Positional Nystagmus Elicited by Alcohol, Glycerin, or Heavy Water in the Rabbit

In unanesthetized rabbits, alcohol, glyserin, or heavy water was injected intravenously and nystagmic reaction elicited by passive alteration of body position was recorded by means of nystagmography, and the specific direction of the nystagmus was also observed. The following results were obtained 1. After Injection of alcohol (2.5~3.5ml/kg), right sloe down or lelf side down position elicited nystagmus in both eyes (FAN I) Right sloe down position elicited supero-dorsal nystagmus in the ipsilateral eye anti Infero-central nystagmus In the contralateral eye Left side down position produced nystagmus towards reversed directions 2. Returning to neutral position from one sloe down also elicited nystagmus towards the same direction. 3 From 5~6 hours after Injection of alcohol, the direction of the positional nystagmus was reversed, manifesting phase II of the PAN (PANII) 4. Injection of glycerin (2.0~3.0ml/kg) or heavy water (2.0~25ml/kg) also elicited positional nystagmus. The direction of the nystagmus was the same as and opposite to that Induced by alcohol Injection

Reflex Actions of the Anterior Semicircular Canals on the Clavotrapezius and Extraocular Horizontal Rectus Muscles in Cats

Electromyographic responses of the clavotrapezius and extraocular horizontal rectus muscles to the stimulations of the anterior semicircular canal nerves were observed to expore the funtional relationships between the canals and these canals muscles 1. The clavotrapezius muscle was inhibited stimulating the ipsilateral anterior canal nerve and excited by stimulating the contralateral anterior canal nerve. These responses were reversed by stimulating of the functionally paired posterior canal nerves. 2. During the clavotrapezius muscle responded to a prolonged stimulation of the ipsilateral anterior canal nerve, a superimposed stimulation of the contralateral anterior canal nerve reversed the initial response. 3. The medial rectus muscle was excited and the lateral rectus muscle was Inhibition by simulating the ipsilateral anterior canal nerve, and these responses were reversed by stimulating the contralateral canal nerve. Based on these results, it is concluded showing the functional connections between the receptor canals anti the effector muscles for the vestibuloocular and vestibulocollic reflexes, that the excitatory neural pathways from the vestibular nucleus to the cervical and ocular motoneurons are crossed to the opposite side, whereas the inhibitory from the nucleus to these axial motoneurons are uncrossed.