Labyrinthine Defects Research Articles

Sonic hedgehog through Gli2 and Gli3 is required for the proper development of placental labyrinth.

Sonic hedgehog (Shh) functions as a conserved morphogen in the development of various organs in metazoans ranging from Drosophila to humans. Here, we have investigated the potential roles and underlying mechanisms of Shh signaling in murine placentation. Immunostaining revealed the abundant expression of the main components of Shh pathway in both the trophectoderm of blastocysts and developing placentas. Disruption of Shh led to impaired vascularogenesis of yolk sac, less branching and malformation of placental labyrinth, thereby leading to a robust decrease in capacity of transplacental passages. Moreover, placenta-specific gene incorporation by lentiviral transduction of mouse blastocysts and blastocyst transplantation robustly knocked down the expression of Gli3 and Gli2 in placenta but not in embryos. Finally, Gli3 knockdown in Shh−/− placentas partially rescued the defects of both yolk sac and placental labyrinth, and robustly restored the capacity of transplacental passages. Gli2 knockdown in Shh+/− placentas affected neither the capacity of tranplacental passages nor the vascularogenesis of yolk sac, however, it partially phenocopied the labyrinthine defects of Shh−/− placentas. Taken together, these results uncover that both Shh/Gli2 and Shh/Gli3 signals are required for proper development of murine placentas and are possibly essential for pregnant maintenance.

Effects of optokinetic stimulation induced by virtual reality on locomotion: a preliminary study

Conclusions. Exposure to a virtual environment for 20 min was sufficient to cause adaptive changes in locomotion in healthy subjects, suggesting that virtual environments might improve locomotor deviation in patients with unilateral labyrinthine defects. Objective. Postural and locomotor control in patients with unilateral labyrinthine defects deviates towards the lesion side. The aim of this study was to examine whether active locomotion within a virtual environment can increase the functionality of rehabilitation. Subjects and methods. We examined the effects of optokinetic stimulation produced by a virtual reality environment on ocular movement and locomotor tracks in 10 healthy subjects. Results. During the 20 min experiment, the mean locomotor deviation and the mean frequency and mean amplitude of optokinetic nystagmus during the last period of the experiment were significantly higher than those during the initial period.

Interaction between Ocular Stabilization Reflexes in Patients with Whiplash Injury

In the past few decades, the automobile has become an increasingly more popular means of transport, which has led to an increasing number of rear-end collisions and consequently has resulted in more patients with whiplash-associated disorders (WADs). Recently, it was found that the gain of one of the ocular stabilization reflexes-the cervico-ocular reflex (COR)-is elevated in patients with whiplash injury. The COR responds to proprioceptive signals from the neck and acts in conjunction with the vestibulo-ocular reflex (VOR) and the optokinetic reflex (OKR) to preserve stable vision on the retina during head motion. Therefore, an investigation was conducted to determine whether the reported elevation of the COR in WADs is accompanied by changes in VOR or OKR. Eye movements of 13 patients and 18 age-matched healthy controls were recorded with an infrared eye-tracking device. Analysis confirmed a significant increase in COR gain in whiplash patients. Meanwhile the VOR and OKR gains remained the same. No correlation was found between the gains of the reflexes in individual patients. This is in contrast to earlier observations in elderly subjects and subjects with labyrinthine defects, who showed increases in COR gain and decreases in VOR gain. Impaired neck motion, altered proprioception of the neck, or disorganization in the process of VOR plasticity could explain the lack of change in VOR gain.

Short Nystagmus Duration of Velocity Step Response as an Indicator of Labyrinthine Defects

The nystagmus response elicited by a velocity step of 90 degrees/s was evaluated in a group of 500 consecutive patients by computer analysis and by measuring the duration (t, in s) of the first phase of the response. A 90% log normal range of 37-55 s (mean 45 s) was established for t directly from the electronystagmogram (ENG) in a group of 12 normal subjects. The computer-based response type 'G-', i.e. 'Gesamtamplitude' (cumulative eye displacement), G less than 480 degrees, yielded a detection rate of labyrinthine defects (LDs) of about 65% with 35% false positives and 15% false negatives. A percentage of only about 25 of LDs was detected, with similar percentages of false detections, when using a criterion based on short t values. The lower yield was partly due to the fact that in some 35% of the cases t could not be measured; in the evaluable cases alone, the detection rate was 60% when using the G criterion and 50% when using the t criterion. It is recommended to measure G directly from the ENG, if t is too short or not available, whenever diminished vestibular responses are suspected.

Diagnostic Value of Velocity-Step Responses

For the nystagmic (after-)response in each direction it was evaluated in 618 patients whether the gain (initial velocity) and the time constant were normal, significantly low or high, thus constituting a specific 'response pattern'. In a number of diagnostic categories, 65% of the response patterns were 'typical', i.e., they were found in significantly high frequency. Symmetrical response patterns were predominant. Short time constant(s) and/or low gain values in either or both directions were found in labyrinthine defects. High gain values were found in otosclerosis after footplate surgery, in multiple sclerosis, hyperventilation syndrome, posterior fossa tumour and spasmodic torticollis. In those categories, except otosclerosis and posterior fossa tumour, also significantly high values of the time constant were found, as well as in the category of patients with exposed tympanic cavity and dizziness. A significant directional preponderance indicating the defective side was found for the low-frequency gain (i.e., the product of initial velocity and time constant) in 48% of the patients with unilateral canal paralysis. It is concluded that the velocity-step test is a powerful diagnostic tool in vestibular examination.

Compensation for labyrinthine defects examined by use of a tilting room.

Visual compensation for vestibular deficiency was demonstrated by stabilometry inside a laterally tilting room. Labyrinthless patients showed a predominance of vision over the somatosensory system for a rather long time: in contrast to the controls, the labyrinthless subjects experienced the tilting room often as stationary and the stationary stabilometer as tilting, which resulted in vertical postural instability.

Labyrinthine Defects as Shown by Ataxia and Caloric Tests

Most of the individuals with labyrinthine defects severe enough to produce ataxia test performance scores within the lowest 5% of the normal distributions also showed threshold caloric test responses which fell within the same range. Similarly, almost as many individuals with decreased threshold caloric test responses also showed poor ataxia test performance scores. While vestibular influences governing threshold caloric test responses are far more specific than those affecting results on the ataxia tests, the high agreement shown between results of each in groups of individuals with various loss or disturbance of labyrinthine function implies a common vestibular effect to a considerable degree.

Symptomatology under storm conditions in the North Atlantic in control subjects and in persons with bilateral labyrinthine defects.

Ten labyrinthine defective (L-D) and twenty normal subjects were exposed to extremely severe weather conditions during a sea voyage. The effects of such a stress were complicated by a feeling of fe...

The effect of water immersion on perception of the oculogravic illusion in normal and labyrinthine-defective subjects.

The separate and combined influences of otolith and nonotolith sensory inputs upon perception of the oculogravic illusion were investigated by manipulating the visual and gravitoinertial force environments. By comparing the visually perceived direction of space by four naval aviators and four deaf persons with bilateral labyrinthine defects when dry and when immersed in water up to neck level, the contributions of (1) field force receptors in the vestibular organs and (2) nonvestibular proprio-ceptors stimulated by external contact support could be differentiated. Under these various conditions it was found that in normal persons, the vestibular contribution is predictable in terms of the direction of the gravitoinertial force vector but that the nonvestibular contribution varies; it may be relatively great or small. In persons with bilateral labyrinthine defects a nonvestibular contribution was always present but there was great individual variance. The significance of the findings in terms of tests meas...

Sympatho-adrenomedullary activity during experimentally provoked mental stress in patients with labyrinthine defects.

The effect of psychological stimuli on sympatho-adrenomedullary activity as reflected in the urinary excretion of catecholamines was studied in 19 volunteers with normal labyrinthine function, and in 20 Meniere patients with single or bilateral labyrinthine defects. In the normal subjects, experimentally induced emotional stress was accompanied by a significantly increased excretion of urinary catecholamines. This was not the case in the patients with unilateral labyrinthine dysfunction; their adrenaline excretion declined throughout the experiment. In three patients with bilateral labyrinthine destruction the adrenaline excretion remained very low throughout the experiment, and the emotional stress was not accompanied by the rise found in the healthy subjects.

Perception of Orientation: Adaptation to Lateral Body-Tilt

* Received for publication July 19, 1965. This study, undertaken at Clark Uni, versity, was supported by USPHS Research Grant MH-00348 from the National Institute of Mental Health. 'Kurt Koffka, Principles of Gestalt Psychology, 1935, 218; J. J. Gibson and 0. H. Mowrer, Determinants of the perceived vertical and horizontal, Psychol. Rev., 45, 1938, 300-323; H. A. Witkin and S. E. Asch, Studies in space orientation: IV. Further experiments on perception of the upright with displaced visual fields, J. exp. Psychol., 38, 1948, 762-782; C. W. Mann, N. H. B. Berry, and H. J. Dauterive, The perception of the vertical. I. Visual and non-labyrinthine cues, J. exp. Psychol., 39, 1949, 538-547; Gibson, The relation between visual and postural determinants of the phenomenal vertical, Psychol. Rev., 59, 1952, 370-375; Heinz Werner and Seymour Wapner, Sensory-tonic field theory of perception: Basic concepts and experiments, Rev. Psicol., 50, 1956, 315-337; K. A. Chandler, The effect of monaural and binaural tones of different intensities on the visual perception of verticality, this JOURNAL, 74, 1961, 260-265; Brant Clark and Ashton Graybiel, Perception of the postural vertical in normals and subjects with labyrinthine defects, J. exp. Psychol., 65, 1963, 490-494. 2 H. E. Burtt, The perception of slight changes of equilibrium, with especial reference to problems of aviation, J. appl. Psychol., 2, 1918, 101-115; P. M. van Wulfften Palthe, Function of the deeper sensibility and of the vestibular organs in flying, Acta Otolaryng., 4, 1922, 415-449; L. H. Bauer, Dangers of high speed and acrobatic flying, Aviation, 16, 1924, 174-176; F. Leiri, Ober die Bedeutung des Vestibularapparats bei der aviation, Z. Hals-Nasen-, und Ohrenh-lk., 17, 1927, 381391; A. Gemelli, L'orientazione lontana vel volo in aeroplane, Riv. Psicol., 29, 1933, 297-325; Witkin, Perception of body position and of the position of the visual field, Psychol. Monogr., 63, 1949, (No. 302), 1-46; Perception of the upright when the direction of the force acting on the body is changed, J. exp. Psychol., 40, 1950, 93-106; J. H. McFarland, Seymour Wapner, and Heinz Werner, Relation between perceived location of objects and perceived location of one's own body, Percept. mot. Skills, 15, 1962, 331-341. 3Witkin, op. cit., 1949, 1-46; Mc Farland, Visual and proprioceptive changes during visual exposure to a tilted line, Percept. mot. Skills, 15, 1962, 322.

PERCEPTION OF THE POSTURAL VERTICAL FOLLOWING PROLONGED BODILY TILT IN NORMALS AND SUBJECTS WITH LABYRINTHINE DEFECTS.

Nine normal men and ten men with defective labyrinthine function were studied in order to determine the effects of prolonged bodily tilt on their perception of the postural vertical. The subjects were tested under two conditions of delay before setting themselves to vertical and four degrees of tilt. A 2 × 2 × 4 analysis of variance showed significantly greater average errors for the labyrinthine defective men, for prolonged delay in recovery to vertical, and for the larger tilts.

A COMPARISON OF OCULAR COUNTER-ROLLING MOVEMENTS BETWEEN NORMAL PERSONS AND DEAF SUBJECTS WITH BILATERAL LABYRINTHINE DEFECTS.

A COMPARISON OF OCULAR COUNTER-ROLLING MOVEMENTS BETWEEN NORMAL PERSONS AND DEAF SUBJECTS WITH BILATERAL LABYRINTHINE DEFECTS.

Perception of the postural vertical in normals and subjects with labyrinthine defects.

Visual perception study of postural vertical in normals and subjects with vestibular defects