The vestibuloocular reflex () stabilizes retinal image during head motion by counter rotating the eyes with nearly an equal speed. When the is inadequate the image slip on the retina evokes a visually-driven response to reduce the slip. If this situation persists, the recalibrates its characteristics so that it can produce adequate eye movements without the aid of the visual system. This phenomenon is called motor learning. In the laboratory it is induced chronically by magnifying or minifying lenses installed on the animal for several days to months, or acutely by exposing it to the visual stimulus moving in- or out-of-phase with a vestibular stimulus for several hours. It has been known the cerebellar flocculus complex (FL) is necessary for this motor learning, but its functional role has been in debate due to the inconsistent results of flocculectomy on the learned animals. We have addressed this problem by performing single unit recording from FL Purkinje (P) cells before and after acute and chronic vertical motor learning in squirrel monkeys. We showed that the information content encoded in P cell firing changes in parallel with the learning in different ways for acute and chronic cases. We also showed that acutely learned gains decay significantly while chronically learned gains do not. These results with other lines of evidence suggest that the memory of the acute motor learning is expressed mainly in FL while that of chronic involves other site as well. [Jpn J Physiol 54 Suppl:S34 (2004)]

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Ionotropic glutamate receptor δ2 subunit (GluRδ2) is specifically expressed in cerebellar Purkinje neurons (PNs). GluRδ2 knockout mice (δ2-/-) show the impairment in synaptic regulation and motor coordination. To elucidate how the GluRδ2 deficiency affects motor coordination, we have analyzed their eye movements and found that δ2-/- showed abnormal spontaneous and reflexive eye movements. In δ2-/-, eyes moved continuously with 1Hz and 10 Hz oscillatory components even if no stimulus was applied. δ2-/- showed a large phase delay in the optokinetic response and a high gain in the vestibulo-ocular reflex. Simultaneous recordings of the spontaneous eye movement and the activity of a floccullar PN revealed that PNs in δ2-/- tended to generate several forms of spike activities presumably induced by climbing fiber inputs. These activities showed the 10 Hz periodicity and correlated to the spontaneous eye movement. Abnormalities in spontaneous and reflexive eye movements were reduced by destruction of inferior olive nuclei by administration of 3-acetylpyridine. These results suggest that altered climbing fiber activities are related to abnormalities in the spontaneous and reflexive eye movements in GluRδ2 knockout mice. [Jpn J Physiol 54 Suppl:S179 (2004)]

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The site selection of a very-high-frequency omnidirectional radio range (

) is a difficult task since many objects, buildings, towers, wires, sea, and mountains may give adverse effect on the omnirange radiation pattern.

This report deals with the effect of the nearby objects on the operation of the

.

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【はじめに】
転倒は様々な要因で起こる。その中でも前庭機能障害，空間識失調，眩暈に対するリハビリテーションはあまり知られていない。今回，ロマリンダ大学で前庭のリハビリテーションを学ぶ機会を得ることができ，その評価・治療を前庭のシステム，機能障害を加えて報告する。
【Vestibular system】
Vestibular systemは主に内耳にある5つの末梢器官，脳幹と小脳にある前庭核，Vestibulo-ocular-reflex（以下）Vestibulospinal reflex（以下VSR）の運動出力系の3要素から構成されている。末梢器官は三半規管，卵形嚢，球形嚢である。各器官には細毛が存在し，その細毛が頭部の傾きを感じ取り，第8脳神経を通して脳に伝えられる。は頭部の動きに対して注視の安定に働く反応であり，VSRは伸筋活動を促進したり，抑制したりすることにより全身の平衡を保つ反応である。
【Disorders of the Vestibular system】
末梢のvestibular systemの障害は末梢器官や第8脳神経の神経線維への直接の損傷やbenigo paroxysmal-
positional vertigo（以下BPPV），つまり，卵形嚢の平衡砂が三半規管のcupulaに移動することやあるいは外リンパ液に漂うことによる異常な平衡入力，メニエール病の内リンパ水症によるこちらも異常な平衡入力が挙げられる。一方，中枢障害は脳幹・小脳の梗塞や出血，延髄の血管障害による前庭核の損傷である。他に，脳幹や小脳に起こる腫瘍や脱髄疾患からも前庭核の損傷を引き起こす。
【Assessment】
Vestibular 機能や評価は(Ocular Alignment・Spontaneous Nystagumus・Hallpike-Dix Testなど)12項目あり，VSRの評価は重心動揺計やBalance Clinical testingの7項目の評価(片脚立位、Romberg test・Functional Reach test・Timed Up and Go test・Berg Balance Scaleなど)
【Intervention】
Vestibular Rehabilitationの目的は空間失調や眩暈を減らすことや姿勢コントロールの改良である。主な治療はadaptation，substitution，canal reposi-tioning techniques（CRT），habituationである。評価によって患者の前庭障害が末梢であるのか、それとも中枢であるのかを判断し、上記の治療を使い分けることが大切である。
【終わりに】
まだ日本で確立されていないVestibular　rehabilitationに対して，今後，評価・治療を用いて症例数を増やし，臨床に役立てたい。上記の評価・治療の詳しい解説は本学会で説明する。

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Doppler VHF omnidirectional radio range (D-

) has been widely used as a short-range air navigational system, and there are more than 80 D- stations in JAPAN.

The bearing information of the D-

is generated by rotating sideband antenna on about 6.5 m radius circle. When receiving a D- signal close to the station, the detected signal distrortion in the receiver largely rises with the distance approaches, owing to whirling of the antenna. On this account, there are some cases where sufficient monitor performance cannot be obtained at near field.

In the present paper, we describe the causes of subcarrier amplitude fluctuation and calculate the detected signal distortion at near field.

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(VHF omnidirectional radio range) is a short-range air navigation assistance facility of international standard providing directional information. The bearing of is measured by the phase difference of two 30-Hz sine waves, reference and variable phase signals. Recently, the bearing accuracy of receiver has been made great improvement using a digital signal processing technique in place of an analog processing one. However, the bearing stability of a digital signal processor with zero cross detection method is not good when the receiving signal level is low or the distortion of detected signal is large. In order to eliminate these defects, it is worked out a new signal processor using a digital phase lock technique. It is replaced the reference and variable signals with two square waves which synchronize to these signals. The experiment results of the new signal processor are as follows. The bearing accuracy is less than 0.1°and the bearing fluctuation is less than 0.2°at the level of the minimum receiving sensitivity (-90 dBm).

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Doppler

has the advantage of improvement with respect to the site effects compared to conventional .

Single-sideband Doppler

has been widely operated because of its simplicity and low cost compared to double-sideband Doppler , while it has bearing error caused by counterpoise eccentricity effect and site effects.

This paper describes mathmatical analysis and test results on bearing error for SSB and DSB Doppler

.

The analysis and test results indicate that duantal bearing error and site effects caused by undesired amplitude modulation are reduced remarkably compared to SSB Doppler

.

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A rotatory test is less bothersome to subjects than bithermal caloric test. A rotatory stimulus of the semicircular canals is unrelated to the anatomical structure of external auditory meatus or temporal bone, making it possible to measure more exactly the relationship between stimulus and response.
We developed a new otolith function test by centric and eccentric pendular rotation. Using this method, we investigated the otolith function of 26 patients with peripheral vestibular disorders (7 with unilateral peripheral vestibular disorders,11 with Meniere's disease and 8 with vestibular Meniere's deseases) obtaining the follwing results. First, all patients with peripheral vestibular disorders who were investigated at least 1 month after the onset of the disease showed normal function. Second patients with Meniere's disease and vestibular Meniere's deseas had otolith dysfuntion within 1 month after the first or the most recent attack. There fore, we postulated the existence of a mechanism which compensated for the loss of the otolith-ocular reflex system in patients with unilateral poeripheral vestibular disorders.

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It is well known that administration of some substances whose specific gravity and density are different from those of body fluid causes positional nystagmus.
In this study, we investigated the effects of administration of D₂₀ as a negative geotropic nystagmus inducer and alcohol as a positive nystagmus inducer on the quantitative assay of positional nystagmus as well as on the gain and phase of vestiburoocular reflex of the rabbits. In addition, based on the results obtained in this experiment, we have made some studies about the mechanism of phase lag of observed in patients of Meniere's disease.

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Harmonic acceleration tests in the yaw plane with the head centered or in an eccentric position 90cm from the axis of rotation were performed in 41 patients with unilateral canal paresis due to vestibular neuronitis and sudden deafness, Meniere's disease and benign paroxysmal positional vertigo (BPPV). In the eccentric at 0.32 and 0.6Hz, gain enhancement and phase lead were observed in the normal subjects. In the eccentric , subjects were stimulated both by angular acceleration, as well as linear centrifugal and tangential acceleration, which act on the otolith organs. At 0.32 and 0.64Hz in this position, tangential acceleration showed a higher value than centrifugal acceleration. Therefore, we concluded that the gain enhancement and phase lead in the eccentric were derived from tangential acceleration acting on the utriculus.
The patients with vestibular disorders other than BPPV showed normal gain enhancement and phase lead at 0.32 and 0.64Hz. However, patients with BPPV, showed no gain enhancement or phase lead in 53.3% and 73.3% of the patients, respectively.
It is suggested that BPPV results from incorrect response of the cupola in the posterior semicircular canal to gravitational changes due to otolithiasis. Therefore, the loss of gain enhancement and phase lead in the eccentric in the patients with BPPV may be the result of utricular dysfunction.

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Single sideband (SSB) doppler VHF omnidirectional radio range (D-

) has been widely used as a short-range air navigational system. While, double sideband (DSB) D- has superior performances with respect to siting effects, course stability and a compatibility with present receiving equiment, when compared to the SSB D-. Accordingly, the DSB D- has been adopted as a standard in Japan.

However, the operational efficiency of

system has been depreciated owing to lack of stability of ordinary monitor functions. On one hand, when the monitoring location of DSB D- is close to the station, a distortion of the detected signal largely rises with the distance approaches. On this account, there are some cases where sufficient monitor performance cannot be obtained by the usual monitoring system.

In order to eliminate these defects, it is worked out a new

monitoring system which is composed of a receiver with automatic gain control (AGC) amplifier, antenna breakdown detector and near field monitor with carrier phase compensation technique.

This paper describes improvements of the monitoring system for DSB D-

, and the results of the operational tests are presented.

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Doppler

has an improvement with respect to siting effects compared to the conventional , although the Doppler is costly to install.

SSB Doppler

is preferred to be operated because of simple and low cost construction, but the SSB Doppler has the systematic bearing error caused by undesired amplitude modulation which results from the rotating sideband antenna pattern distorted by the counterpoise.

This paper describes an analytical study on the systematic error sources and the error reduction methods by means of compensating signal radiation.

The summary flight test results are also presented and discussed in relation to the effectiveness of the error reduction method.

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A Furosemide test was performed on 41 patients with typical Meniere's disease,21 with atypical Meniere's disease,13 with delayed endolymphatic hydrops and 6 with syphilitic labyrinthitis.
Twenty-five of the 41 patients (61%) with typical Meniere's disease were evaluated as being abnormal by this test. Even more patients (91%) were judged to be abnormal when results of the furosemide test were combined with those of the glycerol dehydration test or transtympanic electrocochleography, which suggests that a combination of these tests may be useful in diagnosing endolymphatic hydrops of typical Meniere's disease.
Twelve of the 21 patients (57%) with atypical Meniere's disease showed abnormal results in both the furosemide test and caloric test. Eight of 13 patients (62%) with delayed endolymphatic hydrops and 3 of 6 (50%) with syphilitic labyrinthitis also had positive results. These findings suggest that this test may be useful for checking endolymphatic hydrops of the vestibular system of the inner ear not only for typical Meniere's disease but also for dizziness.

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This report describes the mechanism of bearing fluctuation in Doppler

(DVOR) by sea surface reflection in order to present an expression for predicting the magnitude of the fluctuation.

Intrinsic bearing error in DVOR is noted to explain the phenomenon. The influence of sea surface reflection on the intrinsic bearing error is analyzed by observing the radiation pattern of DVOR antenna. Then, it has been shown that the bearing fluctuation is caused by the variation of intrinsic error by sea surface reflection. We have assumed that the expression for the intrinsic error may be directly applied to predict the bearing fluctuation.

Flight experiment was performed for several VORs to measure the bearing and signal level. A good agreement between measured and computed results, observed in most VORs, has proved the validity of our assumption. An example is also presented in which measured result did not agree to the computed one. Experimental study has shown that this discrepancy is caused by excessive attenuation of signal level at a null point and that our expression is applicable even in the case by making a slight modification.

The analysis has shown that the magnitude of bearing fluctuation may be reduced if DVOR antenna is designed to reduce intrinsic bearing error, by extending the size of counterpoise for example, because the bearing fluctuation is directly linked to the intrinsic error.

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DSB Doppler

has the advantage in reducing the siting effects and bearing errors as compared to conventional and SSB Doppler , and adoption of DSB Doppler is being considered in Japan.

The performance test have been carried out on the course characteristics and the stability of the system utilizing the Antenna Test Tower in the Electronic Navigation Research Institute and at Choshi, east of Tokyo.

This paper describes an analytical study on some operational problems in DSB Doppler

and its performance test results.

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Doppler VHF Omnidirectional Range (DVOR) has an intrinsic bearing error caused by its antenna system. This paper presents a general formula which can predict the error not only in SSB DVOR but in DSB DVOR. Mutual coupling among antenna elements is mainly studied since the error in the DSB DVOR may be created by the phenomenon.

Experiment was performed to determine the antenna current induced by the mutual coupling. An expression is developed for predicting the error by the current. The expression is integrated with the formulas which can represent the bearing error caused by the influence of the counterpoise and distributor.

Some numerical results are presented and compared with measured ones obtained by the experiment on the Antenna Test Tower. The comparison demonstrates the validity of the integrated formula.

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Shelterization of

/DME and ILS equipments were planned in order to shorten the construction period, and to obtain high reliability and high maintenability and standardization of the equipments.

During the development, extensive new design and modification work were made based on the results of various tests and evaluation, and finally we succeeded in modernizing sheltered navigational aid equipments by accumulating these works.

Results show that, approximately 20 dB less noise was recorded in the DME equipment and the temperature was kept at a reasonably comfortable level in the shelters even when the outside temperature was 40°C. The construction period at the site is shortened to approximately 3 months as compared to 10 months of the former types.

The sheltered equipment has already been installed at various sites and the JCAB has additional installation plans of the sheltered navigational aid equipments.

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