Optokinetic nystagmus was analyzed in ten normal subjects by superimposing a gaze point indicator on the image of moving objects. The foveal pattern of nystagmus was commonly elicited at stimulus velocities below approximately 60°/sec. The retinal pattern was observed at all rates. At low stimulus speeds, rudimentary forms of inadequate adjustment such as the waiting or overshooting forms appeared. These changed to the auxilliary or skipping forms of nystagmus, indicating direct influence of stimulus frequency on inadequate response. At high stimulus speeds, the foveal pattern of nystagmus was changed to an inadequate retinal pattern by the slowing of pursuit or the increasing of the degree of waiting.
Optokinetic stimuli were given to adult non-albino rabbits on alternate days and changes in optic eye and head nystagmus induced thereby were examined. The results were as follows: 1) The eye nystagmus responses gradually increased after repeated optic training by optokinetic stimulation, so that the velocity of cylinder rotation for inducing nystagmus at the maximum frequency could be raised and the upper limit of cylinder rotation which effectively induced nystagmus was raised. Head nystagmus appeared at a higher velocity of cylinder rotation after training and continued on more rapid cylinder rotation. 2) After the proprioceptors in either the deep or the superficial nuchal muscles had been inactivated by procainization, the animals were exposed to the same optic training. The phenomena described in 1) were seen less in these animals. This tendency seemed to be more evident in those rabbits in which the deep nuchal museles were procainized.
The isolation technique and response of the posterior semicircular canal in frogs were described. The spontaneous discharge from the ampullar nerve of the isolated posterior ampulla and its response to aspiration of the liquid within the canal (ampullofugal stimulation) were reported. A functional unit discharge from several nerve fibers of posterior ampullar nerve was found to increase with ampullofugal stimulation.
Under general anesthesia of chloralose-urethane, electric pulse trains were applied to the spinal nerves and dorsal roots in seventeen white adult rabbits. The induced eye movements were horizontal, directed to the side of stimulation. Activation or inhibition of eye muscles by the stimulation was exclusively limited to the lateral and medial rectus muscles. Contraction or relaxation of these muscles occurred with a latency as long as 40-60 msec or more. The effect was constant and strong from the first and the second cervical nerves, not constant from the third and absent from the levels below the fourth. It was constant from cervical and thoracic dorsal roots but not certain from lumbar or sacral levels. Despite its unusually long latency, the highly selective linkage of the spinal sensory nerves to the horizontal movers of the eyes may indicate that the reflex is based on a well organized integration of the nervous system. The spinal neck reflex on the eyes was inhibited by the cupulo-ocular reflex when both reflexes caused the eyes to deviate in the same direction, but was augmented when the reflexes caused deviation in opposite directions. This shows that inputs from the vestibulum and from the neck sensory nerves counteract each other in driving the eyes in the horizontal direction.
The otolithic membrane and the otoliths were studied light-microscopically by histological sections and surface specimens of the otolithic organs of the guinea pig. The otoliths were larger in the lower portion of the otolithic layer and smaller towards it's upper surface. However, in the stri ola, the narrow marginal zones, and the indented portion of the macula, the of oliths were very small and varied less in size. In the striola of the macula utriculi, the otolithic layer as a whole was thinner and it formed a concave groove on the surface of the otolithic membrane, while in the striola of the macula sacculi, the otolithic layer was thicker and formed a long series of hills. In the striola, the otolithic layer was generally nearer to the surface of the sensory epithelium than that in the other central part fo the maculae sacculi and utriculi.
In order to obtain information about eye movements in darkness including the rotatory component which cannot be recorded with electronystagmography, an infrared television apparatus was devised. The apparatus made it possible not only to observe eye movements in darkness in the same way as in light, but also to record the findings for future reference. The advantage of employing the infrared television was demonstrated by comparison between electronystagmograms and infrared television records. In the latter case, eye movements emerged as traces by frame-to-frame measurements of eye displacement on the monitor screen reproduced from the video recorder. Furthermore, measurements of ocular counterrolling in darkness were made in six normal subjects and the results obtained were compared with the counterrolling measured in light.
Diameters of the pupils were measured from photographs and by an infra-red television system. 123 cases of Meniere's disease (pathological group) and 71 normal subjects (normal group) were studied. The appearance rate of anisocoria was 22 to 29 per cent in the pathological group and 4.5 to 14 per cent in the normal group. The difference between the two groups was more significant following the cold pressor test or application of neosynephrine solution to the eye. Several possible causes of the findings were considered, and the correlation between the course of the attacks and the variations in the degree of anisocoria was studied. The results were used as a guide in classification, aniticipating prognosis and for reconsideration of the basic principles in the treatment of this disease. It was interesting to note that patients with Meniere's disease or migraine both often show anisocoria or abnormal pupillary reactions which may be ascribed to autonomic imbalances in the head and neck region.
It has been described that optokinetic disturbances are diminutions of nystagmus. However, the present authors noted that there was an abnormality showing hypernystagmus in optokinetic nystagmus of clinical cases. A cylinder was used in order to produce optokinetic stimuli. The cylinder was rotated electrically with angular acceleration of 2°/sec for 90 seconds. The resultant nystagmus was recorded by using an electronystagmograph. The ENG record during 90 seconds was divided every 10 seconds into 9 equal parts. A number of nystagmus beats and a mean slow phase eye-speed during each 10 seconds was measured. When the measured values of the number of nystagmus beats or the eye-speed exceeded the normal values, the optokinetic nystagmus was judged to be hypernystagmus. The lesion in the cases showing the optokinetic hypernystagmus were located in the visual apparatus, the cerebral cortex, the basal ganglia, the brain-stem and the labyrinth. Furthermore, it was stated that this optokinetic hypernystagmus was different from the optokinetic hypernystagmus associated with the development of optokinetic function.