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- Magnusson, M
(författare)
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Effect of alertness on the vestibulo-ocular reflex and on the slow rise in optokinetic nystagmus in rabbits
- 1986
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Ingår i: American Journal of Otolaryngology - Head and Neck Medicine and Surgery. - 0196-0709. ; 7:5, s. 9-353
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Tidskriftsartikel (refereegranskat)abstract
- The effect of alertness on the time constant of the vestibulo-ocular reflex (VOR) and the time constant of the slow rise of the optokinetic nystagmus (OKN) was studied in nine pigmented rabbits. When the rabbits were alerted by vibration, the time constant of the VOR was prolonged, and that of the slow rise in OKN was shortened, whereas the gain of VOR and OKN remained largely unaffected. These findings agree with the suggestion that the state of alertness affects the vestibular system by way of the so-called velocity storage mechanism.
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2. |
- Magnusson, M, et al.
(författare)
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The relationship of optokinetic nystagmus to pursuit eye movements, vestibular nystagmus and to saccades in humans. A clinical study
- 1986
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Ingår i: Acta Oto-Laryngologica. - 0001-6489. ; 101:5-6, s. 70-361
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Tidskriftsartikel (refereegranskat)abstract
- The relationship of mean velocity of optokinetic nystagmus (OKN) to pursuit eye movements (PEM), to vestibular nystagmus and to voluntary saccades was analysed in 10 patients with peripheral vestibular lesions and in 30 patients with central vestibular lesions. PEM and vestibular nystagmus were significantly correlated to OKN, suggesting that a common neural pathway is used in the generation of these eye movements. Weak or no correlation was found between saccadic peak velocity and slow phase velocity of OKN. Using multiple linear regression analysis, it was found that 78.5% of the variation in the slow-phase velocity of OKN could be explained by a synthesis of PEM and vestibular test data. PEM test data were more powerful than those of vestibular nystagmus in deduction of OKN. The possible appearance of slow build-up of OKN could not be deduced from the reduction of PEM. Hence, the relationship between PEM and OKN in man is not a simple linear one, but is more complex.
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3. |
- Magnusson, M, et al.
(författare)
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Velocity and asymmetry of optokinetic nystagmus in the evaluation of vestibular lesions
- 1986
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Ingår i: Acta Oto-Laryngologica. - 0001-6489. ; 102:1-2, s. 65-74
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Tidskriftsartikel (refereegranskat)abstract
- Optokinetic nystagmus (OKN) at a constant stimulus velocity of 90 degrees/s was studied in 50 healthy subjects and three different groups of patients: 10 with vestibular neuritis (VN), 17 with unilateral infratentorial lesion (UI) and 13 patients with bilateral infratentorial lesion (BI). Among healthy subjects, OKN decreased with age in those over 42 and 44 years for maximum and mean velocity, respectively. The maximum velocity of OKN discriminated between the healthy subjects and the groups of patients rather better than did mean velocity of OKN. Asymmetry of either mean or maximum velocity contributed only marginally to correct group assignment. By subjecting test data on velocity and asymmetry variables to linear discriminant function analysis, 80% of subjects could be correctly classified as healthy/not healthy, and 64% assigned to the correct group according to diagnosis. Analysis of OKN data satisfactorily discriminated BI and UI patients from VN patients and healthy subjects, and is thus useful in assessing infratentorial vestibular lesions.
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