Regional Specification of Threshold Sensitivity and Response Time in CBA/CaJ Mouse Spiral Ganglion Neurons

2007 ◽  
Vol 98 (4) ◽  
pp. 2215-2222 ◽  
Author(s):  
Qing Liu ◽  
Robin L. Davis
Keyword(s):  
Spiral Ganglion ◽  
Positional Information ◽  
Spike Timing ◽  
Spiral Ganglion Neuron ◽  
Spiral Ganglion Neurons ◽  
Threshold Levels ◽  
Wide Range ◽  
Acoustic Processing ◽  
Neuron Electrophysiology ◽  
Ganglion Neurons

Previous studies of spiral ganglion neuron electrophysiology have shown that specific parameters differ according to cochlear location, with apical neurons being distinctly different from basal neurons. To align these features more precisely along the tonotopic axis of the cochlea, we developed a novel spiral ganglion culture system in which positional information is retained. Patch-clamp recordings made from neurons of known gangliotopic location revealed two basic firing pattern distributions. Membrane characteristics related to spike timing, such as accommodation, latency and onset tau, were distinctly heterogeneous, yet when averaged, they were distributed in a graded manner along the length of the cochlea. Action potential threshold levels also displayed a wide range, the averages of which were distributed nonmonotonically such that neurons with the greatest sensitivity were localized to the mid-regions of the ganglion. These studies shed new light on the complexity and sophistication of the intrinsic firing features of spiral ganglion neurons. Because timing-related elements are organized in an overall tonotopic manner, it is hypothesized that they contribute to aspects of frequency-dependent acoustic processing. On the other hand, the different distribution of threshold levels, with the greatest sensitivity in the middle region of the tonotopic map, suggests that this neuronal parameter is regulated differently and thus may contribute a distinct realm of auditory sensory processing.

scholarly journals Ouabain-Induced Apoptosis in Cochlear Hair Cells and Spiral Ganglion NeuronsIn Vitro

2013 ◽  
Vol 2013 ◽  
pp. 1-16 ◽  
Author(s):  
Yong Fu ◽  
Dalian Ding ◽  
Lei Wei ◽  
Haiyan Jiang ◽  
Richard Salvi
Keyword(s):  
Hair Cells ◽  
Gene Array ◽  
Spiral Ganglion ◽  
Spiral Ganglion Neuron ◽  
Round Window Membrane ◽  
Spiral Ganglion Neurons ◽  
Cochlear Hair Cells ◽  
Ganglion Neurons

Ouabain is a common tool to explore the pathophysiological changes in adult mammalian cochleain vivo. In prior studies, locally administering ouabain via round window membrane demonstrated that the ototoxic effects of ouabainin vivovaried among mammalian species. Little is known about the ototoxic effectsin vitro. Thus, we prepared cochlear organotypic cultures from postnatal day-3 rats and treated these cultures with ouabain at 50, 500, and 1000 μM for different time to elucidate the ototoxic effects of ouabainin vitroand to provide insights that could explain the comparative ototoxic effects of ouabainin vivo. Degeneration of cochlear hair cells and spiral ganglion neurons was evaluated by hair-cell staining and neurofilament labeling, respectively. Annexin V staining was used to detect apoptotic cells. A quantitative RT-PCR apoptosis-focused gene array determined changes in apoptosis-related genes. The results showed that ouabain-induced damagein vitrowas dose and time dependent. 500 μM ouabain and 1000 μM ouabain were destructively traumatic to both spiral ganglion neurons and cochlear hair cells in an apoptotic signal-dependent pathway. The major apoptotic pathways in ouabain-induced spiral ganglion neuron apoptosis culminated in the stimulation of the p53 pathway and triggering of apoptosis by a network of proapoptotic signaling pathways.

scholarly journals The Influence of Cochlear Implant-Based Electric Stimulation on the Electrophysiological Characteristics of Cultured Spiral Ganglion Neurons

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Na Shen ◽  
Lei Zhou ◽  
Bin Lai ◽  
Shufeng Li
Keyword(s):  
Electrical Stimulation ◽  
Cochlear Implant ◽  
Spiral Ganglion ◽  
Reversal Potential ◽  
Neurite Growth ◽  
Spiral Ganglion Neuron ◽  
Spiral Ganglion Neurons ◽  
Vitro Model ◽  
Ganglion Neurons

Background. Cochlear implant-based electrical stimulation may be an important reason to induce the residual hearing loss after cochlear implantation. In our previous study, we found that charge-balanced biphasic electrical stimulation inhibited the neurite growth of spiral ganglion neurons (SGNs) and decreased Schwann cell density in vitro. In this study, we want to know whether cochlear implant-based electrical stimulation can induce the change of electrical activity in cultured SGNs. Methods. Spiral ganglion neuron electrical stimulation in vitro model is established using the devices delivering cochlear implant-based electrical stimulation. After 48 h treatment by 50 μA or 100 μA electrical stimulation, the action potential (AP) and voltage depended calcium current (ICa) of SGNs are recorded using whole-cell electrophysiological method. Results. The results show that the ICa of SGNs is decreased significantly in 50 μA and 100 μA electrical stimulation groups. The reversal potential of ICa is nearly +80 mV in control SGN, but the reversal potential decreases to +50 mV in 50 μA and 100 μA electrical stimulation groups. Interestingly, the AP amplitude, the AP latency, and the AP duration of SGNs have no statistically significant differences in all three groups. Conclusion. Our study suggests cochlear implant-based electrical stimulation only significantly inhibit the ICa of cultured SGNs but has no effect on the firing of AP, and the relation of ICa inhibition and SGN damage induced by electrical stimulation and its mechanism needs to be further studied.

scholarly journals Minocycline Protection of Neomycin Induced Hearing Loss in Gerbils

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Alan M. Robinson ◽  
Irena Vujanovic ◽  
Claus-Peter Richter
Keyword(s):  
Hearing Loss ◽  
Spiral Ganglion ◽  
Hearing Threshold ◽  
Organ Of Corti ◽  
Aminoglycoside Antibiotic ◽  
Histological Evaluation ◽  
Spiral Ganglion Neuron ◽  
Spiral Ganglion Neurons ◽  
Simultaneous Application ◽  
Ganglion Neurons

This animal study was designed to determine if minocycline ameliorates cochlear damage is caused by intratympanic injection of the ototoxic aminoglycoside antibiotic neomycin. Baseline auditory-evoked brainstem responses were measured in gerbils that received 40 mM intratympanic neomycin either with 0, 1.2, or 1.5 mg/kg intraperitoneal minocycline. Four weeks later auditory-evoked brainstem responses were measured and compared to the baseline measurements. Minocycline treatments of 1.2 mg/kg and 1.5 mg/kg resulted in significantly lower threshold increases compared to 0 mg/kg, indicating protection of hearing loss between 6 kHz and 19 kHz. Cochleae were processed for histology and sectioned to allow quantification of the spiral ganglion neurons and histological evaluation of organ of Corti. Significant reduction of spiral ganglion neuron density was demonstrated in animals that did not receive minocycline, indicating that those receiving minocycline demonstrated enhanced survival of spiral ganglion neurons, enhanced survival of sensory hairs cells and spiral ganglion neurons, and reduced hearing threshold elevation correlates with minocycline treatment demonstrating that neomycin induced hearing loss can be reduced by the simultaneous application of minocycline.

TGF-beta superfamily member activin A acts with BDNF and erythropoietin to improve survival of spiral ganglion neurons in vitro

2013 ◽  
Vol 75 ◽  
pp. 416-425 ◽  
Author(s):  
Odett Kaiser ◽  
Gerrit Paasche ◽  
Timo Stöver ◽  
Stefanie Ernst ◽  
Thomas Lenarz ◽  
...  
Keyword(s):  
Spiral Ganglion ◽  
Activin A ◽  
Spiral Ganglion Neurons ◽  
Tgf Beta ◽  
Ganglion Neurons
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