Research Article
Carsten M. Klingner
Abstract
Objective: Here, we investigate whether vertigo and nystagmus is generated at the first stage of vestibular processing in the parieto-insular vestibular cortex (PIVC). Background: It is believed that the PIVC is the first and most important hub for the cortical processing of vestibular information. In this region of the brain, vestibular information from both hemispheres is integrated with somatosensory and visual information. Mismatches among these inputs have been consistently demonstrated to activate the PIVC and the widespread vestibular network. Such mismatches also cause behavioral responses, such as vertigo and nystagmus. However, the role of the PIVC in the generation of these symptoms remains elusive, particularly because behavioral and cortical responses have been found to follow very different time-courses. It therefore remains unclear at which level of information processing vertigo and nystagmus are generated. Methods: We performed functional magnetic resonance imaging (fMRI) on 20 healthy subjects during caloric stimulation at different temperatures. We were particularly interested in the changes in the strengths of PIVC activity under these stimulus conditions. Results: By using a non-inferiority analysis, we demonstrate that activity in the PIVC did not increase with the occurence of vertigo and nystagmus. Conclusions: The current data suggest that perceptions of vertigo and nystagmus are not generated at the first integrative stage in the PIVC. We further speculate that nystagmus originates via a direct interaction of vestibular signals with somatosensory and visual information at a subcortical level.