title: Independent effects of simultaneous inputs from the saccule and lateral semicircular canal. Evaluation using VEMPs.
abstract: OBJECTIVE
  To determine the effects of stimulation of bilateral lateral semicircular canals (LSCCs) by accelerated rotation and caloric stimulation of unilateral LSCC on vestibular evoked myogenic potentials (VEMPs) in healthy volunteers.
  
  
  METHODS
  In experiment 1, VEMPs were recorded while subjects (n = 11) were seated in a rotational chair and angular acceleration around the earth-vertical axis was provided. Amplitudes of p13-n23 were corrected using background muscle activities. In experiment 2, subjects (n = 8) in the semilateral position kept the LSCC in the vertical position and activated the sternocleidomastoid muscle by twisting the neck. After irrigating the external auditory canal with ice water, VEMPs were recorded on the irrigated side. In experiment 3, the same setting as experiment 2 was applied (n = 6), and hot water of 44 degrees C was used for irrigation.
  
  
  RESULTS
  There were no significant differences in latencies of p13 or n23, and in corrected amplitudes by either rotatory or caloric stimulation.
  
  
  CONCLUSIONS
  Simultaneous stimulation of LSCCs has little effect on VEMPs.
  
  
  CONCLUSIONS
  No functional interaction between the saccule and LSCC was detected in VEMPs, although convergence of semicircular canal and otolith nerve inputs onto single vestibular nucleus neurons has been demonstrated electrophysiologically in animal experiments.
authors.affiliation: Department of Otolaryngology Head and Neck Surgery, Faculty of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan. karinos-tky@umin.ac.jp
authors.forename: Shotaro
authors.initials: S
authors.lastname: Karino
authors.forename: Ken
authors.initials: K
authors.lastname: Ito
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ochiai
authors.forename: Toshihisa
authors.initials: T
authors.lastname: Murofushi
mesh_terms: D000328:Adult; D002150:Caloric Tests; D004525:Efferent Pathways / Q000502:physiology*; D004576:Electromyography; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D009046:Motor Neurons / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology; D009334:Neck Muscles / Q000294:innervation / Q000502:physiology*; D010812:Physical Stimulation; D004856:Postural Balance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D012018:Reflex / Q000502:physiology; D012399:Rotation; D012444:Saccule and Utricle / Q000502:physiology*; D012665:Semicircular Canals / Q000502:physiology*; D013116:Spinal Cord / Q000502:physiology; D014725:Vestibular Nerve / Q000502:physiology; D014726:Vestibular Nuclei / Q000502:physiology*