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

The claustrum is a thin grey matter structure located between the insular cortexand the putamen. The function of the claustrum is largely unknown with diversehypotheses ranging from multisensory integration and consciousness to attentionand cognitive control. Much research on the function of the claustrum relies oninvasive techniques in animal models, as the claustrum's uniquely thinshape makes it difficult to image non-invasively in human subjects. In thecurrent proof-of-concept study, we used high-resolution ultra-high field (7Tesla) functional magnetic resonance imaging (fMRI) to measure activity in thehuman claustrum during the processing of naturalistic stimuli. We presentedshort video clips as visual only, auditory only, or audiovisual conditions whileparticipants performed a central fixation task. We found distinct visualresponses in both the left and the right claustrum at a consistent spatiallocation across participants, hemispheres, and sessions. We also founddeactivations in response to auditory stimulation. These deactivations wereconfined to the right claustrum and did not overlap with visual activity. Thedeactivation in response to auditory stimulation demonstrates the complexity ofthe claustrum's functional organization and suggests functionaldifferentiation within the claustrum. This is the first study to demonstratesensory-specific effects within the human claustrum. It opens the possibilityfor studying the claustrum's role in higher-level aspects of sensoryprocessing in humans.