scholarly journals Glycinergic synaptic transmission in the cochlear nucleus of mice with normal hearing and age-related hearing loss

2013 ◽  
Vol 110 (8) ◽  
pp. 1848-1859 ◽  
Author(s):  
Ruili Xie (解瑞立) ◽  
Paul B. Manis
Keyword(s):  
Hearing Loss ◽  
Synaptic Transmission ◽  
Cochlear Nucleus ◽  
Brain Slices ◽  
Normal Hearing ◽  
Mouse Strains ◽  
Age Related ◽  
Glycinergic Inhibition ◽  
Age Related Hearing Loss ◽  
Bushy Cells

The principal inhibitory neurotransmitter in the mammalian cochlear nucleus (CN) is glycine. During age-related hearing loss (AHL), glycinergic inhibition becomes weaker in CN. However, it is unclear what aspects of glycinergic transmission are responsible for weaker inhibition with AHL. We examined glycinergic transmission onto bushy cells of the anteroventral CN in normal-hearing CBA/CaJ mice and in DBA/2J mice, a strain that exhibits an early onset AHL. Glycinergic synaptic transmission was examined in brain slices of mice at 10–15 postnatal days old, 20–35 days old, and at 6–7 mo old. Spontaneous inhibitory postsynaptic current (sIPSC) event frequency and amplitude were the same among all three ages in both strains of mice. However, the amplitudes of IPSCs evoked (eIPSC) from stimulating the dorsal CN were smaller, and the failure rate was higher, with increasing age due to decreased quantal content in both mouse strains, independent of hearing status. The coefficient of variation of the eIPSC amplitude also increased with age. The decay time constant (τ) of sIPSCs and eIPSCs were constant in CBA/CaJ mice at all ages, but were significantly slower in DBA/2J mice at postnatal days 20–35, following the onset of AHL, and not at earlier or later ages. Our results suggest that glycinergic inhibition at the synapses onto bushy cells becomes weaker and less reliable with age through changes in release. However, the hearing loss in DBA/2J mice is accompanied by a transiently enhanced inhibition, which could disrupt the balance of excitation and inhibition.

scholarly journals Synaptic Transmission at the Cochlear Nucleus Endbulb Synapse During Age-Related Hearing Loss in Mice

2005 ◽  
Vol 94 (3) ◽  
pp. 1814-1824 ◽  
Author(s):  
Yong Wang ◽  
Paul B. Manis
Keyword(s):  
Hearing Loss ◽  
Synaptic Transmission ◽  
Cochlear Nucleus ◽  
Auditory Nerve ◽  
High Frequency ◽  
Nerve Activity ◽  
Synaptic Release ◽  
Endbulb Of Held ◽  
Age Related ◽  
Age Related Hearing Loss

Age-related hearing loss (AHL) typically starts from high-frequency regions of the cochlea and over time invades lower-frequency regions. During this progressive hearing loss, sound-evoked activity in spiral ganglion cells is reduced. DBA mice have an early onset of AHL. In this study, we examined synaptic transmission at the endbulb of Held synapse between auditory nerve fibers and bushy cells in the anterior ventral cochlear nucleus (AVCN). Synaptic transmission in hearing-impaired high-frequency areas of the AVCN was altered in old DBA mice. The spontaneous miniature excitatory postsynaptic current (mEPSC) frequency was substantially reduced (about 60%), and mEPSCs were significantly slower (about 115%) and smaller (about 70%) in high-frequency regions of old (average age 45 days) DBA mice compared with tonotopically matched regions of young (average age 22 days) DBA mice. Moreover, synaptic release probability was about 30% higher in high-frequency regions of young DBA than that in old DBA mice. Auditory nerve–evoked EPSCs showed less rectification in old DBA mice, suggesting recruitment of GluR2 subunits into the AMPA receptor complex. No similar age-related changes in synaptic release or EPSCs were found in age-matched, normal hearing young and old CBA mice. Taken together, our results suggest that auditory nerve activity plays a critical role in maintaining normal synaptic function at the endbulb of Held synapse after the onset of hearing. Auditory nerve activity regulates both presynaptic (release probability) and postsynaptic (receptor composition and kinetics) function at the endbulb synapse after the onset of hearing.

scholarly journals SUBCLINICAL AGE-RELATED HEARING LOSS IS INVERSELY ASSOCIATED WITH DEPRESSIVE SYMPTOMS

2019 ◽  
Vol 3 (Supplement_1) ◽  
pp. S552-S552
Author(s):  
Justin S Golub ◽  
Katharine K Brewster ◽  
Adam Brickman ◽  
Adam Ciarleglio ◽  
José Luchsinger ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Depressive Symptoms ◽  
Pure Tone ◽  
Depression Scale ◽  
Pure Tone Audiometry ◽  
Normal Hearing ◽  
Health Study ◽  
Late Life Depression ◽  
Age Related ◽  
Age Related Hearing Loss

Abstract Age-related hearing loss (HL), defined by a pure-tone average (PTA) >25 decibels (dB) has been associated with depressive symptoms. We aimed to assess whether this association is present when hearing is better than the arbitrary, but widely-used, 25 dB threshold. The sampled population was the multicentered Hispanic Community Health Study (n=5,165). Cross-sectional data from 2008-2011 were available. Hearing was measured with pure tone audiometry. Clinically-significant depressive symptoms (CSDS) were defined by a score ≥10 on the 10-item Center for Epidemiologic Studies Depression Scale (CESD-10). Participants’ mean age was 58.3 years (SD=6.2, range=50-76). Among those with classically-defined normal hearing (PTA ≤25 dB), a 10 dB increase in HL was associated with 1.26 times the odds (95% CI=1.11, 1.42) of CSDS, adjusting for age, gender, education, vascular disease, and hearing aid use (p25 dB; p<0.001). Results held even for a stricter HL cutpoint of 15 dB. Among subjects with strictly normal hearing (PTA ≤15 dB), a 10 dB increase in HL was associated with 1.47 (1.14, 1.90) times the odds of CSDS, adjusting for confounders (p<0.01). Results also held when defining CSDS by an alternative CESD-10 score ≥16. In conclusion, increasing hearing thresholds were independently associated with CSDS among adults with subclinical HL (PTA ≤25 dB). Studies investigating whether treating HL can prevent late life depression should consider a lower threshold for defining HL.

scholarly journals D-Stellate Neurons of the Ventral Cochlear Nucleus Decrease in Auditory Nerve-Evoked Activity during Age-Related Hearing Loss

2019 ◽  
Vol 9 (11) ◽  
pp. 302
Author(s):  
Yong Wang ◽  
Meijian Wang ◽  
Ruili Xie
Keyword(s):  
Hearing Loss ◽  
Cochlear Nucleus ◽  
Auditory Nerve ◽  
Inhibitory Neurons ◽  
Membrane Properties ◽  
Patch Clamp Technique ◽  
Age Related ◽  
Underlying Mechanisms ◽  
Age Related Hearing Loss ◽  
Intrinsic Membrane Properties

Age-related hearing loss (ARHL) is associated with weakened inhibition in the central auditory nervous system including the cochlear nucleus. One of the main inhibitory neurons of the cochlear nucleus is the D-stellate neuron, which provides extensive glycinergic inhibition within the local neural network. It remains unclear how physiological activities of D-stellate neurons change during ARHL and what are the underlying mechanisms. Using in vitro whole-cell patch clamp technique, we studied the intrinsic membrane properties of D-stellate neurons, the changes of their firing properties, and the underlying mechanisms in CBA/CaJ mice at the ages of 3–4 months (young), 17–19 months (middle age), and 27–33 months (aged). We found that the intrinsic membrane properties of D-stellate neurons were unchanged among these three age groups. However, these neurons showed decreased firing rate with age in response to sustained auditory nerve stimulation. Further investigation showed that auditory nerve-evoked excitatory postsynaptic currents (EPSCs) were significantly reduced in strength with age. These findings suggest that D-stellate neurons receive weakened synaptic inputs from the auditory nerve and decreased sound driven activity with age, which are expected to reduce the overall inhibition and enhance the central gain in the cochlear nucleus during ARHL.

scholarly journals No association between age-related hearing loss and accelerated brain aging derived from structural neuroimaging data

2020 ◽  
Author(s):  
Stephanie Rosemann ◽  
Christiane Thiel
Keyword(s):  
Hearing Loss ◽  
Brain Aging ◽  
Normal Hearing ◽  
Chronological Age ◽  
Listening Effort ◽  
Structural Neuroimaging ◽  
Age Related ◽  
Neuroimaging Data ◽  
Age Related Hearing Loss ◽  
Brain Age

Aging affects the brain’s underlying biophysical structure as well as its’ cellular and molecular functioning. Brain aging varies largely across individuals and is accelerated in a variety of disease states. Age-related hearing loss affects a large part of the older population and has been shown to impact cognition, brain structure and function. The main aim of this study was to investigate whether age-related hearing loss accelerates brain aging and is related to a decrease in cognitive function and increase in daily listening effort. We used structural neuroimaging data from a large sample of elderly subjects (n=163) with mild to moderate uncompensated age-related hearing loss or normal hearing. An established machine learning approach was applied to predict brain age from grey and white matter maps. Predicted brain age and chronological age significantly correlated across all participants. However, the difference between the predicted brain age and chronological age was neither significantly different between hard of hearing and normal-hearing participants, nor was this age difference significantly associated with general cognitive status or daily life listening effort. We conclude that uncompensated mild to moderate age-related hearing loss has negligible effects on brain age derived from structural neuroimaging data.

scholarly journals The Role of Eye Color in the Emergence of Tinnitus in Silence

2021 ◽  
Author(s):  
Onyinyechi C. Ukaegbe ◽  
Denise A. Tucker
Keyword(s):  
Hearing Loss ◽  
African Americans ◽  
Cross Section ◽  
Auditory Stimulation ◽  
Normal Hearing ◽  
Noise Trauma ◽  
Eye Color ◽  
Age Related ◽  
Age Related Hearing Loss

Abstract Introduction Previous research suggests that African Americans are less likely than Caucasians to perceive tinnitus in sustained silence. Objective To evaluate the association between non-cutaneous melanin as indicated by eye color and the emergence of temporary tinnitus during a brief period of silence. Methods A cross-section of adults grouped according to their eye color were exposed to silence. A total of 62 adults, aged 18 to 35 years (10 males, 52 females) were required to sit in silence for 10 minutes, after which they filled out a questionnaire to report their eye color and any perception of sounds in the ears or head. Results In total, 63% of the participants perceived tinnitus while sitting in silence, and, of these 95% perceived the tinnitus sounds within 5 minutes of sitting in silence. Though African Americans were less likely to perceive tinnitus in silence, this difference was not significant (p = 0.6). After a period of silence, 69% of the subjects with light-colored eyes and 58% of the dark-eyed subjects perceived tinnitus. This difference was not statistically significant (χ2(1) = 0.77; p = 0.38). Conclusion When exposed to reduced auditory stimulation, 3 out of 5 normal-hearing people are likely to experience tinnitus. However, there was no relationship between eye color and the perception of tinnitus in silence. Although melanin has been shown to play a role in the protection of the ear against noise trauma and the effects of age-related hearing loss, its role in the emergence of tinnitus needs further investigation.

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