Handedness-dependent functional organizational patterns within the bilateral vestibular cortical network revealed by
V Kirsch1, R Boegle2, D Keeser3
1Department of Neurology, Ludwig-Maximilians Universität, Munich, Germany; Graduate School of Systemic Neuroscience, Ludwig-Maximilians Universität, Munich, Germany; German Center for Vertigo and Balance Disorders-IFB(LMU), Ludwig-Maximilians Universität, Munich, Germany.
Insights
The human vestibular cortex shows handedness-dependent organization, with a specialized core and surrounding multisensory areas. This bilateral network
Area of Science:
- Neuroscience
- Human Brain Imaging
- Vestibular System Research
Background:
- The vestibular cortex is a multisensory network involving the temporo-parietal-insular regions.
- Evidence suggests handedness influences hemispheric lateralization within this network.
Purpose of the Study:
- To investigate handedness-dependent organizational patterns of functional subunits in the human vestibular cortex.
- To identify lateralized and non-lateralized organizational characteristics within vestibular areas.
Main Methods:
- Resting-state functional MRI (fMRI) was used on 60 healthy volunteers (30 left-handed, 30 right-handed).
- A functional connectivity-based parcellation (fCBP) approach involved ICA, mask creation, Re-ICA, and cross-correlation analysis.
Main Results:
- Handedness significantly impacts vestibular cortex organization, showing inter-hemispheric symmetry and varying connectivity to whole-brain resting-state networks (RSNs).
- A core region in the parieto-insular cortex exhibits lateralization, dominant in the right hemisphere for right-handers and left for left-handers.
- Multisensory areas like the superior temporal gyrus and temporo-parietal intersection are well-connected hubs, influenced by adjacent sensory systems.
Conclusions:
- The bilateral cortical vestibular network features a handedness-dependent lateralized core and surrounding symmetric multisensory areas.
- Functional organization appears influenced by neighboring sensory systems, suggesting evolutionary adaptation.
- Asymmetrical organization may reflect recent phylogenetic evolution of multisensory vestibular functions.
Abstract:
Current evidence points towards a vestibular cortex that involves a multisensory bilateral temporo-parietal-insular network with a handedness-dependent hemispheric lateralization. This study aimed to identify handedness-dependent organizational patterns of (lateralized and non-lateralized) functional subunits within the human vestibular cortex areas. 60 healthy volunteers (30 left-handed and 30 right-handed) were examined on a 3T MR scanner using resting state functional MRI (fMRI). The data was analyzed in four major steps using a functional connectivity based parcellation (fCBP) approach: (1) independent component analysis (ICA) on a whole brain level to identify different resting state networks (RSN); (2) creation of a vestibular informed mask from four whole brain ICs that included reference coordinates of the vestibular network extracted from meta-analyses of vestibular neuroimaging experiments; (3) Re-ICA confined to the vestibular informed mask; (4) cross-correlation of the activated voxels within the vestibular subunits (parcels) to each other (P-to-P) and to the whole-brain RSN (P-to-RSN). This approach disclosed handedness-dependency, inter-hemispheric symmetry, the scale of connectedness to major whole brain RSN and the grade of spatial overlap of voxels within parcels (common/unique) as meaningful discriminatory organizational categories within the vestibular cortex areas. This network consists of multiple inter-hemisphere symmetric (not lateralized), well-connected (many RSN-assignments) multisensory areas (or hubs; e.g., superior temporal gyrus, temporo-parietal intersection) organized around an asymmetric (lateralized, "dominant") and functionally more specialized (few RSN-assignments) core region in the parieto-insular cortex. The latter is in the middle, posterior and inferior insula. In conclusion, the bilateral cortical vestibular network contains not only a handedness-dependent lateralized central region concentrated in the right hemisphere in right-handers and left hemisphere in left-handers, but also surrounding inter-hemisphere symmetric multisensory vestibular areas that seem to be functionally influenced by their neighboring sensory systems (e.g., temporo-parietal intersection by the visual system). One may speculate that the development of an asymmetrical organized vestibular subsystem reflects a more recent phylogenetic evolution of various multisensory vestibular functions. The right hemispheric dominance of spatial orientation and its disorders, spatial neglect and pusher syndrome, may serve as examples.
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