High-resolution 7T fMRI reveals the visual zone of the human claustrum

Abstract The claustrum is a thin grey matter structure located between the insular cortex and the putamen. The function of the claustrum is largely unknown with diverse hypotheses ranging from multisensory integration and consciousness to attention and cognitive control. Much research on the function of the claustrum relies on invasive techniques in animal models, as the claustrum’s uniquely thin shape makes it difficult to image non-invasively in human subjects. In the current proof-of-concept study, we used high-resolution ultra-high field (7 Tesla) functional magnetic resonance imaging (fMRI) to measure activity in the human claustrum during the processing of naturalistic stimuli. We presented short video clips as visual only, auditory only, or audiovisual conditions while participants performed a central fixation task. We found distinct visual responses in both the left and the right claustrum at a consistent spatial location across participants, hemispheres, and sessions. We also found deactivations in response to auditory stimulation. These deactivations were confined to the right claustrum and did not overlap with visual activity. The deactivation in response to auditory stimulation demonstrates the complexity of the claustrum’s functional organization and suggests functional differentiation within the claustrum. This is the first study to demonstrate sensory-specific effects within the human claustrum. It opens the possibility for studying the claustrum’s role in higher-level aspects of sensory processing in humans.