Frequency sensitivity range of the saccule to bone-conducted stimuli measured by vestibular evoked myogenic potentials
Audiology & Speech-Language Pathology; bone conduction; frequency sensitivity range; myogenic potential; nerve; neurons; Neurosciences & Neurology; Otorhinolaryngology; repetition rate; responses; saccule; sound; squirrel-monkey; vestibular; vestibular evoked myogenic potential; vibration
Vestibular evoked myogenic potentials (VEMPs) occurring in cervical muscles after intense sound stimulation conducted by air or bone are thought to be a polysynaptic response of otolith-vestibular nerve origin. We report the results of an experiment to investigate whether acoustic stimulation of the saccule by bone conduction produces VEMPs in which response amplitudes are somewhat sensitive to stimulus frequency, as appears, to be the case with air-conducted stimuli. Prior to this we investigated the effect of stimulation repetition rate on bone-conducted VEMPs (B-VEMPs) at stimulus frequencies of 200 and 400 Hz with five different repetition rates (5, 10, 20, 40, and 80 Hz). B-VEMPs were recorded from 12 normal hearing subjects in response to bone-conducted 70 dB (normal hearing level), 10-ms tone bursts (rise/fall time = 1 ms and plateau time = 8 ms) at frequencies of 100, 200, 400, 800, 1600 and 3200 Hz. Our study showed that B-VEMP amplitudes were highest at 10 Hz but decreased as the repetition rate increased. B-VEMP response amplitudes were found to be maximal for stimulus frequencies from 200 to 400 Hz. This response may contribute to the perception of loud sounds. (C) 2001 Elsevier Science B.V. All rights reserved.
Sheykholeslami K; Kermany M H; Kaga K
Hearing Research
2001
2001-10
Journal Article
<a href="http://doi.org/10.1016/s0378-5955(01)00333-1" target="_blank" rel="noreferrer noopener">10.1016/s0378-5955(01)00333-1</a>
Auditory nerve fiber differences in the normal and neurofilament deficient Japanese quail.
*Mutation; Animals; Auditory; Axons/ultrastructure; Brain Stem; Cochlear Nerve/*pathology/*physiopathology; Coturnix/genetics; Electron; Evoked Potentials; Microscopy; Myelin Sheath/ultrastructure; Nerve Fibers/pathology/physiology; Neurofilament Proteins/*deficiency/*genetics
A primary axonal disease affecting the central and peripheral nervous system was discovered in a mutant strain of the Japanese quail, named quiver (Quv). We have previously demonstrated altered auditory evoked potentials in the neurofilament (NF) deficient quail. In this current study we attempt to find relationships between the auditory evoked potential results and the histo-pathological abnormalities of the auditory neurons. No abnormalities in the external auditory meatus and tympanic cavity were observed in either Quv or control quails and the ganglion cell bodies and their nuclei appeared normal by light microscopy. The myelin staining pattern was found to be similar in both strains with hematoxylin and eosin and Kluver-Barrera staining. The frequency histograms of fiber and axonal diameters of myelinated fibers showed an unimodal pattern in both strains. In Quv quails myelinated fibers and their axoplasm were smaller in diameter than in controls resulting in smaller neural tissue mass. In electron microscopic observation the axons of the Quv quail were composed of mitochondria and microtubules and smooth endoplasmic reticuli. In Quv quail electron micrographs of cochlear nerve myelinated fibers NFs were not seen in the axons and the neuronal cell bodies. Our current findings indicate that the previously reported reduction of conduction velocity of auditory evoked potentials may be due to smaller fiber and/or axonal diameter. The g-ratio, myelin thickness and fiber circularity were found to be the same for both strains. In conclusion, loss of axonal cytoskeletal elements (NFs) correlates well with our electrophysiological findings. Reduced conduction velocity and severely distorted auditory evoked potentials in NF deficient quails seem to be primarily due to axonal hypotrophy.
Sheykholeslami K; Kaga K; Mizutani M
Hearing research
2001
2001-09
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1016/s0378-5955(01)00326-4" target="_blank" rel="noreferrer noopener">10.1016/s0378-5955(01)00326-4</a>