Liquid ionization mass spectrometry was applied to analysis of middle ear effusions. Materials were obteined from 10 ears of Children, 7 ears of adults and three serums. Mass spectra between m/z 10 and 400 were directly measured during heating the material. Averaged mass spectra and desorption profiles are printed out by a microcomputer system. Eight characteristic peaks at m/z 61, 84, 86, 90, 114, 235, 257, 369 were detected for samples from patients and also from serums. Results indicate that substances of molecular weights under 400 in middle ear effusions may come from a part of the blood.

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Arachidonate metabolism in the middle ear effusion was studied to clarify substance (s) mediating inflammatory responses in secretory otitis media. The concentrations of prostaglandin (PG) E2, F2α and 6 keto-PGFlα were higher in the middle ear effusions of children than in those of adults. However, the significant differences between the levels of PGs in the serous, mucoid and glue effusions of children were not observed and it was found that there was no correlation of the PG levels with cell infiltration or with plasma leakage into the middle ear space. These results suggest that PGs in the middle ear effusion do not have important roles in the disease process. In this report, it was also demonstrated that the middle ear effusion had a strong activity converting leukotriene C4 to E4.

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Platelet-activating factor, a biologically active ether lipid, has been suggested as an important mediator in inflammation. In order to characterize the biochemical features of OME, we have examined the PAF activity using 17 middle ear fluids. In 7 ears, we detected the PAF activity, which was characterized by the behavior on thin layer chromatography and by the treatment of CV-3988, a specific antagonist to PAF molecule.
From the above, there are cases that PAF presents in middle ear fluids from OME, and it may suggest that PAF play an important role in the pathogenesis of OME.

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Lipid A is a covalently bound lipid component of the gram-negative bacterial lipopolysaccharide, and represents the biologically active component in endotoxins. For the detection and quantification of lipid A in middle ear effusion (MEE) from patients with otitis media with effusion (OME), we raised antisera against lipid A in mice by repeated immunization with the conjugates with lipid A of Salmonella minnesota Re595 and bovine serum albumin, and developed an competitive enzyme-linked immunosorbent assay (ELISA) specific for lipid A. In the ELISA, 10 out of 15 samples from serous type of MEE (13.57±2.17 μg/ml, mean±SE), and 5 out of 6 from mucoid type of MEE (17.73±4.34 μg/ml, mean±SE) were positive. Lipid A present in MEE may contribute to the pathogenesis of both types of human OME.

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The etiology of otitis media with effusion (OME) has not been conclusively established. The biochemical characteristics of middle ear effusion (MEE) indicate inflammatory state. Although prostaglandins (PGs) have been detected in MEE, the exact measurement of PGs has not been made. In this study, concentrations of PGs were measured by radioimmunoassay (RIA) in human MEE. Each sample of MEE from OME was devided into two groups, which were serous effusions and mucoid ones. The main PG in both serous and mucoid effusions was TXB₂, followed by PGE₂. PGD₂, PGF_2α, and 6ketoPGF_1α were also found in MEE with a smaller quantity. The amounts of each PGs in mucoid effusions were two or three times higher than those in serous effusions. But protein concentration is almost the same between mucoid and serous group. These results suggest that PGs may play important roles as a mediator of the inflammatory response in the pathogenesis of MEE.

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To investigate the influence of middle ear effusion (MEE) on perilymph (PL), an experimental otitis media with effusion (OME) was manufactured in chinchillas by injecting the tympanic cavity with immune complexes. The mean concentrations of albumin, IgG, histamine and prostaglandin E₂ (PGE₂) were significantly greater in PLs from OME induced ears than in those from normal control ears. ³H-PGE₂ placed on the round window membrane of pathologically affected ears passed into PL in significantly greater amounts than those in normal control. The finidings of the present study indicate that MEE affects biochmical milieu of PL.

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Bacterial antigens of Str. pneumoniae and Str. mitis in middle ear effusions (MEEs) were measured by ELISA using specific antisera. Antigen levels were compared with cytological findings and global appearances of MEEs. The antigen levels of Str. mitis were found to be related with the cytological finding of MEEs. Antigen levels in few cell type- and in neutrophil dominant type-MEE were lower than those in other types. The antigen levels of Str. pneumoniae in purulent type- and mucopurulent type-MEE were highter than those in mucinous type- and bloody type-MEE. The results suggest that the relation of various bacterial antigens in the MEEs, possibly derived from the nasopharynx, may stimulate the middle ear mucosa and may be one of causes for the chronicity of otitis media with effusion.

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In OME in children, the amounts of total and specific IgG antibodies against H. influenzae (nontypable) were investigated middle ear effusions (MEEs) in comparison with sera by laser nephelometry and ELISA. The amounts of IgG in MEEs were higher than those in sera. The MEEs/sera ratios of specific IgG antibodies in serous- and mucoid-groups were higher than that in glue-group. These data show that the bacterial infection and subsequent immune response contribute the prolongation of OME in serous-, mucoid-groups, while other factors add to them in glue-group.

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Tympanic wall of the rat cochlear duct was fixed by intracardial perfusion with 4% paraformaldehyde and embedded in LR-Gold. The urtrathin sections were incubated with antibody against α-subunit of (Na, K) ATPase purified from rat kidney, subsequently with protein A gold complex. In the organ of Corti, a few particles were found on the plasma membrane of the inner and outer hair cells. The border cells and the inner phalangeal cells surrounding the inner hair cells were moderately, labeled with gold particles on their basolateral membranes. Gold particles were also found on the basolateral membrane of the T-shaped cells in the spiral limbus.

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Glycosphingolipids were extracted from 200 pieces of rat cochleas, and separated into neutral glycosphingolipids and acidic glycosphingolipids using DEAE-Sephadex A-25 ion exchange chromatography and analyzed with high performance thin layer chromatography (HPTLC). Ceramide monohexoside is a chief component of the neutral glycosphingolipids, while sulfatide and GM3 are chief components of the acidic glycosphingolipids, and furthermore several kinds of gangliosides are detected with two dimensional HPTLC in rat cochlea. This pattern of the cochlear acidic glycosphingolipids is similar to that of the renal acidic glycosphingolipids.

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An analysis of amino acid content was performed as the sample volume withdrawn through the round window (RW) was varied from 100nL to 5μL. Many kinds of amino acids, including glutamine, glycine and alanine, were measured by HPLC (Physiological Pico-Tag, Waters). Our data suggest that perilymph samples taken through the RW are contaminated with cerebrospinal fluid (CSF) if more than 200nL is withdrawn. If scala tympani perilymph is sampled from the third turn, larger volumes (up to 1.7μL) can be withdrawn without significant CSF contamination.

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The amino acid contents of perilymph in the scala tympani was measured by using High Performance Liquid chromatography. The perilymph was collected into the micro-glass pipette via the round window. The samples were derivertized to the PITC-amino acid, and were analyzed to clarify the kinds and the concentrations. The normal perilymph had a unique contents such as lower Asp and Glu, higher Gly, Ala and Lys. In test groups, several amino acid were increased those values, Asp, Glu, His etc, with enforced Anoxic Anoxia, ligation of A. basilaris and some drugs which were taken damages in the inner ear.

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Many kinds of studies of inner ear vessels have made before. We studied the relation between vascular variation around the internal acoustic meatus and the facial, vestibular and cochlear nerve with casting method using Mercox resin and microfil rubber. Arterial loops of all guinea pigs were observed similarly to human cerebellar loops, which didn't originated from the anterior inferior cerebellar artery but from the common cochlear artery. No loop observed within the internal acoustic meatus on all guinea pigs different from human cerebellar loops. The subarcuate artery of the guinea pig originated from the internal auditory artery, and vasculized paraflocculus of the cerebellum.

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In the present study, imprints on the corrosion casts of blood vessel were observed under a scanning electron microscope. The results obtained were as follows
(1) In the artery and arteriole, their imprints were long, regular spindle-shaped, and their long axes ran almost in parallel to the blood flow.
(2) In the vein, surface of the corrosion cast was smooth and oval-shaped nuclear subsidences were observed.
(3) In the capillary, surface of the corrosion cast was smooth and nuclear imprints were not observed.
(4) In the cochlear plexus capillary, fenestrations of the endothelial cells were observed.

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It has been reported that there are two types of barriers, size barrier and charge barrier in the glomerular basement membrane of the kidney and they play an important role in the vascular permeability. In the present, we observed electronmicroscopically the anionic sites of the charge barrier in the guinea pig stria and spiral ligament. By the modification of Schurer's method, cationic polyethylenimine (PEI, MW 1800) as a tracer was injected intravenously or immersed through the round window. The results showed a PEI localization forming two strata with regular interspaces in the capillary basement membrane of the stria and spiral ligament. This finding was similar to that seen in the glomerular basement membrane of the kidney.

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Ten minutes after the removal of the right superior cevical ganglion (SCG), horseradish peroxidase was intravenously injected and then the both cochleas were fixed by perilymphatic infusion with glutaraldehyde. Eight minutes after the cochlear fixation animals were killed by decapitation. The capillaries of the stria vascularis in the right side were wider than in the left side in three of five cats, but the diameter of the capillaries of the spiral ligament was statistically no different between right side and left side excent only one cat. When the cochleas were fixed after decapitation the blood sludging was observed in 96% of the strial capillaries in left side, and it was observed in 50% of them in the right side (SCG removal side).

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We studied the histopathological changes in the endolymphatic sac. Thirty one Hartley guinea pigs were immunized with stria vascularis of rabbits in Freund's complete adjuvant, and 13 guinea pigs were inoculated with analphylatoxin via the carotid artery. Twelve guinea pigs with a normal Preyer's reflex, served as the control group. The temporal bones were fixed in 10% buffered formalin, embedded in celloidin, cut into section of 13μ and stained with hematoxylin and eosin.
We observed and counted macrophages in the whole endolymphatic sac. We could not find any histopathological changes, but there were more macrophages in the endolymphatic sac, in the immunized and inoculated animals than in the control ones. The results suggests that the endolymphatic sac is involved in the immune response.

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The morphology of endolymphatic sac in golden hamster was observed by light and electron microscopy and the distribution of cytokeratin (predominantly 56kd and 64kd) was studied immunohistochemically in the epithelium of the endolymphatic sac. Cytokeratin immunoreacivity is commonly localized in the cytoplasm of the epithelial cells. But some epithelial cells indicate weaker reactivity or none. The subepithelial tissue and intraluminal space show no immunoreaction for cytokeratin. By the ultrastructural study, the epithelial cells of the endolymphatic sac have many bundles of 10nm-filaments. So the result of this study suppose the epithelial cells of the endolymphatic sac have many cytokeratin bundles in the cytoplasm.

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The light microscopical and ultracytochemical localization of Na⁺-K⁺ ATPase (ouabain-sensitive, potassium-dependent p-nitrophenylphosphatase) in the guinea pig endolymphatic sac was studied by a newly developed lead citrate one step method. The cytochemical reaction product was detected in the epithelial cell layer of the endolymphatic sac at the light microscopical level. At the electron microscopical level, the reaction product was located in the basolateral plasma membrane of both the dark and the light cells. The results suggest that Na⁺-K⁺ATPase may play a role in the ion transport mechanism in the endolymphatic sac.

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20 guinea pigs were immunized with horseradish peroxidase (HRP) and challenged with 5mg of the same antigen in the tympanic bulla. The appearance of plasma cells in the inner ear structure was examined immunohistochemically by ABC method. 5 animals out of a total of 20 showed sufficiently increased plasma cells in the subepithelial connective tissue of endolymphatic sac (ES). Those plasma cells showed positive reactions mainly with IgG followed by IgM, and with IgA, slightly. Some of these plasma cells were considered to contain the specific antibody against HRP. The results indicate the role of the ES as a local immune response region as well the existence of an immunological intercourse from the middle ear to the ES.

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Stresses are generally considered to be one of the causes of Ménière's disease. So we first tried to make active endolymphatic hydrops in guinea pigs by four kinds of stress-stimulations. Although active endolymphatic hydrops were made, its occurrence rate was low. With intravenous injection of the enzyme, horseradish peroxidase (HRP), it was revealed that the stria vascularis vessels in experimental guinea pigs were more permeable than those in sham operative ones.

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The fine structure of the utricle was observed by transmission electron microscopy two months after obliteration of the endolymphatic sac and duct in three rabbits. All animals were found to have distended Reissner's membrane. In the utricle vacuolization with disruption of mitochondria in hair cells and supporting cells was observed. Cilia and nerve chalice appeared normal.
One animal showed slight deviation of the head towards the operated ear, while the other exibited no obvious disorder of the vestibular function.

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The production of endolymphatic hydrops is tried by cII or monoclonal anti-cII antibody local challenge to the endolymphatic sac as well as combination of cII local & systemic immunization. 5 of 11 (45%) guinea pigs which received anti-cII antibody showed abnormal vestibular function. 3 of 17 (17%) guinea pigs which received cII local & systemic immunization showed vestibular hydrops, while control group showed normal. The both abnormal vestibular function group and formation of vestibular hydrops group are regarded due to the antigenantibody reaction with cII in the endolymphatic sac or duct.

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The effect of perilymphatic pressure upon the CM threshold was examined the 30 guinea pigs with endolymphatic hydrops. When the pressure of 300mmH₂O was applied to the scala tympani of the basal turn, the 500Hz CM threshold shift in hydropic ears were significantly smaller in the early stage in contrast to the normal ears and progressively returned to the normal value as the time elapsed after the surgery. The findings in the present study may be the time course of the scals media pressure of the hydropic ears, i. e. the initial increase and following decline toward the normal value.

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Endolymphatic hydrops was induced in 7 albino guinea pigs by obstructing the endolymphatic sac on one side. The effects of glycerol infusion (3g/kg bw) on the cochlear potentials were investigated at the 6th postoperative month. Glycerol did not improve the thresholds and amplitudes of the cochlear microphonics and compound action potentials. Furthermore, in several animals slight elevation of the AP thresholds for the click and the tone bursts of the middle and high frequencies was seen after the glycerol infusion. The SP amplitudes for the click were decreased in 1 hour in 4 animals and recovered in 2 hours after the infusion in 2 animals out of the four. This phenomenon may suggest the shift of the basilar membrane induced by the glycerol administration.

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The endolymph-perilymph shunt operation was performed on the 20 guinea pigs with endolymphatic hydrops which had been induced by silver nitrate method. The shunt was created between the scala media and the scala tympani through the basilar membrane in the basal turn. After various survival time (3 hours-27 days), the animals were sacrificed for the pathological study. Ten animals out of 20 showed the shunt, while the other 10 did not, probably due to the healing of the shunt. In the short post-operative term group (3 hours-3 days), the animals having shunts showed slight membranous collapse. In the long term group (7 days-27 days), however, the animals showed hydrops in spite of the existence of the shunt. Severe degenerative change of the Corti's organ and severe atrophy of the stria vascularis were observed adjacent to the shunt area.

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The route of entry of virus into the inner ear is still controversial. In this study seronegative guinea pigs were given intracardiac inoculations with varying doses of guinea pig cytomegalovirus. After 8 days, one animal that received 200 μl of virus showed labeling in the modiolar blood vessels and perivascular infiltrates. Two of 4 animals that received 300 μl of virus showed aditional labeling in the spiral ganglion cells. At 8 days, animals inoculated with >100 μl of virus showed lebeled cells in multiple organs. These data suggest that one possible route of guinea pig cytomegalovirus into the inner ear involves viremic spread to modiolar blood vessels and subsequent spread to spiral ganglion cells.

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HVJ (Sendai Virus) was inoculated to 20 guinea pigs. The serum anti-viral antibody titer was studied by hemagglutinin inhibition test after intralabyrinthine inoculation and was compared with that after intraperitoneal inoculation. The labyrinthine and peritoneal routes of HVJ presentation read to a parallel change in antibody titer. The group with low antibody titer (≤×8) before the HVJ inoculation resulted in a significant rise in antibody titer over a 2 or 3-week period. The group with high antibody titer (≥×16) failed to result in a significant rise.
This study indicates that the inner ear is an effective route of antigen processing which results in the acquisition of immunity.

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Hantaviruses, which cause hemorrhagic fever with renal syndrome (HFRS) in humans, were inoculated intraperitoneally into newborn rats. Inner ears and other organs were examined by immunohistochemical and histopathological methods. Viral antigens were detected in Reissner membrane, stria vasculasis and spiral ganglia of the inner ear, spleen and kidney. Virus was isolated from blood of the rats which were sacrificed at one year after infection. These results suggest that Hantavirus may play same roles in persistent infection and the damage of auditory system.

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Relationship of circulating immune complexes to some of inner ear disorders has been suggested recently. Thus, bovine serum albumin (BSA) nephritis, a model of chronic serum sickness, was made and morphological studies of the cochlea were performed using light microscopy, scanning electron microscopy, transmission electron microscopy and immunofluorescent antibody method. In the present study, no morphological changes were observed in the cochlea.

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As the mechanism of pathogenesis of relapsing polychondritis, autoimmunity to type II collagen has been suggested. Audiovestibular disorders is known to be often associated. Crossreactivity between anti-human type II collagen antibody and type II collagen of guinea pigs or rats was examined by immunofluorescence. Type II collagen which crosses to human antibody was detected in osseous spiral lamina and spiral ligament. The evidence of presence of type II collagen in human inner ear suggest that the antibody binds to inner ear and results in audiovestibular disorders.

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In the primary KLH inner ear challenge, free KLH deposits were seen in the perilymphatic spaces of the cochlea and the vestibule and in the lumen of the endolymphatic sac and the perisac connective tissue. In the secondary KLH inner ear challenge, free KLH deposits and KLH phagocytic cells were seen in the same regions of the primary KLH inner ear challenge. Allmost all free KLH deposits were removed from the cochlea, the vestibule and the endolymphatic sac within 3 days, however KLH phagocytic cells seen in the cochlea and the endolymphatic sac stayed at least 5 days. These findings suggested that KLH antigens injected into the scala tympani were transffered from the perilymphatic space into the endolymphatic space in the status of immune reaction.

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The perfusion of the scala tympani with air at a rate of 200 or 400 μl/min initially caused a slight decrease of EP (10-15 mV due probably to the pressure effect), but the EP (although recording was notchy) remained at this level throughout the perfusion of 20-30 minutes and returned quickly to the original level when the perfusion was stopped. In contrast, the CM and AP showed a marked (but reversible) decrease during the air perfusion.
This study showed that the replacement of the scala tympani with air causes hearing impairment probably due to a reversible interference with the CM and AP production mechanism rather than the strial dysfunction.

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The Cl^--concentration in endolymph (Cl^--endo) and the EP were recorded simultaneously from the basal turn of the cochlea of guinea-pigs with a double-barreled Cl^--electrode during anoxia and after furosemide or glycerol injection. From the experimental results, the following conception could possibily be suggested: (1) The permeability of Cl^- between endolymph and perilymph is less than that of K⁺ and Na⁺. (2) There is no necessity for assuming the existense of Cl^--pump which draws out Cl^- to the stria from endolymph and participates in generation for EP. (3) The stability of Cl^--endo in various conditions must be due to the solvent traction. (4) At the condition of too much rapid dehydration in endolymph which induced by such as glycerol injection, the movement of Cl^- does not always follow to the rapid water movement resulting in the slight increase of Cl^--endo.

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We examined the effects of cholinergic drugs on the cochlea by electrocochleography.
AP amplitude was decreased by cholinergic drugs and this effect was surpressed by anticholinergic drugs. The amplitude of CM was not changed by cholinergic drugs. These results suggest that the cholinergic system plays a role in the regulation of sound stimulus.

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The endocochlear potential (EP) was recorded during the perilymphatic perfusion with sodium fluoride, cholera toxin and forskolin known as adenylate cyclase stimulants. Sodium fluoride and cholera toxin did not change the EP, whereas forskolin produced a reversible EP increase in a dose-dependent manner. Ischemia produced a large negative EP when the EP was increased by the administration of forskolin. It suggests that the EP increase produced by forskolin does not result from the decrease in the negative component of the EP but from the increase in the positive component of the EP.

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Recently, the attention has been paid to Ca ions in maintaining EP, inv the way that Ca concentration difference between perilymphatic and endolymphatic solution contributes to EP as the diffusion potential of Ca ions. We have investigated the changes in EP when free Ca ions in perilymph was removed by high concentration EGTA. With the perilymphtic perfusion of 10 mM EGTA, the EP fell from about +80 mV to 67 mV. The change in EP was transient, and recovered to the original level in another several minutes in spite of successive perfusion on EGTA. With the perilymphatic perfusion of 4 mM EDTA the EP did not change significantly. Probably, Ca ions are mobilized from the surrounding tissues into perilymph. So, high concentration of chelating agent is required to obtain the conditions of free Ca.

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The perilymphatic space of normal or Kanamycin (KM) -poisoned guinea pig was perfused with K-free artificial perilymph. Perfusion of scala tympany (ST) or scala vestibuli (SV) of normal guinea-pig cochlea led to a gradual decline of the EP to about 0 mV. Perfusion of SV of KM-poisoned guinea-pig cochlea also declined the EP to about 0 mV, but perfusion of ST decreased the EP to only about 40 mV. It is assumed that negative potential could be produced by K-free perfusion of ST, which is suppressed in KM-poisoned guinea-pig cochlea.

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Positive potentials were recorded in the cells of stria vascularis in Kanamycin-deafened guinea pigs. Gradual positive steps were observed in normal and Kanamycin guinea pigs during penetration of the cells of stria vascularis. Anoxia depressed these positivd potentials in both animals to almost the same extent, namely, approximately 20 mV at the 5th minute and 0 mV at the 30th minute. These results suggest the strial cells have almost the same electrophysiological function in normal and Kanamycin-deafened guinea pigs.

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Endocochlear potential (EP) and Cl^- activity in the scala media were recorded by means of Cl^- sensitive double-barrelled microelectrodes in the second turn of the cochlea of the guinea pig during perilymphatic perfusion with furosemide and ouabain. Furosemide produced a slight increase in Cl^- activity during the EP reduction to the level near 0 mV, whereas ouabain decreased Cl^- activity accompanying the EP reduction to the level near 0 mV. The effect of furosemide on Cl^- activity in the scala media may be explained by the inhibition of active Cl^- extrution pump in the stria vascularis.

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The K⁺ activities were recorded from the basal turn of each scala of the cochlea with the double barrelled K⁺ sensitive electrode before and after the start of the perfusion with artificial perilymph containing 20 mM KCl and 130 mM NaCl. When theperfusion was stopped, the K⁺ activities decreased rapidly in both scala vestibuli and tympani. Decrease of K⁺ activities in the scala tympani was slower in the animal with cochlear aqueduct blocked. These results suggest that longitudinal flow through the cochlear aqueduct is predominant in the scala tympani, but radial flow in the scala vestibuli.

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The first irritative and then the second paralytic nystagmus are observed after introducing saturated KCl solution to the tympanic cavity of guinea pigs. This is thought to be induced by the change of K⁺ consentration delivered through the round window to the labyrinth. By measuring the time course of the K⁺ activity change in perilymph using the K⁺ specific microelectrode method, the following result was obtained: K⁺ activity of perilymph increased so rapidly to higher degree in 20 minutes after introducing KCl solution and then decreased gradually to the half of the peak in 120 minutes. That was thought to be recovered to the normal level after 48 hours.

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H₂ clearance of the inner ear between endolymphatic and perilymphatic system was measured simultaneously using bi-channel hydrogen clearance monitor. Two special hydrogen-sensitive microelectrodes were applied to the small hole that was made at stria vascularis and round window. The half life times (T_1/2) of both endolymphatic and perilymphatic H₂ clearances were examined in order to study these metabolic differences. Also influences of furosemide and glycerol were examined. The personal computer (NEC PC-9801) and unique soft ware made by ourselves were used to analyze these data.

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Dynamic changes in six parameters namely, cochlear blood flow and muscular blood flow by laser Doppler flowmeter, perilymphatic and systemic arterial oxygen tension by polarography, systemic arterial carbon dioxide tension and pH by field effect transducer, against changes in mean systemic blood pressure were analysed. A negative correlation was noted between the systemic oxygen tension and cochlear oxygenation. Cochlear blood flow and oxygenation showed partial dissociation at the mean systemic blood pressure range of less than 80 mmHg.

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Six rabbits were exposed to the sinusoidal linear oscillatory stimulation (vertical, longitudinal, transverse) and their physical and biochemical response were recorded. Main results were as follows; 1. Heart rates decreased during exposure to the longitudinal linear oscillatory stimulation. 2. Increase of respiratory rate after the vertical stimulation prolonged. 3. Increased rate of plasma adrenaline after the longitudinal stimulation, plasma noradrenaline, blood sugar and fatty acids after the vertical stimulation were larger. We think these results suggested that whole body response by linear oscillatory stimulation participated in not only otolith organ but also movement of internal organ and blood body axis direction.

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We examined on vestibulo-ocular reflex (VOR) with systemic administration of TRH and DN-1417 (TRH derivative) in squirrel monkeys. Our results showed that DN-1417 (0.02-2.0mg/kg) had a decremental effect on the gain of VOR for 60min after injection. However, a higher dose of TRH (2mg/kg) showed a inhibitory effect on VOR gain 15-30min and a facilitatory effect 60min after injection. It might be pointed out that TRH and DN-1417 had effects on VOR related neurons in CNS.

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The influence of the middle ear pressure on the otolith system was investigated in anesthetized cats. Extraaxonal recordings of action potentials were performed in the vestibular nerve fibers and in the neurons in the lateral vestibular nucleus that responded to lateral or anteroposterior steady-state tilt. Positive or negative pressure was applied to the ipsilateral middle ear during the recordings. Seventy three percent of the fibers and sixty three percent of the neurons responded to changes in the middle ear pressure. These response rates were higher than those that were previously reported on the units innervating semicircular canals. It was suggested that hair cells in otolith organs are more sensitive to changes in the middle ear pressure than those in semicircular canals.

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The behavior of the primary horizontal canal neurons to the continuous pendular oscillation was studied in seven albino guinea pigs. Sixteen neurons whose spontaneous firing pattern were regular 5, intermediate 8 and irregular 3, were subjects of the present experiment. The maximum and the minimum numbers of oscillation at 0.3Hz were 250 and 40, respectively. No remarkable changes of the gains to angular velocity and the phase lag to the angular acceleration were observed.

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We tested the hypothesis that Chinese listners have abnormal difficulty discriminating spectral patterns. Both Chinese and Japanese listeners were asked to discriminate a stimulus with time-compressed version of the Japanese mono-syllables lists. We had developed digital processing techniques for speech by Used of Pointer Interval Control Overlap and Add. Listeners were administered a 30% time-compressed version of the syllables lists. Results in Chinese and Japanese revealed that in unvoised and voised plosives of consonant part of Japanese syllables were found to significantly affect confusion, especially /gi/ and /bi/, were confused at /ri/, also, /pa/ and /pya/ were confused at /a/ and /kya/. These findings suggest that a time-compressed speech that may be moderately useful in the identification of time-resolution.

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In view of the excellent communication system of birds, their hearing mechanism was examined in relation to ABR. Seventeen male parakeets were exposed to white noise (100 and 110dB SPL/1, 2, 3 and 5 hours) and changes in ABR before and after exposure were compared with those of guinea pigs previously reported. The threshold of ABR rose immediately after exposure in birds as in guinea pigs but the prolongation of latency of the first wave was less remarkable in birds than in guinea pigs. The threshold value before exposure was obtained in 24 hours. White noise exposure caused NITTS to birds ear but didn't cause NIPTS.

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