Activation of group I metabotropic glutamate receptors (mGluRs) has been suggested to modulate development of auditory neurons. However, the acute effects of mGluR activation on physiological response properties are unclear. To address this, we studied the effects of mGluRs in bushy cells (BCs) of the mammalian anteroventral cochlear nucleus (AVCN). Activation of mGluRs with dihydroxyphenylglycine (DHPG) caused depolarization of BCs in mice as old as P42, but did not affect neurotransmitter release by presynaptic auditory nerve (AN) fibers. Application of mGluR antagonists indicated that mGluRs are tonically active, and are highly sensitive to small elevations in ambient glutamate by the glutamate reuptake blocker threo-β-benzyloxyaspartic acid (TBOA). mGluR-mediated depolarization enhanced the firing probability in response to AN stimulation, and reduced the latency and jitter. Furthermore, excitation through postsynaptic mGluRs can significantly counterbalance the inhibitory effects of presynaptic GABA(B) receptors. Thus, interaction between these two modulatory pathways may provide additional flexibility for fine-tuning the BC relay.
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http://dx.doi.org/10.1523/JNEUROSCI.1193-11.2011 | DOI Listing |
Cochlear Implants Int
December 2024
Department of ENT and Head & Neck Surgery, Seth GS Medical College & K.E.M. Hospital, Mumbai, India.
Introduction: Wolfram syndrome, a rare autosomal recessive disorder, is characterised by diabetes insipidus, juvenile diabetes mellitus, optic nerve atrophy and deafness (DIDMOAD).
Case Report: We present a case of a 21-year-old male diagnosed with Wolfram syndrome who underwent cochlear implantation due to progressive hearing loss. The patient first complained of bilateral hearing loss at the age of 8 years.
Ear Hear
December 2024
Department of Medical Bionics, University of Melbourne, Melbourne, Australia.
Objectives: Cochlear implants (CIs) have revolutionized hearing restoration for individuals with severe or profound hearing loss. However, a substantial and unexplained variability persists in CI outcomes, even when considering subject-specific factors such as age and the duration of deafness. In a pioneering study, we use resting-state functional near-infrared spectroscopy to predict speech-understanding outcomes before and after CI implantation.
View Article and Find Full Text PDFJAMA Otolaryngol Head Neck Surg
December 2024
Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, Nashville, Tennessee.
Importance: Speech recognition outcomes with a cochlear implant (CI) are highly variable. One factor suggested to correlate with CI-aided speech recognition is frequency-to-place mismatch, or the discrepancy between the natural tonotopic organization of the cochlea and the electric frequency allocation of the CI electrodes within the patient's cochlea.
Objective: To evaluate the association between frequency-to-place mismatch and speech recognition outcomes in a large cohort of postlingually deafened adult CI users, while controlling for various clinical factors known to be associated with those outcomes.
J Neurosci
December 2024
Dept. Biological Sciences, University at Buffalo, State University of New York, Buffalo, NY 14260
The mammalian auditory system encodes sounds with subtypes of spiral ganglion neurons (SGNs) that differ in sound level sensitivity, permitting discrimination across a wide range of levels. Recent work suggests the physiologically-defined SGN subtypes correspond to at least three molecular subtypes. It is not known how information from the different subtypes converges within the cochlear nucleus.
View Article and Find Full Text PDFJ Comp Neurol
December 2024
School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
A gene cadre orchestrates the normal development of sensory and non-sensory cells in the inner ear, segregating the cochlea with a distinct tonotopic sound frequency map, similar brain projection, and five vestibular end-organs. However, the role of genes driving the ear development is largely unknown. Here, we show double deletion of the Iroquois homeobox 3 and 5 transcription factors (Irx3/5 DKO) leads to the fusion of the saccule and the cochlear base.
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