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Biomedical subjects

W Bles

Publications and source records attributed to W Bles.

18 recordsLinked to original sources
PubMed1992

A new autosomal dominant syndrome of idiopathic progressive vestibulo-cochlear dysfunction with middle-age onset.

A kindred is described with progressive autosomal dominant vestibulo-cochlear dysfunction resulting in instability in the dark, head movement dependent oscillopsia and hearing loss. The first symptoms appeared in the 4th decade and progressed to vestibular areflexia, presumably in the 5th decade and to almost total deafness in the 6th-7th decade of life. The history was negative for other neurological, otological or infectious diseases, or the use of neuro-ototoxic drugs. The affected subjects showed remarkable compensation for the loss of vestibular function.

Aged↗
PubMed1992

Influence of visual, vestibular, cervical, and somatosensory tilt information on ocular rotation and perception of the horizontal.

By combining a tilting chair and a tilting room we investigated the subjective horizontal (SH) and ocular counterrotation (OCR) as a function of body tilt, trunk tilt, and tilt of a visual frame. Significant influences of (isolated or combined) vestibular and visual information were found, but no influence of neck proprioception. A second and similar experiment, however, now conducted with subjects devoid of labyrinthine function, suggested a contribution of the neck as well as of somatosensory origin. This made a reinterpretation of our data for normal subjects possible.

Adult↗
PubMed1991

The Aubert-Fleischl paradox does appear in visually induced self-motion.

An experiment was set up to investigate the possible influence of oculomotor activity on experienced speed of circular vection. With the standard lined inner wall of an optokinetic drum as stimulus, we found that subjects, sequentially exposed to periods with or without fixation point, experienced an increment in speed of circular vection when the eyes were kept stationary as compared to when optokinetic nystagmus occurred. In a control condition, however, where the influence of optokinetic nystagmus vs fixed gaze on the speed of circular vection was measured separately, the effect was not significant. These findings might explain a discrepancy found in the literature.

Adult↗
PubMed1991

Ocular rotation and perception of the horizontal under static tilt conditions in patients without labyrinthine function.

In a previous study (1) it was found that in healthy subjects Ocular (Counter) Rotation is mainly due to otolith stimulation and only to a minor extent induced by slanted visual structures. Stimulation of the neck by tilting the trunk laterally upwards did not result in a systematic rotation of the eyes. In the present study it was found that subjects with bilateral loss of vestibular function showed a higher visually induced ocular rotation. Tilting the head (cervical stimulation) or the whole body (somatosensory stimulation) also led to a considerable OCR, demonstrating substitution of other sensory modalities for the loss of vestibular function. Estimates of the subjective horizontal were noisy, demonstrating the lack of an adequate gravitational reference signal.

Ear, Inner↗
PubMed1991

The tilting room and posturography.

The tilting room examination technique is detailed. The advantages of posturography with the tilting room as an additional tool in the clinical vestibular examination are described for patients with uni- and bilateral loss of vestibular function, for patients with an acoustic neurinoma and for patients suffering from cervical ataxia. Some illustrations are also given of other applications of the tilting room.

Ataxia↗
PubMed1990

Angular velocity, not temporal frequency determines circular vection.

This paper shows that the experienced speed of circular vection depends on stimulus speed, not on stimulus temporal frequency. But why would anyone think the contrary? The point is that many modelers in the field of motion perception believe that perceived speed is determined by temporal frequency. Moreover, the optokinetic behaviour of the fly is said to be dependent on the temporal frequency, not the speed, of the stimulus pattern (Reichardt, 1987). It was the aim of the present experiment to test the notion that the experienced speed of circular vection is proportional to stimulus velocity information, which is carried by the temporal and the spatial characteristics of light.

Adult↗
PubMed1989

Performance and well-being under tilting conditions: the effects of visual reference and artificial horizon.

It is generally agreed that the incidence of motion sickness in sailors working below deck is higher than in sailors who have the horizon as a visual reference on the bridge. This study investigated the possible beneficial effect of a projected artificial horizon as a means to prevent seasickness. Twelve subjects were exposed to angular motion in a tilting room under three experimental conditions: a) With the windows covered, allowing no visual reference from the outside world; b) With the windows uncovered, thus allowing a partial view of the environment; and c) With the windows covered and a horizon projected on the walls by a rotating laser beam. Subjects were exposed for 35 min in each condition while performing different computerised tasks. There was a reduction in well-being and performance as a function of exposure time. These effects were clearly shown in the "closed cabin" condition. There were less motion sickness symptoms in the "artificial horizon" and "window" conditions. The presence of a visual reference prevented the decrement in performance found in the "closed cabin" condition. The results of this study suggest that a projected horizon might alleviate motion sickness aboard naval vessels, and thus improve the performance of sailors at sea.

Female↗
PubMed1979

Height vertigo and human posture.

A theory is presented supporting a geometrical explanation for physiological height vertigo being a distance vertigo through visual destabilization of postural balance when the distance between the eyes and visible stationary contrasts becomes critically large. Physiological and posturographic data obtained under natural height vertigo conditions are consistent with this hypothesis.

Humans↗