A utricular origin of frequency tuning to low-frequency vibration in the human vestibular system?
Recent work has demonstrated that the human vestibular system displays a remarkable sensitivity to low-frequency vibration. To address the origin of this sensitivity we compared the frequency response properties of vestibular reflexes to 10ms bursts of air-conducted sound and transmastoid vibration, which are thought to be differentially selective for the saccule and utricle, respectively. Measurements were made using two separate central pathways: vestibular evoked myogenic potentials (VEMPs), which are a manifestation of vestibulo-collic projections, and ocular vestibular evoked myogenic potentials (OVEMPs), which are a manifestation of vestibulo-ocular projections. For both response pathways air-conducted sound and vibration stimuli produced the same patterns of quite different tuning. Sound was characterised by a band-pass tuning with best frequency between 400 and 800Hz whereas vibration showed a low-pass type response with a largest response at 100Hz. Our results suggest that the tuning is at least in part due to properties of end-organs themselves, while the 100Hz best frequency may be a specifically utricular feature.
Todd
Neil P M
NP
University of Manchester, Manchester M60 1QD, UK. neil.todd@manchester.ac.uk
Rosengren
Sally M
SM
Colebatch
James G
JG
D000161:Acoustic Stimulation; D000328:Adult; D000344:Afferent Pathways / Q000502:physiology; D000368:Aged; D001933:Brain Stem / Q000502:physiology; D003391:Cranial Nerves / Q000033:anatomy & histology / Q000502:physiology; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D006309:Hearing / Q000502:physiology*; D006801:Humans; D008297:Male; D009334:Neck Muscles / Q000294:innervation / Q000502:physiology*; D009801:Oculomotor Muscles / Q000294:innervation / Q000502:physiology; D010812:Physical Stimulation; D010897:Pitch Discrimination / Q000502:physiology; D012027:Reflex, Vestibulo-Ocular / Q000502:physiology*; D012444:Saccule and Utricle / Q000033:anatomy & histology / Q000502:physiology*; D014725:Vestibular Nerve / Q000502:physiology*; D014732:Vibration