Imagining Sounds and Images: Decoding the Contribution of Unimodal and Transmodal Brain Regions to Semantic Retrieval in the Absence of Meaningful Input

Charlotte Murphy, Shirley-Ann Rueschemeyer, Jonathan Smallwood, Elizabeth Jefferies
2018 Journal of Cognitive Neuroscience  
In the absence of sensory information, we can generate meaningful images and sounds from representations in memory. However, it remains unclear which neural systems underpin this process, and whether different types of imagery recruit similar or different neural networks. We asked people to imagine the visual and auditory features of objects, either in isolation (car, dog) or in specific meaning-based contexts (car/dog race). Using an fMRI decoding approach, in conjunction with functional
more » ... tivity analysis, we examined the role of primary auditory/visual cortex and transmodal brain regions. Conceptual retrieval in the absence of external input recruited sensory and transmodal cortex. The response in transmodal regions including anterior middle temporal gyrus was of equal magnitude for visual and auditory features, yet nevertheless captured modality information in the pattern of response across voxels. In contrast, sensory regions showed greater activation for modality-relevant features in imagination (even when external inputs did not differ). These data are consistent with the view that transmodal regions support internallygenerated experiences and that they play a role in integrating perceptual features encoded in memory.
doi:10.1162/jocn_a_01330 pmid:30156502 fatcat:ydzinw2tjvferdomwhol5ryqli