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Visual perception of one's own body under vestibular stimulation using biometric self-avatars in virtual reality
Hans-Otto Karnath1,2, Simone Claire Mölbert1,3,4, Anna Katharina Klaner1
1Centre of Neurology, Division of Neuropsychology, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.
Background And Purpose:
Vestibular input is projected to "multisensory (vestibular) cortex" where it converges with input from other sensory modalities. It has been assumed that this multisensory integration enables a continuous perception of state and presence of one's own body. The present study thus asked whether or not vestibular stimulation may impact this perception.
Methods:
We used an immersive virtual reality setup to realistically manipulate the length of extremities of first person biometric avatars. Twenty-two healthy participants had to adjust arms and legs to their correct length from various start lengths before, during, and after vestibular stimulation.
Results:
Neither unilateral caloric nor galvanic vestibular stimulation had a modulating effect on the perceived size of own extremities.
Conclusion:
Our results suggest that vestibular stimulation does not directly influence the explicit somatosensory representation of our body. It is possible that in non-brain-damaged, healthy subjects, changes in whole body size perception are principally not mediated by vestibular information. Alternatively, visual feedback and/or memory may dominate multisensory integration and thereby override possibly existing modulations of body perception by vestibular stimulation. The present observations suggest that multisensory integration and not the processing of a single sensory input is the crucial mechanism in generating our body representation in relation to the external world.