental representation of the world.