Development of Eye Position Dependency of Slow Phase Velocity during Caloric Stimulation

Bockisch, Christopher J.; Khojasteh, Elham; Straumann, Dominik; Hegemann, Stefan

doi:10.1371/journal.pone.0051409

Cited by 10 publications

(9 citation statements)

References 27 publications

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“…However, the Doslak model also predicts that the velocity-versus-position slope should be independent of nystagmus speed (above a threshold), but that is not the case in our study (Fig. 4c), nor with caloric stimulation (Bockisch et al 2012). The model of Doslak et al also predicts Alexander's law should occur with the normal VOR, yet it is not found with 0.5-Hz sinusoidal head rotations on a turntable (Robinson et al 1984) or head impulses (Anagnostou et al 2011;Anastasopoulos and Anagnostou 2012).…”

Section: Discussioncontrasting

confidence: 76%

“…With normal, reciprocal stimulation of the canals, the gain changes with eye position cancel, producing a VOR that does not depend on eye position. Thus, this model does not predict Alexander's law during constant acceleration protocols, as we observed here, nor with bilateral bithermal caloric stimulation (Bockisch et al 2012). Constant acceleration and caloric stimulation protocols that show Alexander's law produce very low-frequency stimulation, whereas the VOR studies that do not show Alexander's law use higher-frequency stimuli.…”

Section: Discussioncontrasting

confidence: 74%

“…In our experiment, Alexander's law was found on average 10 s after the onset of stimulation. Third, in our recent study with caloric stimulation, we observed Alexander's law with bilateral bithermal stimulation (cold on one side, warm on the other) (Bockisch et al 2012). This stimulus preserves the push-pull pattern of natural stimulation and is further evidence against the Robinson et al's (1984) hypothesis.…”

Section: Discussionsupporting

confidence: 62%

“…We recently observed Alexander's law with bilateral bithermal stimulation (cold on one side, warm on the other) (Bockisch et al 2012), which preserves the normal pushpull pattern of stimulation from real head movements, which suggests Robinson et al's (1984) hypothesis should be re-evaluated. Peripheral vestibular disorders and caloric stimulation contain frequencies that are much lower than those produced by natural head movements and could help explain why Alexander's law has not been observed with higher-frequency head rotations (Robinson et al 1984;Anagnostou et al 2011).…”

Section: Introductionmentioning

confidence: 74%

“…Spontaneous nystagmus in patients with vestibular lesions often has a dependency on eye position, first described in 1912 (Alexander 1912) and called Alexander's law, where the slow-phase velocity is highest with gaze in the fast-phase direction. Modern measurements have further quantified Alexander's law in patients (Hegemann et al 2007;Bockisch and Hegemann 2008), and caloric stimulation has been used to simulate peripheral vestibular disorders in healthy subjects and evoke similar patterns of eye position dependency as have been described in patients (Doslak et al 1982;Robinson et al 1984;Jeffcoat et al 2008;Bockisch et al 2012). Hess (1982), and shortly thereafter Robinson et al (1984), proposed that Alexander's law arose from changes in the brainstem/cerebellar velocity-to-position neural integrator, such that the integrator produces a smaller-than-normal command to compensate for elastic forces produced by 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.…”

Section: Introductionmentioning

confidence: 98%

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Eye position dependency of nystagmus during constant vestibular stimulation

et al. 2013

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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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Section: Discussioncontrasting

confidence: 76%

Section: Discussioncontrasting

confidence: 74%

Section: Discussionsupporting

confidence: 62%

Section: Introductionmentioning

confidence: 74%

Section: Introductionmentioning

confidence: 98%

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Eye position dependency of nystagmus during constant vestibular stimulation

et al. 2013

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Numerical modeling and verification by nystagmus slow-phase velocity of the function of semicircular canals

Xiang

Shen

Liu

et al. 2020

Biomech Model Mechanobiol

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Direct perturbation of neural integrator by bilateral galvanic vestibular stimulation

Hong

Shim

Goh

et al. 2016

Med Biol Eng Comput

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Caloric vestibular stimulation (CVS) and galvanic vestibular stimulation (GVS) act primarily on the peripheral vestibular system. Although the electrical current applied during GVS is thought to flow through peripheral vestibular organs, some current may spread into areas within the central nervous system, particularly when the bilateral galvanic vestibular stimulation (bGVS) method is used. According to Alexander's law, the magnitude of nystagmus increases with eccentric gaze movement, due to the function of the neural integrator (NI); thus, if the information for vestibular stimulation corresponds to Alexander's law, the peripheral vestibular organ is stimulated. Therefore, it would appear that if CVS results comply with Alexander's law, and bGVS results do not, the sites stimulated by bGVS are not perfectly located in the peripheral vestibular area. In our experiments on normal human subjects, the magnitude of nystagmus under CVS increased with rising gaze eccentricity in the direction that the magnitude of the nystagmus increases, and this change was found to follow Alexander's law. However, in the case of nystagmus under bGVS, results did not follow Alexander's law. In addition, study of the influences of bGVS at different current intensities on nystagmus magnitude showed that bGVS at 5 mA distorted nystagmus magnitude more than at 3 mA, which suggests bGVS acts not only on the peripheral vestibular nerves, but also on some areas of the central nervous system, particularly the NI. According to our experiments, bGVS directly affects neural integrator function.

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Development of Eye Position Dependency of Slow Phase Velocity during Caloric Stimulation

Cited by 10 publications

References 27 publications

Eye position dependency of nystagmus during constant vestibular stimulation

Eye position dependency of nystagmus during constant vestibular stimulation

Numerical modeling and verification by nystagmus slow-phase velocity of the function of semicircular canals

Direct perturbation of neural integrator by bilateral galvanic vestibular stimulation

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