Biomedical subjects
Publications and source records attributed to C Menguy.
The authors, using rotatory visual and vestibular stimulators, propose to perform an experiment to study the effect of long periods of weightlessness on vestibular and visual interactions in frogs. The results will be analysed within the Framework of sensory conflict theory. Preliminary experiments are in progress in order to determine the best method for containments of long duration.
This project has developed so as to include the total range of electroretinographic responses under conditions of space flight. We built two special containers which made stratospheric balloon flights. The second prototype carries the following specifications: Immobilisation of two frogs; Light stimulation by flashes; Special corneal electrodes; Amplification and recording system. There is almost no tissue damage after prolonged observation (several days) of the animals and the electroretinographic responses do not show any significant changes. Such an apparatus could be used as the basis for an assembly to be incorporated into Spacelab.
The effects of ocular fixation on per-rotatory nystagmus were studied during the course of the pendular vestibular stimulation test. If the subject is normal, or the disorder is peripheral, the nystagmus is abolished. Examples of these different results are presented.
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During vestibular function tests using the pendulum chair, electronystagmography has repeatedly shown that a tonic ocular deviation precedes the change in nystagmus. This tonic movement may be anticipated in respect to the change in the sinusoidal movement of the chair. Greiner, Conraux, Collard and more recently J.B. Causse, have proposed a hypothesis based on the own periodicity of the vestibular system. J. Max explained this phenomenon in terms of a difference in phase with the electronic system. Our investigation suggests another explanation of this phenomenon. Each half-period consists of a acceleration phase and a decelaration phase. Thus within half-period alone there are two successive forms of nystagmus induced. The succession of half-periods gives the usual systagmus response. We consider that the tonic response of the eyes is not an anticipated one in respect to the change in sinusoidal movement of the chair, but rather a delayed one in respect to the reversal in the direction of acceleration.
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Explore the source record for details and available documents.