Existence of possible functional interaction between the saccule and the posterior semicircular canal in humans: an evaluation using VEMPs.

The purpose of this study was to determine the effects of stimulation of the vertical semicircular canals on vestibular evoked myogenic potentials (VEMPs). VEMPs were recorded in 14 subjects seated with their heads and necks tilted 120 degrees forward on the interaural axis. The head was rotated 45 degrees to the left or right from the sagittal plane; an angular acceleration around the earth's vertical axis was then provided. When the posterior semicircular canal (PSCC) of the recording side was excited, the rotation was defined as 'ipsilateral rotation', and the opposite rotation was defined as 'contralateral rotation'. The background muscle activity-corrected p13-n23 amplitude (CA) in the ipsilateral rotation was significantly smaller than CAs in the static state and the contralateral rotation. Functional interaction between the saccule and the PSCC could be detected.