Previous studies have reported that some objects evoke a sense of local three-dimensional space (space-defining; SD), while others do not (space-ambiguous; SA), despite being imagined or viewed in isolation devoid of a background context. Moreover, people show a strong preference for SD objects when given a choice of objects with which to mentally construct scene imagery. When deconstructing scenes, people retain significantly more SD objects than SA objects. It therefore seems that SD objects might enjoy a privileged role in scene construction. In the current study we compared the neural responses to SD and SA objects while they were being used to build imagined scene representations, as this has not been examined before using neuroimaging. On each trial, participants gradually built a scene image from three successive auditorily-presented object descriptions and an imagined 3D space. In order to capture the neural dynamics associated with the points during scene construction when either SD or SA objects were being imagined, we leveraged the high temporal resolution of magnetoencephalography. We found that while these object types were being imagined during scene construction, SD objects elicited theta changes relative to SA objects in two brain regions, the ventromedial prefrontal cortex (vmPFC) and superior temporal gyrus (STG). Furthermore, using dynamic causal modelling, we observed that the vmPFC drove STG activity. These results indicate that SD objects were processed differently to SA objects, and we suggest that SD objects may activate schematic and conceptual knowledge in vmPFC and STG upon which scene representations are built.
bioRxiv Subject Collection: Neuroscience