Jean-marie Aran - Academia.edu (original) (raw)
Papers by Jean-marie Aran
Acta Oto-laryngologica, 1973
Les premiers resultats d'une serie d'experimentations visant a reproduire chez l'anim... more Les premiers resultats d'une serie d'experimentations visant a reproduire chez l'animal les differents types de responses du nerf auditif observes dans la pathologie humaine sont rapportes. 5 cobayes equipe d'une electrode a demeure sur la fenětre ronde (oreille gauche) ont ete soumis a des traumatismes sonores (bruit blanc 110 dB) repetes (6 fois 6 heures). L'evolution des responses du nerf auditif au clic et aux differents clics filtres est observee en enregistrant regulierement avant pendant et apres la serie de traumatismes. Le microphonique cochleaire est egalement mesure au debut et a la fin de I'experimentation. Au moins 5 semaines apres le dernier traumatisme des enregistrements de controle sont effectues sur les oreilles droites et, apres sacrifice du cobaye, les organes de Corti des cochlees droite et gauche sont observes en microscopie a contraste de phase (surface preparations). Chez les 5 cobayes on observe, a la iin de l'experimentation, des reponses du nerf auditif en tout point comparables...
Acta Oto-laryngologica, 1973
Les premiers resultats d'une serie d'experimentations visant a reproduire chez l'anim... more Les premiers resultats d'une serie d'experimentations visant a reproduire chez l'animal les differents types de responses du nerf auditif observes dans la pathologie humaine sont rapportes. 5 cobayes equipe d'une electrode a demeure sur la fenětre ronde (oreille gauche) ont ete soumis a des traumatismes sonores (bruit blanc 110 dB) repetes (6 fois 6 heures). L'evolution des responses du nerf auditif au clic et aux differents clics filtres est observee en enregistrant regulierement avant pendant et apres la serie de traumatismes. Le microphonique cochleaire est egalement mesure au debut et a la fin de I'experimentation. Au moins 5 semaines apres le dernier traumatisme des enregistrements de controle sont effectues sur les oreilles droites et, apres sacrifice du cobaye, les organes de Corti des cochlees droite et gauche sont observes en microscopie a contraste de phase (surface preparations). Chez les 5 cobayes on observe, a la iin de l'experimentation, des reponses du nerf auditif en tout point comparables...
ORL, 1994
Functional and morphological alterations were compared in guinea pig cochleae treated acutely (7.... more Functional and morphological alterations were compared in guinea pig cochleae treated acutely (7.5 mg/kg x 2) and chronically (1.5 mg/kg x 10) with cisplatin. Drastic and rapid hearing impairments using compound action potential were observed only after the second injection during acute treatment. During chronic treatment, threshold changes were observed abruptly after 8 or 9 days of treatment. Morphological changes of outer hair cells were stronger in the acute treatment than the chronic one, and they appeared to concur with the functional data. Partial damage in the stria vascularis was observed only after acute treatment. From these results, it was suspected that acute and chronic ototoxic mechanisms differed according to the pharmacokinetics of cisplatin in the inner ear fluid and tissues.
ORL, 1994
Functional and morphological alterations were compared in guinea pig cochleae treated acutely (7.... more Functional and morphological alterations were compared in guinea pig cochleae treated acutely (7.5 mg/kg x 2) and chronically (1.5 mg/kg x 10) with cisplatin. Drastic and rapid hearing impairments using compound action potential were observed only after the second injection during acute treatment. During chronic treatment, threshold changes were observed abruptly after 8 or 9 days of treatment. Morphological changes of outer hair cells were stronger in the acute treatment than the chronic one, and they appeared to concur with the functional data. Partial damage in the stria vascularis was observed only after acute treatment. From these results, it was suspected that acute and chronic ototoxic mechanisms differed according to the pharmacokinetics of cisplatin in the inner ear fluid and tissues.
Journal of the Acoustical Society of America, Feb 1, 1983
An experimental study of the electrical stimulation of the guinea pig cochlea is made using an el... more An experimental study of the electrical stimulation of the guinea pig cochlea is made using an electrode on the round window for both stimulation and recording. The neural response is separated from the electrical artifact with a masking procedure combined with a low amplification, "statistical" averaging method [Charlet de Sauvage et al., Hear. Res. 2, 343-346 (1980)]. The high electrical impedance required for recording physiological responses implies the use of a current pulse generator. Monitoring of evoked potentials from the auditory cortex provides evidence that the effects of electrical stimulation (and of masking noise) are of auditory origin. The electrically evoked round window response is of very short latency (less than 0.2 ms). There is a response threshold for both electrical stimulus and masking noise. The response amplitude varies monotonically as a function of masking noise or electrical stimulus intensity. Experiments with high-pass noise masking suggest that the electrical stimulus is mainly acting on basal fibers. The response latency and waveform are independent of electrical stimulus intensity, ß repetition rate, masker level, or spectrum. Little intersubject variation is noted. Our experiments (reciprocal forward masking by electrical and acoustic stimuli) suggest that a direct, instantaneous electrical stimulation of the fibers occurs. We believe that this response to electrical stimulation represents the mean unit response of the auditory ne•e fibers. This approach may be useful in the separate study of cochlear and VIIIth nerve functions and in the analysis (deconvolution) of the-acoustically evoked compound AP.
Journal of the Acoustical Society of America, Feb 1, 1983
An experimental study of the electrical stimulation of the guinea pig cochlea is made using an el... more An experimental study of the electrical stimulation of the guinea pig cochlea is made using an electrode on the round window for both stimulation and recording. The neural response is separated from the electrical artifact with a masking procedure combined with a low amplification, "statistical" averaging method [Charlet de Sauvage et al., Hear. Res. 2, 343-346 (1980)]. The high electrical impedance required for recording physiological responses implies the use of a current pulse generator. Monitoring of evoked potentials from the auditory cortex provides evidence that the effects of electrical stimulation (and of masking noise) are of auditory origin. The electrically evoked round window response is of very short latency (less than 0.2 ms). There is a response threshold for both electrical stimulus and masking noise. The response amplitude varies monotonically as a function of masking noise or electrical stimulus intensity. Experiments with high-pass noise masking suggest that the electrical stimulus is mainly acting on basal fibers. The response latency and waveform are independent of electrical stimulus intensity, ß repetition rate, masker level, or spectrum. Little intersubject variation is noted. Our experiments (reciprocal forward masking by electrical and acoustic stimuli) suggest that a direct, instantaneous electrical stimulation of the fibers occurs. We believe that this response to electrical stimulation represents the mean unit response of the auditory ne•e fibers. This approach may be useful in the separate study of cochlear and VIIIth nerve functions and in the analysis (deconvolution) of the-acoustically evoked compound AP.
Annals of Otology, Rhinology, and Laryngology, Nov 1, 1983
The possibility of stimulating the ear by way of an electrode on the round window in order to rel... more The possibility of stimulating the ear by way of an electrode on the round window in order to relieve tinnitus or to produce auditory sensations has been investigated experimentally in guinea pigs. The deleterious effects of DC currents applied to a normal cochlea clearly demonstrate that this means is unsuitable for use in relieving tinnitus in hearing patients. Although AC currents do not cause further damage in ears with the organ of Corti already destroyed by aminoglycosides, the effects of DC currents in such cases have still to be in vestigated before they can be recommended for the relief of tinnitus in totally deaf patients. Electrical stimulation of the round window combined with masking has made it possible to record responses of auditory neural elements from the eighth nerve to the auditory cortex. This technique could be promising for the basic study of the central auditory nervous system, both experimentally and clinically, and could lead to a more accurate evaluation of candidates for cochlear prostheses. ..uic.v.v^... ..w.., times during the stimulation, bringing about defi-From the Clinique Universitaire d'ORL et Laboratoire d'Audiologie Experimentale. Bordeaux. France. This work was supported hy grants from the Delegation Generate a la Recherche Scientifique et Technique (8I-P-U00) and from the Elablissenient Public Regional (Genie Bio-Medical-Audiologic. 1982).
Annals of Otology, Rhinology, and Laryngology, Nov 1, 1983
The possibility of stimulating the ear by way of an electrode on the round window in order to rel... more The possibility of stimulating the ear by way of an electrode on the round window in order to relieve tinnitus or to produce auditory sensations has been investigated experimentally in guinea pigs. The deleterious effects of DC currents applied to a normal cochlea clearly demonstrate that this means is unsuitable for use in relieving tinnitus in hearing patients. Although AC currents do not cause further damage in ears with the organ of Corti already destroyed by aminoglycosides, the effects of DC currents in such cases have still to be in vestigated before they can be recommended for the relief of tinnitus in totally deaf patients. Electrical stimulation of the round window combined with masking has made it possible to record responses of auditory neural elements from the eighth nerve to the auditory cortex. This technique could be promising for the basic study of the central auditory nervous system, both experimentally and clinically, and could lead to a more accurate evaluation of candidates for cochlear prostheses. ..uic.v.v^... ..w.., times during the stimulation, bringing about defi-From the Clinique Universitaire d'ORL et Laboratoire d'Audiologie Experimentale. Bordeaux. France. This work was supported hy grants from the Delegation Generate a la Recherche Scientifique et Technique (8I-P-U00) and from the Elablissenient Public Regional (Genie Bio-Medical-Audiologic. 1982).
European Archives of Oto-rhino-laryngology, 1979
Electrophysiological and histological observations in guinea pig's cochleas after amikacin treatm... more Electrophysiological and histological observations in guinea pig's cochleas after amikacin treatment (14 x 450 mg/kg) confirm the results obtained in a former experiment: clear, short-latency, click-evoked responses were recorded in cochleas with only very few hair cells remaining at the extreme apex. Detailed analysis of these responses strongly indicates a neural origin and confirms their low-frequency sensitivity. Careful histological observations confirm the extensive hair cell loss and the preservation of nerve fibers in the remnants of the organ of Corti and of the vestibular sense organs. These results suggest that the acoustical vibrations either stimulate the vestibular receptors or act directly or through some kind of mechano-electrical transduction on the remaining cochlear nerve fibers.
Hearing Research, Aug 1, 1997
In the electrical stimulation (ES) of auditory pathways, the type of stimulus and the electrode/t... more In the electrical stimulation (ES) of auditory pathways, the type of stimulus and the electrode/tissue interface are critical parameters for the safety and efficacy of the protocol. In this study the influence of alternate pulses, applied between round window and vertex electrodes in chronically implanted guinea pigs, and maintained during 1 and 25 daily periods of 2 h (short-term and long-term experiments, respectively), was investigated. ES consisted of monophasic current pulses of +/- 70 microA and 300 (micro)s in duration at a rate of 167/s, with alternate polarity. Compound Action Potential (CAP) audiograms, amplitudes and latencies of click-evoked CAPs, amplitudes and latencies of electrically-evoked auditory responses (EARs), and electrode impedances, were measured periodically outside or during the ES periods. Short-term ES induced no change in CAP thresholds, amplitude and latency in response to clicks at 80 dB above normal threshold, but induced a slight latency increase and amplitude decrease of the EAR, correlated with an exponential decay of the electrode impedance. On a long-term basis, CAP audiograms and latencies did not change significantly, whereas CAP amplitudes and electrode impedances increased, in correlation with each other. In control guinea pigs receiving no ES, the same CAP amplitude and impedance changes were observed over the same long-term period. The EAR and CAP changes can be explained by a variation of the electrical impedance of the electrode/tissue interface. This is possibly due to a change in electrolytes around the electrode under the influence of the ES for the short-term variation, and to an electrode encapsulation by fibrous tissue independent of the ES for the long-term change. In itself, and under the conditions of this experiment, the ES demonstrated no adverse effects on the auditory function and can be safely used for inner-ear exploration.
Acta Oto-laryngologica, 1980
A series of patients presenting with subsequently surgically confirmed central tumour involving t... more A series of patients presenting with subsequently surgically confirmed central tumour involving the auditory pathways were investigated using both transtympanic electrocochleography (TT ECochG) and surface recordings of brainstem evoked responses (BER). While ECochG allows a detailed study of peripheral function, BER allow the investigation of neural conduction up to the level of the inferior colliculus. Valuable information can be obtained from: (1) comparison of the amplitudes of the sensory and neural components of the ECochG; (2) comparison of ECochG, BER and auditory thresholds; (3) time interval measurements between the auditory nerve response (N1 on the ECochG) and the inferior colliculus (wave P4-5 on BER); (4) contralateral comparisons. Similar measurements performed in pure cochlear pathologies, mainly in Meniere's disease, yielded very significant differences.
Archives of oto-rhino-laryngology, Oct 1, 1982
A measure of the (average) rate of discharge versus intensity function of cochlear fibers can be ... more A measure of the (average) rate of discharge versus intensity function of cochlear fibers can be obtained from cochlear-evoked compound action potentials using a tone-on-tone forward masking technique. The rationale for the method is presented. This technique was used to investigate, indirectly, cochlear fiber responses in human subjects, both with normal hearing and with deafness of cochlear origin and showing signs of loudness recruitment. In animals with pathologic cochleas, and change in rate of fiber discharge with intensity is more rapid than in normal animals. The present study confirms that this also is the case in human cochlear pathology and suggests that this abnormal steepening of rate versus intensity functions contributes to the phenomenon of loudness recruitment.
Acta Oto-laryngologica, 1992
Development of the spiral ganglion in white rats was followed during the first 2 weeks after birt... more Development of the spiral ganglion in white rats was followed during the first 2 weeks after birth and morphological characteristics of the two neuronal types (I and II) were examined. In some neurons different stages of partial degeneration leading to formation of residual bodies were found without observation of degenerated cell, supporting the idea that differentiation at this time is not associated with cell death. Contacts between cell body of type II neurons and neuronal endings is reported for the first time. Such axo-somatic contacts previously observed only in monkey and man, also exists in lower mammals.
Archives of oto-rhino-laryngology, Aug 1, 1984
Cochlear action potential thresholds across frequency (AP audiograms) and AP tuning curves were c... more Cochlear action potential thresholds across frequency (AP audiograms) and AP tuning curves were compared in albino (Dunkin-Hartley) guinea pigs and normal pigmented animals. AP audiograms were very similar; on average the albinos had AP thresholds 2-3 dB lower at 2 kHz and below compared with the pigmented guinea pig. AP tuning curves at 16 kHz were, on average, significantly less sharply tuned in the albino, but similar at 8, 4, and 2 kHz. Although we find only small differences in these measures of normal cochlear function, other evidence in the literature suggests that in auditory research the use of "albino" guinea pigs is best avoided.
PubMed, Mar 1, 1978
Sensations induced by electrical stimulation of the cochlea in humans through a promontory or a r... more Sensations induced by electrical stimulation of the cochlea in humans through a promontory or a round window electrode were studied in sixteen subjects. All the patients had total or severe hearing losses. Comparison of the results with the recordings of cochlear potentials gave valuable information in all cases about the site and degree of the disorder. The data on electrically induced auditory sensation are very similar to the general findings of other authors and support the attempts of rehabilitation of the deaf by this means. The most important result reported here is the cancellation of tinnitus during stimulation by positive pulses in most cases, without affecting simultaneous acoustical or electrical hearing. This phenomenon is very reliable and could lead to very important future developments.
Annals of Otology, Rhinology, and Laryngology, Nov 1, 1983
Electrical stimulation of the ear in humans was performed with an extracochlear electrode on the ... more Electrical stimulation of the ear in humans was performed with an extracochlear electrode on the round window. With positive currents, suppression of tinnitus could be induced. With negative currents, auditory sensations were evoked. Since electrical stimulation with DC currents may be hazardous in the long term, it cannot yet be proposed for the suppression of tinnitus. However, electrically evoked hearing sensations with AC currents seem to be of definite interest for some totally deaf patients.
Acta Oto-laryngologica, 1987
An immunohistochemical study was performed on the brainstem of the guinea pig, using a specific a... more An immunohistochemical study was performed on the brainstem of the guinea pig, using a specific antibody against glycine. Glycine-like immunoreactivity was observed in stellate and multipolar neurons in the cochlear nucleus, in the medial and lateral nuclei of the trapezoid body and in the ventromedial periolivary cell group. No immunoreactive neurons were found in the vestibular nuclei. Positive fibre tracts were observed mainly in dorsal acoustic stria and lateral lemniscus. The results are consistent with electrophysiological and anatomical data from the literature concerning the response pattern in the fusiform layer of the dorsal cochlear nucleus and the phenomenon of binaural inhibition in the superior olivary complex.
Acta Oto-laryngologica, 1973
Les premiers resultats d'une serie d'experimentations visant a reproduire chez l'anim... more Les premiers resultats d'une serie d'experimentations visant a reproduire chez l'animal les differents types de responses du nerf auditif observes dans la pathologie humaine sont rapportes. 5 cobayes equipe d'une electrode a demeure sur la fenětre ronde (oreille gauche) ont ete soumis a des traumatismes sonores (bruit blanc 110 dB) repetes (6 fois 6 heures). L'evolution des responses du nerf auditif au clic et aux differents clics filtres est observee en enregistrant regulierement avant pendant et apres la serie de traumatismes. Le microphonique cochleaire est egalement mesure au debut et a la fin de I'experimentation. Au moins 5 semaines apres le dernier traumatisme des enregistrements de controle sont effectues sur les oreilles droites et, apres sacrifice du cobaye, les organes de Corti des cochlees droite et gauche sont observes en microscopie a contraste de phase (surface preparations). Chez les 5 cobayes on observe, a la iin de l'experimentation, des reponses du nerf auditif en tout point comparables...
Acta Oto-laryngologica, 1973
Les premiers resultats d'une serie d'experimentations visant a reproduire chez l'anim... more Les premiers resultats d'une serie d'experimentations visant a reproduire chez l'animal les differents types de responses du nerf auditif observes dans la pathologie humaine sont rapportes. 5 cobayes equipe d'une electrode a demeure sur la fenětre ronde (oreille gauche) ont ete soumis a des traumatismes sonores (bruit blanc 110 dB) repetes (6 fois 6 heures). L'evolution des responses du nerf auditif au clic et aux differents clics filtres est observee en enregistrant regulierement avant pendant et apres la serie de traumatismes. Le microphonique cochleaire est egalement mesure au debut et a la fin de I'experimentation. Au moins 5 semaines apres le dernier traumatisme des enregistrements de controle sont effectues sur les oreilles droites et, apres sacrifice du cobaye, les organes de Corti des cochlees droite et gauche sont observes en microscopie a contraste de phase (surface preparations). Chez les 5 cobayes on observe, a la iin de l'experimentation, des reponses du nerf auditif en tout point comparables...
ORL, 1994
Functional and morphological alterations were compared in guinea pig cochleae treated acutely (7.... more Functional and morphological alterations were compared in guinea pig cochleae treated acutely (7.5 mg/kg x 2) and chronically (1.5 mg/kg x 10) with cisplatin. Drastic and rapid hearing impairments using compound action potential were observed only after the second injection during acute treatment. During chronic treatment, threshold changes were observed abruptly after 8 or 9 days of treatment. Morphological changes of outer hair cells were stronger in the acute treatment than the chronic one, and they appeared to concur with the functional data. Partial damage in the stria vascularis was observed only after acute treatment. From these results, it was suspected that acute and chronic ototoxic mechanisms differed according to the pharmacokinetics of cisplatin in the inner ear fluid and tissues.
ORL, 1994
Functional and morphological alterations were compared in guinea pig cochleae treated acutely (7.... more Functional and morphological alterations were compared in guinea pig cochleae treated acutely (7.5 mg/kg x 2) and chronically (1.5 mg/kg x 10) with cisplatin. Drastic and rapid hearing impairments using compound action potential were observed only after the second injection during acute treatment. During chronic treatment, threshold changes were observed abruptly after 8 or 9 days of treatment. Morphological changes of outer hair cells were stronger in the acute treatment than the chronic one, and they appeared to concur with the functional data. Partial damage in the stria vascularis was observed only after acute treatment. From these results, it was suspected that acute and chronic ototoxic mechanisms differed according to the pharmacokinetics of cisplatin in the inner ear fluid and tissues.
Journal of the Acoustical Society of America, Feb 1, 1983
An experimental study of the electrical stimulation of the guinea pig cochlea is made using an el... more An experimental study of the electrical stimulation of the guinea pig cochlea is made using an electrode on the round window for both stimulation and recording. The neural response is separated from the electrical artifact with a masking procedure combined with a low amplification, "statistical" averaging method [Charlet de Sauvage et al., Hear. Res. 2, 343-346 (1980)]. The high electrical impedance required for recording physiological responses implies the use of a current pulse generator. Monitoring of evoked potentials from the auditory cortex provides evidence that the effects of electrical stimulation (and of masking noise) are of auditory origin. The electrically evoked round window response is of very short latency (less than 0.2 ms). There is a response threshold for both electrical stimulus and masking noise. The response amplitude varies monotonically as a function of masking noise or electrical stimulus intensity. Experiments with high-pass noise masking suggest that the electrical stimulus is mainly acting on basal fibers. The response latency and waveform are independent of electrical stimulus intensity, ß repetition rate, masker level, or spectrum. Little intersubject variation is noted. Our experiments (reciprocal forward masking by electrical and acoustic stimuli) suggest that a direct, instantaneous electrical stimulation of the fibers occurs. We believe that this response to electrical stimulation represents the mean unit response of the auditory ne•e fibers. This approach may be useful in the separate study of cochlear and VIIIth nerve functions and in the analysis (deconvolution) of the-acoustically evoked compound AP.
Journal of the Acoustical Society of America, Feb 1, 1983
An experimental study of the electrical stimulation of the guinea pig cochlea is made using an el... more An experimental study of the electrical stimulation of the guinea pig cochlea is made using an electrode on the round window for both stimulation and recording. The neural response is separated from the electrical artifact with a masking procedure combined with a low amplification, "statistical" averaging method [Charlet de Sauvage et al., Hear. Res. 2, 343-346 (1980)]. The high electrical impedance required for recording physiological responses implies the use of a current pulse generator. Monitoring of evoked potentials from the auditory cortex provides evidence that the effects of electrical stimulation (and of masking noise) are of auditory origin. The electrically evoked round window response is of very short latency (less than 0.2 ms). There is a response threshold for both electrical stimulus and masking noise. The response amplitude varies monotonically as a function of masking noise or electrical stimulus intensity. Experiments with high-pass noise masking suggest that the electrical stimulus is mainly acting on basal fibers. The response latency and waveform are independent of electrical stimulus intensity, ß repetition rate, masker level, or spectrum. Little intersubject variation is noted. Our experiments (reciprocal forward masking by electrical and acoustic stimuli) suggest that a direct, instantaneous electrical stimulation of the fibers occurs. We believe that this response to electrical stimulation represents the mean unit response of the auditory ne•e fibers. This approach may be useful in the separate study of cochlear and VIIIth nerve functions and in the analysis (deconvolution) of the-acoustically evoked compound AP.
Annals of Otology, Rhinology, and Laryngology, Nov 1, 1983
The possibility of stimulating the ear by way of an electrode on the round window in order to rel... more The possibility of stimulating the ear by way of an electrode on the round window in order to relieve tinnitus or to produce auditory sensations has been investigated experimentally in guinea pigs. The deleterious effects of DC currents applied to a normal cochlea clearly demonstrate that this means is unsuitable for use in relieving tinnitus in hearing patients. Although AC currents do not cause further damage in ears with the organ of Corti already destroyed by aminoglycosides, the effects of DC currents in such cases have still to be in vestigated before they can be recommended for the relief of tinnitus in totally deaf patients. Electrical stimulation of the round window combined with masking has made it possible to record responses of auditory neural elements from the eighth nerve to the auditory cortex. This technique could be promising for the basic study of the central auditory nervous system, both experimentally and clinically, and could lead to a more accurate evaluation of candidates for cochlear prostheses. ..uic.v.v^... ..w.., times during the stimulation, bringing about defi-From the Clinique Universitaire d'ORL et Laboratoire d'Audiologie Experimentale. Bordeaux. France. This work was supported hy grants from the Delegation Generate a la Recherche Scientifique et Technique (8I-P-U00) and from the Elablissenient Public Regional (Genie Bio-Medical-Audiologic. 1982).
Annals of Otology, Rhinology, and Laryngology, Nov 1, 1983
The possibility of stimulating the ear by way of an electrode on the round window in order to rel... more The possibility of stimulating the ear by way of an electrode on the round window in order to relieve tinnitus or to produce auditory sensations has been investigated experimentally in guinea pigs. The deleterious effects of DC currents applied to a normal cochlea clearly demonstrate that this means is unsuitable for use in relieving tinnitus in hearing patients. Although AC currents do not cause further damage in ears with the organ of Corti already destroyed by aminoglycosides, the effects of DC currents in such cases have still to be in vestigated before they can be recommended for the relief of tinnitus in totally deaf patients. Electrical stimulation of the round window combined with masking has made it possible to record responses of auditory neural elements from the eighth nerve to the auditory cortex. This technique could be promising for the basic study of the central auditory nervous system, both experimentally and clinically, and could lead to a more accurate evaluation of candidates for cochlear prostheses. ..uic.v.v^... ..w.., times during the stimulation, bringing about defi-From the Clinique Universitaire d'ORL et Laboratoire d'Audiologie Experimentale. Bordeaux. France. This work was supported hy grants from the Delegation Generate a la Recherche Scientifique et Technique (8I-P-U00) and from the Elablissenient Public Regional (Genie Bio-Medical-Audiologic. 1982).
European Archives of Oto-rhino-laryngology, 1979
Electrophysiological and histological observations in guinea pig's cochleas after amikacin treatm... more Electrophysiological and histological observations in guinea pig's cochleas after amikacin treatment (14 x 450 mg/kg) confirm the results obtained in a former experiment: clear, short-latency, click-evoked responses were recorded in cochleas with only very few hair cells remaining at the extreme apex. Detailed analysis of these responses strongly indicates a neural origin and confirms their low-frequency sensitivity. Careful histological observations confirm the extensive hair cell loss and the preservation of nerve fibers in the remnants of the organ of Corti and of the vestibular sense organs. These results suggest that the acoustical vibrations either stimulate the vestibular receptors or act directly or through some kind of mechano-electrical transduction on the remaining cochlear nerve fibers.
Hearing Research, Aug 1, 1997
In the electrical stimulation (ES) of auditory pathways, the type of stimulus and the electrode/t... more In the electrical stimulation (ES) of auditory pathways, the type of stimulus and the electrode/tissue interface are critical parameters for the safety and efficacy of the protocol. In this study the influence of alternate pulses, applied between round window and vertex electrodes in chronically implanted guinea pigs, and maintained during 1 and 25 daily periods of 2 h (short-term and long-term experiments, respectively), was investigated. ES consisted of monophasic current pulses of +/- 70 microA and 300 (micro)s in duration at a rate of 167/s, with alternate polarity. Compound Action Potential (CAP) audiograms, amplitudes and latencies of click-evoked CAPs, amplitudes and latencies of electrically-evoked auditory responses (EARs), and electrode impedances, were measured periodically outside or during the ES periods. Short-term ES induced no change in CAP thresholds, amplitude and latency in response to clicks at 80 dB above normal threshold, but induced a slight latency increase and amplitude decrease of the EAR, correlated with an exponential decay of the electrode impedance. On a long-term basis, CAP audiograms and latencies did not change significantly, whereas CAP amplitudes and electrode impedances increased, in correlation with each other. In control guinea pigs receiving no ES, the same CAP amplitude and impedance changes were observed over the same long-term period. The EAR and CAP changes can be explained by a variation of the electrical impedance of the electrode/tissue interface. This is possibly due to a change in electrolytes around the electrode under the influence of the ES for the short-term variation, and to an electrode encapsulation by fibrous tissue independent of the ES for the long-term change. In itself, and under the conditions of this experiment, the ES demonstrated no adverse effects on the auditory function and can be safely used for inner-ear exploration.
Acta Oto-laryngologica, 1980
A series of patients presenting with subsequently surgically confirmed central tumour involving t... more A series of patients presenting with subsequently surgically confirmed central tumour involving the auditory pathways were investigated using both transtympanic electrocochleography (TT ECochG) and surface recordings of brainstem evoked responses (BER). While ECochG allows a detailed study of peripheral function, BER allow the investigation of neural conduction up to the level of the inferior colliculus. Valuable information can be obtained from: (1) comparison of the amplitudes of the sensory and neural components of the ECochG; (2) comparison of ECochG, BER and auditory thresholds; (3) time interval measurements between the auditory nerve response (N1 on the ECochG) and the inferior colliculus (wave P4-5 on BER); (4) contralateral comparisons. Similar measurements performed in pure cochlear pathologies, mainly in Meniere's disease, yielded very significant differences.
Archives of oto-rhino-laryngology, Oct 1, 1982
A measure of the (average) rate of discharge versus intensity function of cochlear fibers can be ... more A measure of the (average) rate of discharge versus intensity function of cochlear fibers can be obtained from cochlear-evoked compound action potentials using a tone-on-tone forward masking technique. The rationale for the method is presented. This technique was used to investigate, indirectly, cochlear fiber responses in human subjects, both with normal hearing and with deafness of cochlear origin and showing signs of loudness recruitment. In animals with pathologic cochleas, and change in rate of fiber discharge with intensity is more rapid than in normal animals. The present study confirms that this also is the case in human cochlear pathology and suggests that this abnormal steepening of rate versus intensity functions contributes to the phenomenon of loudness recruitment.
Acta Oto-laryngologica, 1992
Development of the spiral ganglion in white rats was followed during the first 2 weeks after birt... more Development of the spiral ganglion in white rats was followed during the first 2 weeks after birth and morphological characteristics of the two neuronal types (I and II) were examined. In some neurons different stages of partial degeneration leading to formation of residual bodies were found without observation of degenerated cell, supporting the idea that differentiation at this time is not associated with cell death. Contacts between cell body of type II neurons and neuronal endings is reported for the first time. Such axo-somatic contacts previously observed only in monkey and man, also exists in lower mammals.
Archives of oto-rhino-laryngology, Aug 1, 1984
Cochlear action potential thresholds across frequency (AP audiograms) and AP tuning curves were c... more Cochlear action potential thresholds across frequency (AP audiograms) and AP tuning curves were compared in albino (Dunkin-Hartley) guinea pigs and normal pigmented animals. AP audiograms were very similar; on average the albinos had AP thresholds 2-3 dB lower at 2 kHz and below compared with the pigmented guinea pig. AP tuning curves at 16 kHz were, on average, significantly less sharply tuned in the albino, but similar at 8, 4, and 2 kHz. Although we find only small differences in these measures of normal cochlear function, other evidence in the literature suggests that in auditory research the use of "albino" guinea pigs is best avoided.
PubMed, Mar 1, 1978
Sensations induced by electrical stimulation of the cochlea in humans through a promontory or a r... more Sensations induced by electrical stimulation of the cochlea in humans through a promontory or a round window electrode were studied in sixteen subjects. All the patients had total or severe hearing losses. Comparison of the results with the recordings of cochlear potentials gave valuable information in all cases about the site and degree of the disorder. The data on electrically induced auditory sensation are very similar to the general findings of other authors and support the attempts of rehabilitation of the deaf by this means. The most important result reported here is the cancellation of tinnitus during stimulation by positive pulses in most cases, without affecting simultaneous acoustical or electrical hearing. This phenomenon is very reliable and could lead to very important future developments.
Annals of Otology, Rhinology, and Laryngology, Nov 1, 1983
Electrical stimulation of the ear in humans was performed with an extracochlear electrode on the ... more Electrical stimulation of the ear in humans was performed with an extracochlear electrode on the round window. With positive currents, suppression of tinnitus could be induced. With negative currents, auditory sensations were evoked. Since electrical stimulation with DC currents may be hazardous in the long term, it cannot yet be proposed for the suppression of tinnitus. However, electrically evoked hearing sensations with AC currents seem to be of definite interest for some totally deaf patients.
Acta Oto-laryngologica, 1987
An immunohistochemical study was performed on the brainstem of the guinea pig, using a specific a... more An immunohistochemical study was performed on the brainstem of the guinea pig, using a specific antibody against glycine. Glycine-like immunoreactivity was observed in stellate and multipolar neurons in the cochlear nucleus, in the medial and lateral nuclei of the trapezoid body and in the ventromedial periolivary cell group. No immunoreactive neurons were found in the vestibular nuclei. Positive fibre tracts were observed mainly in dorsal acoustic stria and lateral lemniscus. The results are consistent with electrophysiological and anatomical data from the literature concerning the response pattern in the fusiform layer of the dorsal cochlear nucleus and the phenomenon of binaural inhibition in the superior olivary complex.