Mental imagery and perception overlap within transmodal association networks

Human cognition relies on two modes: a perceptually-coupled mode where mental states are driven by sensory input and a perceptually-decoupled mode featuring self-generated mental content. Imagined states that evoke mental imagery are thought to be supported primarily by reinstated activity in sensory cortex, but transmodal systems are also implicated in imagery-related processes like mind-wandering, recollection, and imagining the future. During a precision fMRI experiment, participants imagined different scenarios in the scanner, then rated their mental states using multi-dimensional experience sampling. Thinking involving scenes evoked activity within the default network, while imagining speech evoked activity within the language network. In each domain, imagining-related activity overlapped with activity evoked by viewing scenes or listening to speech, respectively; however, this overlap was predominantly within transmodal association networks, rather than adjacent unimodal sensory networks. We conclude that the engagement of transmodal networks supports self-generated mental states involving different forms of mental imagery.