scholarly journals Degradation of Temporal Resolution in the Auditory Midbrain After Prolonged Deafness Is Reversed by Electrical Stimulation of the Cochlea

2005 ◽  
Vol 93 (6) ◽  
pp. 3339-3355 ◽  
Author(s):  
Maike Vollmer ◽  
Patricia A. Leake ◽  
Ralph E. Beitel ◽  
Stephen J. Rebscher ◽  
Russell L. Snyder
Keyword(s):  
Electrical Stimulation ◽  
Auditory System ◽  
Temporal Resolution ◽  
Central Nucleus ◽  
Central Auditory System ◽  
Auditory Midbrain ◽  
Chronic Stimulation ◽  
Spiral Ganglion Cell ◽  
Chronic Electrical Stimulation

In an animal model of prelingual deafness, we examined the anatomical and physiological effects of prolonged deafness and chronic electrical stimulation on temporal resolution in the adult central auditory system. Maximum following frequencies ( Fmax) and first spike latencies of single neurons responding to electrical pulse trains were evaluated in the inferior colliculus of two groups of neonatally deafened cats after prolonged periods of deafness (>2.5 yr): the first group was implanted with an intracochlear electrode and studied acutely (long-deafened unstimulated, LDU); the second group (LDS) received a chronic implant and several weeks of electrical stimulation (pulse rates ≥300 pps). Acutely deafened and implanted adult cats served as controls. Spiral ganglion cell density in all long-deafened animals was markedly reduced (mean <5.8% of normal). Both long-term deafness and chronic electrical stimulation altered temporal resolution of neurons in the central nucleus (ICC) but not in the external nucleus. Specifically, LDU animals exhibited significantly poorer temporal resolution of ICC neurons (lower Fmax, longer response latencies) as compared with control animals. In contrast, chronic stimulation in LDS animals led to a significant increase in temporal resolution. Changes in temporal resolution after long-term deafness and chronic stimulation occurred broadly across the entire ICC and were not correlated with its tonotopic gradient. These results indicate that chronic electrical stimulation can reverse the degradation in temporal resolution in the auditory midbrain after long-term deafness and suggest the importance of factors other than peripheral pathology on plastic changes in the temporal processing capabilities of the central auditory system.

scholarly journals Amino acid concentrations in the hamster central auditory system and long-term effects of intense tone exposure

2012 ◽  
Vol 90 (11) ◽  
pp. 2214-2224 ◽  
Author(s):  
Donald A. Godfrey ◽  
James A. Kaltenbach ◽  
Kejian Chen ◽  
Omer Ilyas ◽  
Xiaochen Liu ◽  
...  
Keyword(s):  
Amino Acid ◽  
Auditory System ◽  
Central Auditory System ◽  
Long Term Effects ◽  
Amino Acid Concentrations

Temporal resolution of neurons in cat inferior colliculus to intracochlear electrical stimulation: effects of neonatal deafening and chronic stimulation

1995 ◽  
Vol 73 (2) ◽  
pp. 449-467 ◽  
Author(s):  
R. Snyder ◽  
P. Leake ◽  
S. Rebscher ◽  
R. Beitel
Keyword(s):  
Electrical Stimulation ◽  
Inferior Colliculus ◽  
Temporal Resolution ◽  
Transfer Functions ◽  
Discharge Rate ◽  
Pulse Frequency ◽  
Acoustic Stimulation ◽  
Acute Experiment ◽  
Sustained Response ◽  
Central Nucleus

1. Cochlear implants have been available for > 20 yr to profoundly deaf adults who have lost their hearing after acquiring language. The success of these cochlear prostheses has encouraged the application of implants in prelingually deaf children as young as 2 yr old. To further characterize the consequences of chronic intracochlear electrical stimulation (ICES) on the developing auditory system, the temporal-response properties of single neurons in the inferior colliculus (IC) were recorded in deafened anesthetized cats. 2. The neurons were excited by unilateral ICES with the use of a scala tympani stimulating electrode implanted in the left cochlea. The electrodes were modeled after those used in cochlear implant patients. Responses of 443 units were recorded extracellularly in the contralateral (right) IC with the use of tungsten microelectrodes. Recordings were made in three groups of adult animals: neonatally deafened/chronically stimulated animals (192 units), neonatally deafened/unstimulated animals (80 units), and adult-deafened/prior normal-hearing animals (171 units). The neonatally deafened cats were deafened by multiple intramuscular injections of neomycin sulfate and never developed demonstrable hearing. Most of the deafened, chronically stimulated animals were implanted at 6 wk of age and stimulated at suprathreshold levels for 4 h/day for 3-6 mo. The unstimulated animals were implanted as adults at least 2 wk before the acute physiological experiment and were left unstimulated until the acute experiment was conducted. Prior-normal adults were deafened and implanted at least 2 wk before the acute experiment. 3. IC units were isolated with the use of a search stimulus consisting of three cycles of a 100-Hz sinusoid. Most units responded to sinusoidal stimulation with either an onset response or a sustained response. Onset units were the predominant unit found in the external nucleus, whereas sustained units were found almost exclusively in the central nucleus. The temporal resolution of sustained response units was measured with the use of pulse trains of increasing frequency and calculating the discharges/pulse. 4. The range of electrical pulse frequencies to which IC units responded in a temporally synchronized manner was comparable with that produced by acoustic stimulation. The discharge rate/pulse-versus-pulse frequency transfer functions of IC units were uniformly low-pass, although they varied widely in their cutoff frequencies. This variation in pulse response was partially correlated with the unit's response to sinusoids. Most onset neurons responded only to pulse frequencies below 20 pulses per second (pps). Most sustained units responded best to pulse frequencies < 100 pps, and most ceased to respond to pulse frequencies > 300 pps.(ABSTRACT TRUNCATED AT 400 WORDS)

Chronic electrical stimulation does not prevent spiral ganglion cell degeneration in deafened guinea pigs

2010 ◽  
Vol 269 (1-2) ◽  
pp. 169-179 ◽  
Author(s):  
Martijn J.H. Agterberg ◽  
Huib Versnel ◽  
John C.M.J. de Groot ◽  
Marloes van den Broek ◽  
Sjaak F.L. Klis
Keyword(s):  
Electrical Stimulation ◽  
Ganglion Cell ◽  
Guinea Pigs ◽  
Spiral Ganglion ◽  
Cell Degeneration ◽  
Spiral Ganglion Cell ◽  
Chronic Electrical Stimulation

scholarly journals A systematic review of mercury ototoxicity

2012 ◽  
Vol 28 (7) ◽  
pp. 1239-1248 ◽  
Author(s):  
Ana Cristina Hiromi Hoshino ◽  
Heloisa Pacheco Ferreira ◽  
Olaf Malm ◽  
Renata Mamede Carvallo ◽  
Volney Magalhães Câmara
Keyword(s):  
Systematic Review ◽  
Auditory System ◽  
Chemical Substance ◽  
Mercury Exposure ◽  
Central Auditory System ◽  
Inclusion Criteria ◽  
Irreversible Damage ◽  
The Relationship

Mercury is neurotoxic, and numerous studies have confirmed its ototoxic effect. However, the diagnosis and follow-up of mercury exposure require understanding the pathophysiology of the chemical substance. Based on a systematic literature review, this study aimed to demonstrate whether mercury is ototoxic and to analyze its mechanism of action on the peripheral and central auditory system, in order to contribute to the diagnosis and follow-up of exposure. This was a systematic review of studies published on the effects of mercury exposure on the auditory system. The full text of the studies and their methodological quality were analyzed. The review identified 108 studies published on the theme, of which 28 met the inclusion criteria. All the articles in the analysis showed that mercury exposure is ototoxic and produces peripheral and/or central damage. Acute and long-term exposure produces irreversible damage to the central auditory system. Biomarkers were unable to predict the relationship between degree of mercury poisoning and degree of lesion in the auditory system.

AUDITORY REHABILITATION AFTER LONG-TERM DEAFNESS

Neurosurgery ◽  
2008 ◽  
Vol 62 (4) ◽  
pp. 983-986 ◽  
Author(s):  
Alireza Gharabaghi ◽  
Hubert Löwenheim ◽  
Stefan Heckl ◽  
Andrei Koerbel ◽  
Jan Kaminsky ◽  
...  
Keyword(s):  
Auditory System ◽  
Auditory Perception ◽  
Auditory Brainstem ◽  
Central Auditory System ◽  
Auditory Rehabilitation ◽  
Lack Of Information ◽  
Profound Deafness ◽  
Spectral Patterns ◽  
Cranial Nerve Viii

Abstract OBJECTIVE The duration of preexisting profound deafness in patients with bilateral retrocochlear lesions is known to correlate negatively to the extent of auditory restoration after auditory brainstem implantation. There is, therefore, a lack of information regarding the potential of the central auditory system to mediate hearing perception after long-term deafness. METHODS The authors evaluated auditory perception in a case of auditory brainstem implantation after 35 years of deafness. RESULTS Electrically evoked auditory brainstem potentials could be elicited by both stimulus polarities and were consistent with auditory brainstem origin. Discrimination between temporal and spectral patterns in speech could be achieved. This permitted us to distinguish various voice qualities, especially of familiar speakers in quiet surroundings. CONCLUSION The potential of the deafferentiated central auditory system to mediate auditory brainstem implant-induced hearing perception even after very long-term deafness has been demonstrated. Those patients with complete dysfunction of Cranial Nerve VIII for a long period may be considered as candidates for auditory brainstem implantation in the future.

Sign in / Sign up

Export Citation Format

Share Document