202 



Scientific Proceedings (108). 



i 08 (1568) 



Observations on the physiology of the otic labyrinth. The 

 influence of prolonged rotation on the duration of post- 

 rotatory nystagmus. 



By Alexander L. Prince. 



[From the Physiological Laboratory, Yale School of Medicine, 

 New Haven, Conn.] 



Rotation of the head in space is accompanied by ocular move- 

 ments of a definite type. These ocular movements (nystagmus) 

 present two phases: a slow deviation of the eyes opposite to the 

 direction of rotation, followed by a quick return to the initial 

 position. 



On cessation of rotation similar movements are observed. 

 In the post-rotatory nystagmus, however, the slow deviation 

 phase is in the direction of the preceding rotation. 



The deviation phase as shown by Wilson and Pike 1 is dependent 

 on labyrinthine stimulation whereas the quick return is due to a 

 proprioceptor reflex arising from the stretched antagonist ocular 

 muscle during the deviation phase. These ocular movements 

 can be especially well studied in the post-rotatory period. 



The duration of the post rotatory nystagmus is dependent on the 

 intensity of the labyrinthine stimulus and therefore on the speed 

 of rotation and up to a certain point on the number of revolutions 

 at any given speed. Using a standard of ten turns in twenty 

 seconds, the duration of post rotatory nystagmus in man has 

 been utilized as an index of labyrinthine efficiency. 



This test has been applied extensively in the examination of 

 candidates for the U. S. Aviation Service. 



The post rotatory nystagmus under the standard rotation test 

 has an average duration of 23 seconds. This figure is based on a 

 large number of determinations made by investigators in the oto- 

 logical department of the Air Service. 2 On the other hand, accord- 

 ing to members of the psychological department of this Service 2 



1 Wilson and Pike, Philosophical Transactions of the Royal Society, London, 1912. 

 Series B, CCIII. 127. 



2 Manual of the Medical Research Laboratory, War Department, Air Service, 

 Division of Military Aeronautics, Washington, D. C. 



