TY - JOUR
T1 - Dynamics of the horizontal vestibuloocular reflex after unilateral labyrinthectomy
T2 - Response to high frequency, high acceleration, and high velocity rotations
AU - Sadeghi, Soroush G.
AU - Minor, Lloyd B
AU - Cullen, Kathleen E.
N1 - Funding Information:
Acknowledgements In this study, David Lasker implemented the mathematical model described in the Appendix that accompanies this paper electronically. This model had been previously developed by him for the squirrel monkey horizontal VOR (Lasker et al. 1999; Minor et al. 1999). He optimized the parameters used in this model from the data for the macaque VOR and prepared the figures for the simulated responses. We thank Dr. Charles Della Santina, Mathieu Beraneck, Marion Van Horn, and Ariana Andrei for critically reading the manuscript. This work was supported by the Canadian Institutes of Health Research (CIHR) and NIH R01 DC02390.
PY - 2006/11
Y1 - 2006/11
N2 - Loss of vestibular information from one labyrinth results in a marked asymmetry in the horizontal vestibuloocular reflex (VOR). The results of prior studies suggest that long-term deficits in VOR are more severe in response to rapid impulses than to sinusoidal head movements. The goal of the present study was to investigate the VOR following unilateral labyrinthectomy in response to different stimuli covering the full range of physiologically relevant head movements in macaque monkeys. The VOR was studied 1-39 days post-lesion using transient head perturbations (up to 12,000°/s2), rapid rotations (up to 500°/s), and sinusoidal rotations (up to 15 Hz). In response to rotations with high acceleration or velocity, both contra- and ipsilesional gains remained subnormal. VOR gains decreased as a function of increasing stimulus acceleration or velocity, reaching minimal values of 0.7-0.8 and 0.3-0.4 for contra and ipsilesional rotations, respectively. For sinusoidal rotations with low frequencies and velocities, responses to contralesional stimulation recovered within ∼ 4 days. With increasing velocities and frequencies of rotation, however, the gains of contra- and ipsilesional responses remained subnormal. For each of the most challenging stimuli tested (i.e., 12,000°/s2 transient head perturbations, 500°/s fast whole-body rotations and 15 Hz stimulation) no significant compensation was observed in contra- or ipsilesional responses over time. Moreover, we found that gain of the cervico-ocular reflex (COR) remained negligible following unilateral loss indicating that neck reflexes did not contribute to the observed compensation. VOR responses elicited by both sinusoidal and transient rotations following unilateral labyrinthectomy could be described by the same mathematical model. We conclude that the compensated VOR has comparable response dynamics for impulses and sinusoidal head movements.
AB - Loss of vestibular information from one labyrinth results in a marked asymmetry in the horizontal vestibuloocular reflex (VOR). The results of prior studies suggest that long-term deficits in VOR are more severe in response to rapid impulses than to sinusoidal head movements. The goal of the present study was to investigate the VOR following unilateral labyrinthectomy in response to different stimuli covering the full range of physiologically relevant head movements in macaque monkeys. The VOR was studied 1-39 days post-lesion using transient head perturbations (up to 12,000°/s2), rapid rotations (up to 500°/s), and sinusoidal rotations (up to 15 Hz). In response to rotations with high acceleration or velocity, both contra- and ipsilesional gains remained subnormal. VOR gains decreased as a function of increasing stimulus acceleration or velocity, reaching minimal values of 0.7-0.8 and 0.3-0.4 for contra and ipsilesional rotations, respectively. For sinusoidal rotations with low frequencies and velocities, responses to contralesional stimulation recovered within ∼ 4 days. With increasing velocities and frequencies of rotation, however, the gains of contra- and ipsilesional responses remained subnormal. For each of the most challenging stimuli tested (i.e., 12,000°/s2 transient head perturbations, 500°/s fast whole-body rotations and 15 Hz stimulation) no significant compensation was observed in contra- or ipsilesional responses over time. Moreover, we found that gain of the cervico-ocular reflex (COR) remained negligible following unilateral loss indicating that neck reflexes did not contribute to the observed compensation. VOR responses elicited by both sinusoidal and transient rotations following unilateral labyrinthectomy could be described by the same mathematical model. We conclude that the compensated VOR has comparable response dynamics for impulses and sinusoidal head movements.
KW - High acceleration
KW - High frequency
KW - High velocity
KW - Unilateral labyrinthectomy
KW - VOR
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U2 - 10.1007/s00221-006-0567-7
DO - 10.1007/s00221-006-0567-7
M3 - Article
C2 - 16957885
AN - SCOPUS:33750341909
SN - 0014-4819
VL - 175
SP - 471
EP - 484
JO - Experimental Brain Research
JF - Experimental Brain Research
IS - 3
ER -