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Biomedical subjects

M Gavin

Publications and source records attributed to M Gavin.

23 records · Page 2Linked to original sources
PubMed1979

Modifications of vestibulo-ocular reflex induced by diazepam: experiments in the macaque.

The vestibulo-ocular reflex in the macaque was tested before and after intravenous administration of diazepam. The drug effect was marked by decrease in gain and increase in time constant of nystagmus in response to a modified Bárány test and by reduction in directional asymmetry of nystagmus. Because the time course of reduction in gain differed from the time course of increase in time constant, diazepam probably has more than one site of action. These results emphasize the complexity of neural processing in the vestibulo-ocular reflex arc.

Animals↗
PubMed1979

Modification of the macaque's vestibulo-ocular reflex after ablation of the cerebellar vermis.

In macaque, the vestibulo-ocular reflex (VOR) as evaluated by the time constant of nystagmus in a modified Bárány spinning test, shows a regular pattern of change with time after ablation of the vermis cerebelli. One day ablation the time constant is in the low normal range; it then increases, and after one week assumes values in the high normal range. While the time constant is high, the VOR is resistant to modification by repeated testing, but may be modified by unidirectional optokinetic nystagmus and by experience with reversing spectacles. These results suggest that the vermis of the cerebellum plays no crucial role in modifications of the VOR by visual inputs, but is involved when the VOR is modified by repeated vestibular experience.

Animals↗
PubMed1979

Response of the vestibulo-ocular reflex to differing programs of acceleration.

The vestibulo-ocular reflex of normal monkeys was tested by a modified Bárány spinning test (B-test) and by sinosoidal rotation. The two tests gave concordant estimates of the time constant and corner frequency. Deviation from concordance was caused largely by modification of the reflex during the testing procedures. As a means of estimating both time constant and corner frequency in the vestibulo-ocular reflex, the B-test is to be preferred to sinusoidal rotation because although both tests provide similar information, the B-test is the more rapidly performed and analyzed and the B-test modifies the reflex less.

Acceleration↗
PubMed1975

The nature of "spots" on soft lenses.

Of 278 consecutive therapeutic soft lens wearers, 19 (6.8%) developed discrete lens opacities on the anterior (air) surface of the lens. The incidence rose to 16.6% in patients fitted for dry eye syndromes, to 19% in bullous keratopathy and to 20% in exposure keratitis and trichiasis, if worn for longer than 2 weeks. These opacities were not associated with medications. Scanning electron microscopy demonstrated cracks on the anterior lens surface associated with these opacities. Transmission electron microscopy demonstrated the opacities to be amorphous material with extensions of the contact lens polymer into the substance of these opacities. Lipid, as demonstrated by histochemical methods, was found in these opacities. It is likely that the combination of dryness, stress on the lens surface, and lipid deposition act to alter the structure of the plastic and cause these opacities.

Calcium↗