Vestibular primary afferent responses to sound and vibration in the guinea pig.
This study tested whether air-conducted sound and bone-conducted vibration activated primary vestibular afferent neurons and whether, at low levels, such stimuli are specific to particular vestibular sense organs. In response to 500 Hz bone-conducted vibration or 500 Hz air-conducted sound, primary vestibular afferent neurons in the guinea pig fall into one of two categories--some neurons show no measurable change in firing up to 2 g peak-to-peak or 140 dB SPL. These are semicircular canal neurons (regular or irregular) and regular otolith neurons. In sharp contrast, otolith irregular neurons show high sensitivity: a steep increase in firing as stimulus intensity is increased. These sensitive neurons typically, but not invariably, were activated by both bone-conducted vibration and air-conducted sound, they originate from both the utricular and saccular maculae, and their sensitivity underpins new clinical tests of otolith function.
Vestibular Research Laboratory, School of Psychology, The University of Sydney, NSW, Sydney, 2006, Australia. ianc@psych.usyd.edu.au
Ian S
IS
Curthoys
Vedran
V
Vulovic
D000388:Air; D000818:Animals; D001844:Bone Conduction; D006168:Guinea Pigs / Q000502:physiology*; D006801:Humans; D009475:Neurons, Afferent / Q000502:physiology*; D010037:Otolithic Membrane / Q000502:physiology; D011601:Psychophysics; D013016:Sound; D014722:Vestibule, Labyrinth / Q000166:cytology / Q000502:physiology*; D014732:Vibration