Abstract
It is widely assumed that perception and mental imagery of high-level visual stimuli engage the same neural circuitry (O’Craven and Kanwisher, 2000). Here, using fMRI, we report surprising evidence to the contrary. First, participants (N=16) performed two localizers: 1) a place memory localizer (memory of places vs. people; Silson and Steel, 2019), and 2) a scene perception localizer (images of scenes vs. faces). At the individual level, these localizers revealed three regions of the brain -- one on each lateral, ventral, and medial surfaces -- that were selectively activated during memory of familiar places, which we refer to as the “place memory network” (PMN). These regions partially overlapped with, but were distinct from, the scene perception network (SPN), including the occipital, parahippocampal, and medial place areas (OPA, PPA, MPA).
We subsequently compared brain activation in the place memory network vs. scene perception network while participants engaged in intermixed trials of a mental imagery vs. scene perception task. Surprisingly, we found that the SPN showed no activation during mental imagery. In fact, two scene regions (PPA and OPA) were significantly deactivated during mental imagery relative to baseline (OPA: p<0.01, PPA: p<0.001). In contrast, all PMN regions were strongly activated during mental imagery (p<0.05), while showing significantly less activity during scene perception than the SPN (p<0.05). A repeated-measures ANOVA revealed a significant interaction between Network (PMN vs. SPN) and Task (Imagery vs. Perception) (ANOVA: p<0.001).
These results suggest that, for scenes, the neural substrates of imagery and perception are distinct: the PMN, rather than the SPN, supports mental imagery of scenes. Given the preferential selectivity of PMN for the memory - not perception - of visual scenes and adjacency to scene perception regions, we hypothesize that these regions may support mental imagery relevant to navigation.