NYSTAGMUS RESPONSES DURING TRIANGULAR WAVEFORMS OF ANGULAR VELOCITY ABOUT THE Y- AND Z-AXES Lieutenant

Nystagmus response parameters were estimated by a test procedure using short triangular waveforms of angular velocity. Mean estimates were determined as follows: n/'A = 15.5 seconds and K n ( f /A) = 8.0 seconds for the horizontal semicircular canals, and [D/A= 6.8 seconds and Kn (8/A) = 5.4 seconds for the vertical semicircular canals. The N/'A values are consistent with results obtained by other methods. Values of K n (fl/A) have not been heretofore assessed. Determination of the effects of stimulus distortion on the values of the response parameters and estimates of intersubject and intrasubject variability are included. Also included are nomograms that permit a simple and accurate method for calculating ['L/A and K n (e/A). D D ,'°o% 1473 (PAGE 1 Uncla.i, fied ' ~ / t l 0 1 0 1 . 8 0 7 C ~ 8 0 1 S e c u r i t y C l a s s i f i c a t i o n Unclassified Security C l a s s i f i c a t i o n 14 . L INK A L INK B L INK C ROLE WT ROLE WT ROLE WT Aviation medicine Disorientation Magnetic field effects Motion sickness Radiation hazards Selection, training, and performance Space medicine Vestibular apparatus Vibration effects Bibllographies D D ,%%o1473 /BACK~ (PAGE 2) Unclassifled SOcurity C l a s s i f i c a t i o n Approved for public release; distribution unlimited. NYSTAGMUS RESPONSES DURING TRIANGULAR WAVEFORMS OF ANGULAR VELOCITY ABOUT THE YAND Z-AXES Lieutenant Richard D. Gilson, MSC, USNR, Captain Charles W. Stockwell, MSC, USAR, and Fred E. Guedry, Jr. Bureau of Medicine and Surgery M F 12.524.004-5001BX5G U. S. Army Aeromedical Research Laboratory Approved by Ashton Graybiel, M.D. Assistant for Scientific Programs Released by Captain N. W. Allebach, MC, USN Officer in Charge 22 July 1971 NAVAL AEROSPACE MEDICAL RESEARCH LABORATORY NAVAL AEROSPACE MEDI CAL I NSTITUTE NAVAL AEROSPACE MEDICAL CENTER PENSACOLA, FLORIDA 32512 SUMMARY PAGE THE PROBLEM In previous reports, parameters of the subjective semicircular canal reaction were estimated from responses to a series of test stimuli consisting of short triangular waveforms of angular velocity. In this report the feasibility of additlonal test procedures with short triangular waveforms that permit estimation of nystagmus response parameters is examined. FI NDI NGS Mean estimates of nystagmus response parameters were determined as follows: rb/~ = 15.5 seconds and K n (e /A ) = 8.0 seconds for the horizontal semicircular canals, and ~ / A = 6.8 seconds and K n (~/~) = 5.4 seconds for the vertical semicircular canals. Thes~ I'b/~ values are consistent with results obtained by other methods. Values of Kn (e /~) have not been heretofore assessed due to lack of a suitable method. Deterruination of the effects of stimulus distortion on the values of the response parameters and estimates of intersubject and intrasubject variabi l i ty are included. Also included are nomograms that provide a simple method for calculating ~/Z~and K n (e/Z~). ACKNOWLEDGMENTS The authors wish to express their appreciation to G. T. Turnipseed, J. W. Norman, and D. J. Gripka for their assistance in collecting and analyzing experimental data, and to Dr. Margaret Smith for her assistance with the statistical analysis.