Objectives We aimed to study the role of vestibular input on spatial memory performance in mice that had undergone bilateral surgical labyrinthectomy, semicircular canal (SCC) occlusion and 4G hypergravity exposure.
Methods Twelve to 16 weeks old ICR mice (n=30) were used for the experiment. The experimental group divided into 3 groups. One group had undergone bilateral chemical labyrinthectomy, and the other group had performed SCC occlusion surgery, and the last group was exposed to 4G hypergravity for 2 weeks. The movement of mice was recorded using camera in Y maze which had 3 radial arms (35 cm long, 7 cm high, 10 cm wide). We counted the number of visiting arms and analyzed the information of arm selection using program we developed before and after procedure.
Results The bilateral labyrinthectomy group which semicircular canal and otolithic function was impaired showed low behavioral performance and spacial memory. The semicircular canal occlusion with CO2 laser group which only semicircular canal function was impaired showed no difference in performance activity and spatial memory. However the hypergravity exposure group in which only otolithic function impaired showed spatial memory function was affected but the behavioral performance was spared. The impairment of spatial memory recovered after a few days after exposure in hypergravity group.
Conclusions This spatial memory function was affected by bilateral vestibular loss. Space-related information processing seems to be determined by otolithic organ information rather than semicircular canals. Due to otolithic function impairment, spatial learning was impaired after exposure to gravity changes in animals and this impaired performance was compensated after normal gravity exposure.
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Galvanic Vestibular Stimulation Improves Spatial Cognition After Unilateral Labyrinthectomy in Mice Thanh Tin Nguyen, Gi-Sung Nam, Jin-Ju Kang, Gyu Cheol Han, Ji-Soo Kim, Marianne Dieterich, Sun-Young Oh Frontiers in Neurology.2021;[Epub] CrossRef
The Differential Effects of Acute Right- vs. Left-Sided Vestibular Deafferentation on Spatial Cognition in Unilateral Labyrinthectomized Mice Thanh Tin Nguyen, Gi-Sung Nam, Jin-Ju Kang, Gyu Cheol Han, Ji-Soo Kim, Marianne Dieterich, Sun-Young Oh Frontiers in Neurology.2021;[Epub] CrossRef
Background and Objectives: In this research, movements of mouse after labyrinthectomy were analyzed to determine the degree of vestibular dysfunction and compensation. Materials and Methods: By using an infrared lamp, mouse movements were recorded for 100 seconds in a dark room. The experimental area was manufactured as a circular space with a diameter of 60 cm. The movements of five mice labyrinthectomized on right side were observed and recorded at 3 hours, 9 hours and 120 hours after the operation, and also the ten mice of control group. Results: The differences between the total moving distances and the rotating angle from the origin that set the center of round field between groups were analyzed with pictures of 1 frame per second. It is concluded that all 4 groups show significant differences between its mean rotation angle and total moving distances statistically. At 9 hours after right labyrinthectomy, mice tended to turn clockwise; but at 120 hours, there was no significant difference between clockwise and counter-clockwise rotation. Conclusion: Measuring the movement of mouse in round free field can be the proper method to determine the degree of vestibular dysfunction and vestibular compensation. This test was time-saving and cost-effective method.