Mobile Brain/Body Imaging of Spatial Navigation
Human Cognitive and Systems Neuroscience
Final Report Abstract
The project „Bildgebung menschlicher Hirnaktivität während aktiver räumlicher Orientierung“ investigated human brain dynamics in participants physically moving through space. The goal was to investigate the electrocortical dynamics that are associated with processing of visual, vestibular, and proprioceptive sensory feedback during full body motion to contrast the results with brain dynamics recorded during traditional stationary desktop experiments. To this end, a Mobile Brain/Body Imaging (MoBI) approach was used, synchronizing high-density electroencephalography (EEG) with motion capture and head mounted virtual reality (VR). Two experiments were/are conducted in the Berlin Mobile Brain/Body Imaging lab (BeMoBIL) with 150 m2 to allow participants to move freely in virtual spaces and to navigate their surroundings. A first experiment focusing on the behavioral and brain dynamics associated with rotation only revealed striking differences in a stationary setup where rotations were based on visual flow only as compared to full physical rotations. Performance data revealed a clear performance advantage for participants physically rotating (MoBI setup) and adjusting their initial heading after outward rotations between 30 and 150 degrees to the left or the right as compared to rotations based on visual flow only (desktop setup). The stationary EEG results replicated previous findings of prominent alpha desynchronizations during rotation. In contrast, no alpha desynchronization but a strong synchronization in a wide frequency range from low theta to higher alpha was observed during physical rotations most pronounced in the retrosplenial complex (RSC). This brain region is assumed to integrate idiothetic information from different senses including the vestibular system. Information about rotation in space is used to i) compute heading direction and to ii) integrate this egocentric information with allocentric information about the environment. The strong theta synchronization during physical rotation points to functionally different frequency modulation in actively behaving participants based on the integration of sensory feedback stemming from the movement itself. A second experiment collects data in a path integration task (triangulation) that integrates rotation on the spot as well as translation before and after a rotation. Data recordings are ongoing and the data will be analyzed with a focus on the RSC and associated brain regions processing sensory information that is altered through active behavior and contrasted with a traditional desktop setup providing only visual flow.
Publications
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Heading computation in the human retrosplenial complex during full-body rotation. biorxiv, 417972.
Gramann, K., Hohlefeld, F. U., Gehrke, L., & Klug, M.
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A Bayesian framework for unifying data cleaning, source separation and imaging of electroencephalographic signals. bioRxiv, 559450.
Ojeda, A., Klug, M., Kreutz-Delgado, K., Gramann, K., Mishra, J.
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Identifying key factors for improving ICA-based decomposition of EEG data in mobile and stationary experiments. European Journal of Neuroscience, Early View, Online Version of Record before inclusion in an issue.
Klug, M., & Gramann, K.
