A model of Alexander's law of vestibular nystagmus
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The observation that the amplitude of vestibular nystagmus grows as gaze is increased in the direction of the nystagmus fast phase and diminished with gaze in the opposite direction is known as “Alexander's law”. We have developed an analog computer model to simulate Alexander's law in nystagmus secondary to dysfunction of a semicircular canal. The model utilizes relevant brainstem anatomy and physiology and includes gaze modulation of vestibular signals and push-pull integration to create eye positition commands. When simulating normally functioning semicircular canals, the model produced no nystagmus. When simulating total impairment of the canal on one side with gaze directed maximally in the opposite direction, the model produced a large amplitude nystagmus with linear slow phases directed toward the affected side. As gaze was changed from far contralateral to ipsilateral, the nystagmus gradually diminished to zero. When simulating partial impairment of one canal, the nystagmus was smaller in amplitude and absent in ipsilateral gaze.
KeywordsOpposite Direction Computer Model Large Amplitude Analog Computer Slow Phasis
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- Alexander, G.: Die Ohrenkrankheiten im Kindesalter. In: Handbuch der Kinderheilkunde, pp. 84–96. Pfaudler, M., Schlossmann, A. (eds.). Leipzig: Vlg. F. C. W. Vogel 1912Google Scholar
- Barr, C.C., Schultheis, L.W., Robinson, D.A.: Voluntary, nonvisual control of the human vestibulo-ocular reflex. Acta Otolaryngol. 81, 365–375 (1976)Google Scholar
- Chun, K.S., Robinson, D.A.: A model of quick phase generation in the vestibuloocular reflex. Biol. Cybernetics 28, 209–221 (1978)Google Scholar
- Davidoff, R.A.: Synaptic transmission in the mammalian central nervous system. Weekly Update: Neurology and Neurosurgery 1, No. 24 (1978)Google Scholar
- Eccles, J.C.: The physiology of synapses. Berlin, Göttingen, Heidelberg, New York: Springer 1964Google Scholar
- Fernandez, C., Goldberg, J.M.: Physiology of peripheral neurons innervating semicircular canals of the squirrel monkey. IL Response to sinusoidal stimulation and dynamics of peripheral vestibular system. J. Neurophysiol. 34, 661–675 (1971)Google Scholar
- Melvill Jones, G.: Organization of neural control in the vestibuloocular reflex arc. In: The control of eye movements, pp. 497–518. Bach-y-Rita, P., Collins, C.C., Hyde, J.E. (eds.). New York, London: Academic Press 1971Google Scholar
- Robinson, D.A.: Oculomotor control signals. In: Basic mechanisms of ocular motility and their clinical implications, pp. 337–374. Lennerstrand, G., Bach-y-Rita, P. (eds.). Oxford, New York: Pergamon Press 1975aGoogle Scholar
- Robinson, D.A.: The neural basis for pontine and cerebellar control of eye movement. Jpn. J. Ophthalmol. 19, 25–38 (1975b)Google Scholar
- Young, L.R.: Role of the vestibular system in posture and movement. In: Medical physiology, pp. 704–721. Mountcastle, V.B. (ed.). Saint Louis: C. V. Mosby 1974Google Scholar