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Eye position dependency of nystagmus during constant vestibular stimulation.


Bockisch, C J; Khojasteh, E; Straumann, D; Hegemann, S C A (2013). Eye position dependency of nystagmus during constant vestibular stimulation. Experimental Brain Research, 226(2):175-82.

Abstract

Alexander's law, the eye position dependency of nystagmus due to peripheral vestibular lesions, has been hypothesized to occur due to adaptive changes in the brainstem velocity-to-position neural integrator in response to non-reciprocal vestibular stimulation. We investigated whether it develops during passive head rotations that produce constant nystagmus for >35 s. The yaw rotation stimulus consisted of a 1-s acceleration (100°/s(2)), followed by a lower acceleration ramp (starting at 7.3°/s(2) and increasing at 0.04°/s(2)/s) until 400°/s was reached after 38 s. This stimulus was designed to offset the ~15 s vestibular ocular reflex time constant (and the 150 s adaptation time constant) and produce constant velocity slow phases. In contrast to peripheral lesions, this vestibular stimulation is the result of real head turns and has the push-pull characteristics of natural movements. The procedure was successful, as the average velocity of 31°/s was unchanged over the final 35 s of the acceleration period. In all 10 healthy human subjects, we found a large and stable Alexander's law, with an average velocity-versus-position slope of -0.366 in the first half that was not significantly different in the second half, -0.347. These slopes correspond to integrator time constants of <3 s, are much less than normal time constants (~25 s), and are similar to those observed in patients with peripheral vestibular lesions. Alexander's law also developed, on average, in 10 s. We conclude that Alexander's law is not simply a consequence of non-reciprocal vestibular stimulation.

Abstract

Alexander's law, the eye position dependency of nystagmus due to peripheral vestibular lesions, has been hypothesized to occur due to adaptive changes in the brainstem velocity-to-position neural integrator in response to non-reciprocal vestibular stimulation. We investigated whether it develops during passive head rotations that produce constant nystagmus for >35 s. The yaw rotation stimulus consisted of a 1-s acceleration (100°/s(2)), followed by a lower acceleration ramp (starting at 7.3°/s(2) and increasing at 0.04°/s(2)/s) until 400°/s was reached after 38 s. This stimulus was designed to offset the ~15 s vestibular ocular reflex time constant (and the 150 s adaptation time constant) and produce constant velocity slow phases. In contrast to peripheral lesions, this vestibular stimulation is the result of real head turns and has the push-pull characteristics of natural movements. The procedure was successful, as the average velocity of 31°/s was unchanged over the final 35 s of the acceleration period. In all 10 healthy human subjects, we found a large and stable Alexander's law, with an average velocity-versus-position slope of -0.366 in the first half that was not significantly different in the second half, -0.347. These slopes correspond to integrator time constants of <3 s, are much less than normal time constants (~25 s), and are similar to those observed in patients with peripheral vestibular lesions. Alexander's law also developed, on average, in 10 s. We conclude that Alexander's law is not simply a consequence of non-reciprocal vestibular stimulation.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Ophthalmology Clinic
04 Faculty of Medicine > University Hospital Zurich > Clinic for Neurology
04 Faculty of Medicine > University Hospital Zurich > Clinic for Otorhinolaryngology
04 Faculty of Medicine > Neuroscience Center Zurich
04 Faculty of Medicine > Center for Integrative Human Physiology
Dewey Decimal Classification:570 Life sciences; biology
610 Medicine & health
Language:English
Date:2013
Deposited On:03 Jul 2013 14:54
Last Modified:03 Nov 2017 11:58
Publisher:Springer
ISSN:0014-4819
Publisher DOI:https://doi.org/10.1007/s00221-013-3423-6
PubMed ID:23386125

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