Coordination of the extraocular recti muscles in the cat.

With the use of multiple implanted electrodes in chronic preparations, the electromyograph of the spontaneous activity of the extraocular muscles has been studied in the unanesthetized and unrestrained cat. Simultaneous strain gauge records were also made for monitoring eye movement in acute, restrained preparations with the use of local anesthesia only. It was found that there was a constant ongoing activity in all extraocular muscles as long as the cat was awake. This constant activity increased with arousal or with attention. Most eye movements in the cat were largely saccadic of only a few degrees of arc and were signalled by only a short differential burst of activity. Inhibition of activity was recorded mainly during extreme deviation of gaze. The electromyographic records of eye movement in the cat were found to be conveniently divided into four classifications: classical reciprocal innervation; an increased activity of agonist only; a simple decrease in activity of antagonist only; or cocontraction, with only a slightly greater burst of activity discernible in the shortening muscle.