A new method for analyzing smooth-pursuit eye movements
Tóm tắt
The study of ocular movements has been increasingly used to detect subtle pathological modifications, caused by a wide variety of neurological diseases. We have developed a new microcomputer-based method for the analysis of smoothpursuit ocular movements induced by constant velocity targets moving unpredictably at different velocities (including velocity values as high as 100 deg/s). The ocular movements are recorded by an electro-oculographic technique using silversilver chloride electrodes fixed near the inner and outer canthi of both eyes. The signals are amplified by two DC amplifiers after a low-pass filtering (50Hz), sampled at 250 Hz and digitized in a 12-bit form by an analog/digital converter. For each patient's evaluation, a series of 20 sweeps of the target is generated. The data analysis, which is performed automatically by the microcomputer, is based one the calculation of four parameters: average peak eye velocity (APEV); typical target velocity (TTV); percent target matching index after saccade removal (PTMI); typical matching target velocity (TMTV) after saccade removal. APEV is calculated as the average of the peak velocities estimated from the 20 sweeps. The purpose of TTV, which is defined as the value of target velocity at which the percent gain has decreased to slightly more than one third of the maximum percent gain, is to provide an overall index of the rate at which the percent gain decreases as the target velocity increases. PTMI describes the eye performance for each value of target velocity. TMTV, which represents the target velocity at which the PTMI has decreased to approximately 37%, is an overall index of the rate at which the PTMI decreases as the target velocity increases. This parametrization of smooth pursuit has been tested in 28 healthy volunteers and in one patient with a neurological disease. Our results indicate that our method can provide a reliable and quantitative parametrization of smooth pursuit.
Tài liệu tham khảo
Abel L.A., Hertle R.W.:Effects of psychoactive drugs on ocular motor behavior. In (Johnston C.W. and Pirozzolo F.J. Eds) Neuropsychology of eye movements. Lawrence Erlbaum Associated Publishers, Hillsdale, New Jersey, pp. 177–200, 1988.
Avanzini G., Girotti F., Caraceni T., Spreafico E.:Oculomotor disorder in Huntington's chorea. J. Neurol Neurosurg Psychiat, 42:581–589, 1979.
Avanzini G., Girotti F., Crenna P., Negri S.:Alterations of ocular motility in cerebellar pathology. An electrooculographic study. Arch Neurol. 36:274–280, 1979.
Baloh R.A., Jenkins H.A., Honrubia V., Yee M.D., Clkifford G.Y.:Visual-vestibular interaction and cerebellar atrophy, Nature, 29:116–119, 1979.
Bittencourt R.P., Gresty M.A., Richens A.:Quantitative assessment of smooth pursuit eye movement in healthy and epileptic subjects. J. Neurol Neurosurg Psychiatry 43:1119–1124, 1980.
Buizza A., Avanzini P.:Computer Analysis of Smooth Pursuit Eye Movements. In (Groner R., Menz C., Fisher D.F.; Eds.: Eye Movements and Psychological function: international views. Lawrence Erlbaum Ass. Publisher London, 1983:7–18.
Buizza A., Schmid R.:Velocity characteristics of smooth pursuit eye movements to different patterns of target motion. Exp Brain Res, 63:395–401, 1986.
Cipparrone L., Gianneschi F., Degl'Innocenti F., Porzio P., Pagnini P., Marini P.:Electro-oculographic routine examination in Parkinson's disease. Acta Neurol Scand, 77:6–11 1988.
Estanol B., Lopez-Rios G.:Neuro-otology of the lateral medullary infarct syndrome. Arch Neurol, 39:176–179, 1982.
Fletcher W.A., Sharpe J.A.:Smooth pursuit dysfunction in Alzheimer's disease. Neurology, 38:272–277, 1988.
Gangemi P.F., Messori A., Baldini S., Parigi A., Massi S., Zaccara G.:Comparison of two nonta. Comput Prog Biomed, 34:291–297, 1991.
Gibaldi M., Perrier D.:Pharmacokinetics. New York, Dekker, 1982.
Inchingolo P., Spanio S.:On the identification and analysis of saccadic eye movements—A quantitative study of the processing procedures. IEEE Transaction on Biomedical Engineering, 32:683–695, 1985.
Kennard C., Lueck C.J.:Oculomotor abnormalities in diseases of the basal ganglia. Rev Neurol, 145, 587–595, 1989.
Leigh R.J., Tusa R.J.:Disturbance of smooth pursuit caused by infarction of occipitoparietal cortex. Ann Neurol, 17:185–187, 1985.
Lisberger S.G., Morris E.J., Tychsen L.:Visual motion processing and sensory-motor integration for smooth pursuit eye movements. Ann Rev Neurosci, 10:97–129, 1987.
Meyer C.H., Lasker A.G., Robinson D.A.:The upper limit of human smooth pursuit velocity. Vis Res, 34:561–563, 1985.
Robinson D.A., Gordon J.L., Gordon S.E.:A model of the smooth pursuit eye movement system. Biol Cybern, 55:43–57, 1986.
Rothenberg S.J., Selkoe D.:Specific oculomotor deficit after diazepam. II. Smooth Pursuit Eye Movements. Psychopharmacology, 74:237–240, 1981.
Sharpe J.A., Silvester T.O.:Effect of aging on horizontal smooth pursuit. Invest Ophthalmol Vis Sci, 17:465–468, 1978.
Spooner J.W., Sakala S.M., Baloh R.W.:Effects of aging on eye tracking. Arch Neurol, 37:575–576, 1980.
Takahashi M., Uemura T., Fujishiro T.:Quantitative analysis of pursuit eye movements by unidirectional target motion. Arch Oto-Rhino-Laryngol, 238:225–232, 1983.
Tedeschi G., Bittencourt P.R., Smith A.T., Richens A.:Specific oculomotor deficits after amylobarbitone. Psychopharmacology, 79:187–189, 1983.
Troost B.T., Daroff R.B.:The ocular motor defects in progressive sopranuclear palsy. Ann Neurol, 2:397–403, 1977.
White O.V., Saint-Cyr J.A., Tomlinson R.D., Sharpe J.A.:Ocular motor deficits in Parkinson's disease. Brain, 106: 571–587, 1983.
Young L.R.:Pursuit eye tracking movements In: Bach-y-Rita P., Colling C.C., Hyde J.E., (Eds) The control of eye movements. Academic Press, New York, 1971:429–443.
Zaccara G., Gangemi P.F., Baldini S., Messori A., Muscas G.c., Pallanti S., Arnetoli G.:Smooth-pursuit alterations in Alzheimer's disease. Prooceedings of the Fifth European Conference on Eye Movements 1989:315–317.
Zee D.S., Yee R.D., Cogan D.G., Robinson D.A., Engel D.:Ocular motor abnormalities in hereditary cerebellar ataxia. Brain, 99:207–234, 1976.