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Volume 40, Issue Supplement1
Displaying 1-6 of 6 articles from this issue
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Eiji Hakuhisa1997 Volume 40 Issue Supplement1 Pages 3-10
Published: February 15, 1997
Released on J-STAGE: March 18, 2011
JOURNAL FREE ACCESSThis experiment was set up to investigate the effect of chronic electrical stimulation on maturation of the auditory brainstem. Eight kittens were deafened. An intracochlear implant was placed in the left ear and a dummy implant in the right. Each received approximately 1000 hours of chronic electrical stimulation beginning at ages of approximate 100 days, 140 days, 180 days and 500 days after birth. 2-deoxyglucose (2 DG) was used to label regions of active neurons. The soma sizes of the three cochlea, nuclei-anteroventral cochlear nucleus (AVCN), posteroventral cochlear nucleus (PVCN), dorsal cochlear nucleus (DCN), in regions with increased 2 DG uptakewere compared to those without 2 DG uptake.
The average soma sizes of 2 DG-labeled regions were significantly greater than those of 2 DG-unlabeled regions for 100 days and 140 days age groups but no significant differences were observed in 180 days and 500 days age groups. The results indicate that there may be an optimal age for cochlearimplants in deaf neonates.View full abstractDownload PDF (1409K) -
Akio Kato1997 Volume 40 Issue Supplement1 Pages 11-18
Published: February 15, 1997
Released on J-STAGE: March 18, 2011
JOURNAL FREE ACCESSCochlear implants are one treatment for children who are born deaf or become deaf before acquiring language. Using the animal model, we have studied the optimum age for implantation in such cases. Sixteen cats were deafened at 10 days after birth with kanamycin and ethacrynic acid. All were implanted with a 4-electrode array in the left cochlear at age from 100 to over 180 days. The animal are divided into age groups, and within those as controls (stimulation 0 hours) or stimulated : stimulation periods were 1000 hours or more, if possible. In a terminal experiment, each animal received 14C-2-deoxyglucose (2-DG) iv. preceding a 45-minutes stimulation program. The 2-DG label of the right inferior collicullus (IC) with the significant accumulation of label was calculated with using NIH image analyzing system. The 2-DG label increased with ages up to 180 days in either stimulated or unstimulated cats, but at ages of more than 500 days were relatively decreased. It indicates that the development of IC auditory neurons continues up to at least 180 days, perhaps the critical period, whether stimulated or unstimulated, and the development is arrested sometime afterward. The 2-DG label was greater with electrical stimulation than without in the 140 and 180 day groups, more so than in the 100 and 500 day groups. This means that electrical stimulation of the auditory nervous system is very effective even ages of 140-240 days. In conclusion, there appears to be an optimum age for cochlear implantation.View full abstractDownload PDF (2374K) -
Kiyoshi Yonemoto1997 Volume 40 Issue Supplement1 Pages 19-27
Published: February 15, 1997
Released on J-STAGE: March 18, 2011
JOURNAL FREE ACCESSMany articles previously published reported that there is a strong correlation between distortion-product otoacoustic emissions (DPOAEs) and a hearingthreshold level and/or threshold change due to aging. However, the DPOAE response amplitude shows activity of the outer hair cells and the hearing threshold level is affected by not only activities of auditory peripherals but also processing factors in the central system. Therefore, we thought that there should be a different pattern of changes in a hearing threshold and in a DPOAE, due to aging.
In the first experiment, DPOAE response amplitudes were recorded and hearing threshold levels of 409 ears with less than 50 dB HL were measured. The ages of subjects were 20 to 69 years old. Although the hearing threshold level decreased is an almost constant rate with the age, the DPOAE amplitude changing pattern had a knee point around 40 years old in lower frequencies. Then results demonstrated the difference between changes of the DPOAE amplitude and of the hearing level due to aging.
In the second experiment, response times to click sound stimuli were measured in each level of 20, 50 and 80 dB nHL in 30 subjects aged from 20 to 49 years old. The response time was elongated up to 40 ms in all sound intensity levels at the age of 49 years old, and this elongation was started at the age of 30's. In the third experiment, response times to pure tone stimuli were measured in frequency of 800 Hz and 6 kHz in 30 participants aged from 20 to 49 years old. The response time was not elongated significantly with aging, and the difference between in 800 Hz and in 6 kHz was approximately 18 ms in all ages.
From these result, it is suggested that the central auditory function affects more the hearing threshold level in low frequency than the one in high frequency and the deterioration of auditory peripherals will begin in more than 40 years old in low frequency range.View full abstractDownload PDF (1332K) -
Nobuhiro Suzuki1997 Volume 40 Issue Supplement1 Pages 28-39
Published: February 15, 1997
Released on J-STAGE: March 18, 2011
JOURNAL FREE ACCESSThe appearance of event-related potential (ERP) is related to nerve system in cerebral cortex, that can be to an objective proof that a stimulas was understood. We measured the ability of directional hearing by using CNV and P 300, and studied the fundmental character and the possibility to clinical medicine of them. Testing of 20 volunteers in CNV, 15 volunteers in P 300 with normal hearing, we measured the average potential in CNV and the latency and the amplitude of the peak in P 300 of each time difference between ears (ΔT).
Then we compared objective threshold in ΔT by ERP and subjective threshold in ΔT. Measurement in CNV average potential was undergone by Burian method (compare with control) and Prevec method (without control), thus the potential by the former method is lower than the latter and there was no correlation in the potential of each ΔT measured by both method. We refer the importance of control, because we sometime can see the wave form like CNV in control, especially when uncertainly discriminated ΔT. Following odd-ball paradigm, P 300 of directional hearing test has similarity to that of frequency discrimination, and the appearance is more influential by rate of target stimulation than kind of stimulation. In comparison with subjective threshold in ΔT, CNV method is more approximate than P 300 one.
We tested a cerebello-pontine angle tumor case and a psycogenic deafness case by CNV and P 300, it was concluded that directional hearing test by them was usefull as a clinical test, especially psycogenic deafness.View full abstractDownload PDF (2060K) -
Shinobu Nohara1997 Volume 40 Issue Supplement1 Pages 40-51
Published: February 15, 1997
Released on J-STAGE: March 18, 2011
JOURNAL FREE ACCESSWe studied masking level differences by using two equipments for directional hearing test by utilizing electrical circuit and putting self-recording apparatus when the interaural time differences of signal (5) and noise (N) were changed individually, and obtained follwing results.
1. S was 250 Hz pure tone and N was same central frequency band on binaural, MLD became larger as separation of interaural time differences between S and N became farther. But on monaural there was not this tendency.
2. As frequency of puretone signal became higher more than 125 Hz, MLD was decreasing gradually, and MLD almost disappeared more than 2000Hz. 3. On the same condition, MLD of the retrocochlea deafness group between S0N0 and S (+650) N (-650) was extremely smaller than one of normal hearing group, and that of cochlea nerve deafness group was neutral.
4. When S was lowpass filtered click, MLD of binaural was found against that of monaural.
5. When S was the speech discrimination of 57 and 67 type and N was weighted noise, MLD of retrocochlea deafness was smaller than normal, and that of cochlea deafness was larger.
6. The relation between MLD and directional hearing ability was dependence.
7. Phenomenon of MLD was considered accordig to the theory of Bergeijk's directional hearing ability.
8. MLD of pure tone on fixed condition was useful for diagnosis of retrocochlea deafness.
9. Binaural effect and usefulness of hearing aids of both ears were discussed.View full abstractDownload PDF (1746K) -
ADVANTAGE OF COMPUTER-AIDED THREE-DIMENSIONAL RECOSTSRUCTION METHOD TO MEASUSEMENTS OF SCALA TYMPANIRikako Karigane1997 Volume 40 Issue Supplement1 Pages 52-58
Published: February 15, 1997
Released on J-STAGE: March 18, 2011
JOURNAL FREE ACCESSThis paper describes the application and advantageof computer-aided three-dimensional (3-D) reconstruction to measurements of the distance, diameter, crosssectional area, volume of scala tympani. Furthermore, the diameter of cochleas were compared with those from MRI films and the density of spiral ganglion cells of the cochlea inserted cochlear implant (CI) were measured for the evaluation of the 3-D reconstruction methods. The length of the Organ of Corti was 35.58 mm (mean), longer than those by 2-dimensional reconstruction methods. The diameters of outer and inner walls of basal turn of cochleas are6.77 mm and 3.01 mm respectively. The volume of scala tympani is 37.16 mm3, and the cross-sectional area increased rapidly within the first 3 mm from the basal end, then decreased slowly. There were somewhat new bone growth and fibrous changes in the scala tympani around the electrode array and the decreased density of spiral ganglion cells on the CI's case. Thus, 3-D reconstruction method is expected asa new method in place of conventional 2-D reconstruction methods.View full abstractDownload PDF (6052K)
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