Research in Vestibular Science

Original Articles

Role of the Cerebral Cortex on Vestibular Compensation Following Unilateral Labyrinthectomy in Rats: Hyun Kwang Ryoo, Seung Bum Yang, Min Sun Kim, Byung Rim Park; Res Vestib Sci. 2015;14(3):75-82.

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Abstract PDF: Objective: The cerebral cortex can modulate vestibular functions through direct control of neuronal activities in the vestibular nuclei. The purpose of this study was to investigate the effect of unilateral cortical lesion or cortical stimulation on static vestibular symptoms and vestibular nuclear activities at the acute stage of vestibular compensation following unilateral labyrinthectomy (UL) in rats.
Methods
The photothrombic ischemic injury using rose bengal was induced in the primary motor cortex or primary sensory cortex, and electrical stimulation was applied to the primary motor cortex, primary sensory cortex, or sencondary sensory cortex, respectively, in unilateral labyrinthectomized rats. Static vestibular symptoms including ocular movement and postural deficits, and expression of c-Fos protein in the medial vestibular nucleus (MVN) were measured.
Results
Lesion of the motor cortex produced a marked postural deficit with paralytic weakness in the hindlimb contralateral to UL. Number of spontaneous nystagmus in animals receiving cortical lesion was significantly increased 2, 6, and 12 hours after UL compared with animals being UL only. Lesion of the primary motor cortex or stimulation of the S2 sensory cortex decreased expression of c-Fos protein in MVN following UL compared with UL only group. Electrical stimulation of S2 sensory areas caused significant reduction of static vestibular symptoms and decreased expression of c-Fos protein in MVN 24 hours following UL.
Conclusion
The present results suggest that cerebral cortex involves in recovery of static vestibular symptoms during vestibular compensation following UL.

Role of the Peripheral Vestibular End Organ in the Expression of c-Fos Protein in the Medial Vestibular Nucleus Following Occlusion of the Anterior Inferior Cerebellar Artery: Nari Kim, Jae Hee Lee, Myoung Ae Choi, Byung Geon Park, Min Sun Kim, Byung Rim Park; Res Vestib Sci. 2012;11(2):51-58.

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Abstract PDF: Background and Objectives: The present study investigated the role of the peripheral vestibular end organ in vestibular symptoms and temporal changes in expression of c-Fos protein in the vestibular nuclei following anterior inferior cerebellar artery (AICA) occlusion using rats with unilateral or bilateral labyrinthectomy. Materials and Methods: Expression of c-Fos protein in the vestibular nuclei was measured 2, 12, 24, and 48 hours after AICA occlusion. Results: Unilateral AICA occlusion significantly induced expression of c-Fos protein bilaterally in the medial, inferior, superior, and lateral vestibular nuclei. Following AICA occlusion, the medial vestibular nucleus (MVN) showed the highest expression of c-Fos protein among the 4 vestibular nuclei. The expression of c-Fos protein was asymmetric between the bilateral MVN, showing higher expression in the MVN contralateral to the side of AICA occlusion compared to the ipsilateral MVN. The degree of asymmetry in c-Fos protein expression between the bilateral MVN peaked 12 hours after AICA occlusion. The expression of c-Fos protein gradually decreased 24 hours after AICA occlusion and returned to control levels 48 hours after AICA occlusion. Unilateral labyrinthectomy significantly decreased expression of c-Fos protein in the MVN ipsilateral to the side of labyrinthectomy following AICA occlusion. Moreover, bilateral labyrinthectomy significantly decreased expression of c-Fos protein in the bilateral MVN flowing AICA occlusion. Conclusion: These results suggest that afferent signals from the peripheral vestibular end organ are crucial to the expression of c-Fos protein in the MVN following AICA occlusion and that expression of c-Fos protein is sustained for 24 hours after AICA occlusion.

Quantification of Vestibulospinal Reflex Under the Stress Condition on Both Soleus Muscles: Mi Joo Kim, Seo Jin Jang, Eun Ji Lee, Ah Ram Yu, Jong Hyun Hwang, Gyu Cheol Han, Ju Kang Lee; Res Vestib Sci. 2012;11(1):14-22.

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Abstract PDF: Therefore, by establishing method that enables to track and observe quantified VSR, the reliability of experiment is attempted to be increased. Materials and Methods:On five SD Rats to measure electromyogram (EMG), electrodes, in the form of stranded cables composed of seven wires, are chronically implanted on both sides of the soleus muscles. Pre and post operative condition of sitting still, standing, and ladder step walking was compared before, and six and twenty four hours after a unilateral labyrinthectomy with quantified muscle activity in maximal voluntary activity. Simultaneously by using multi modality electric potential plus package, the muscle activity between the two legs was tracked and compared. Results: In the sitting still position, the left/right soleus muscle activities were 25.7/26.0 μV before a unilateral labyrinthectomy which was changed after the surgery with the value of 23.1/8.1 μV and 23.4/14.3 μV when six and twenty four hours passed respectively. In the standing position, 92.8/124.0 μV of preoperative value was changed to 89.6/37.3 μV six hours after the unilateral labyrinthectomy, and it was 97.0/54.7 μV 24 hours after. The preoperative value in ladder step walking test was 56.2/86.0 μV, and postoperative ones were 54.9/21.2 μV and 55.7/38.0 μV after six and twenty four hours respectively. Conclusion: VSR assessment method by using quantitative EMG well reflects the process of vestibular compensation, and to maintain the tension of extensor muscles, ladder step walking test is shown to be useful.

Measuring the Behavioral Parameters of Mouse Following Unilateral Labyrinthectomy in Round Free Field Using an Infrared Lamp and a Simple Webcam Camera: Mi Joo Kim, Hyun Jung Hwang, Seung Won Chung, Gyu Cheol Han; Res Vestib Sci. 2011;10(1):12-18.

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Abstract PDF: 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.

Changes in the Gastrointestinal Motility following Unilateral Labyrinthectomy: Jae Hee Lee, Gyoung Wan Lee, Suck Jun Choi, Eun Ho Park; Res Vestib Sci. 2009;8(1):15-22.

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Abstract PDF: Background and Objectives The temporal changes and the role of glutamate receptors in the recovery of vestibulogastrointestinal symptoms following unilateral labyrinthectomy (UL) were investigated in this study. Vestibulogastrointestinal symptoms were evaluated in terms of gastric emptying and intestinal transit. Materials and Methods Expression of the c-Fos protein was observed in the solitary tract nucleus (STN) and rostral ventrolateral medullary nucleus (RVLM). These were measured at 0.5, 2, 6 and 24 h following UL in rats. Results Gastric emptying and intestinal transit were significantly decreased for 6 h post UL and recovered to control levels within 24 h. Pretreatment of UL animals with MK-801 significantly increased the gastric emptying and intestinal transit. Bilateral labyrinthectomy significantly decreased the gastric emptying and intestinal transit compared to the intact labyrinthine animals but significantly increased when compared to UL animals. The expression of c-Fos protein was significantly increased in STN and RVLM compared to the control animals for 6 h post UL and recovered to control levels within 24 h. The expression was significantly decreased in animals that were pretreated with MK-801. Conclusion These results suggest that UL decreases the gastrointestinal motility, which recovers to control levels within 24 h post UL. Glutamate plays an important role in the recovery of vestibulogastrointestinal symptoms following UL. Key Words: Gastric emptying; c-Fos protein; Glutamate; Gastrointestinal Motility; Unilateral labyrinthectomy

Immunohistochemical Identification of Phosphorylated Extracellular Signal-Regulated Kinase1/2 in Rat Vestibular Nuclei by Unilateral Labyrinthectomy: Myoung Ae Choi, Dong Ok Choi, Kwang Yong Kim, Moon Young Lee, Byung Rim Park, Min Sun Kim; J Korean Bal Soc. 2003;2(2):170-174.

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Abstract PDF: This study evaluated the expression of phosphorylated signal-regulated kinase1/2 (pERK1/2), which is one of the main factors regulating transcription of the cfos oncogene in neurons, in the vestibular nuclei of Sprague-Dawley rats following unilateral labyrinthectomy (UL). Surgical UL was performed to eliminate afferent signals from the peripheral vestibular receptors in the inner ear, under a surgical microscope, 2 hours after anesthesia. Significant numbers of pERK1/2 immunoreactive neurons were seen in the superior, medial, and inferior vestibular nuclei. There were more pERK1/2 immunoreactive cells in the vestibular nuclei contralateral than in the vestibular nuclei ipsilateral to the injured labyrinth, which resulted in significant asymmetric expression of pERK1/2 immunoreactive cells. Subsequently, the pERK1/2 immunoreactivity decreased rapidly, disappearing 90 min after labyrinthectomy. No pERK1/2 labeling was seen in the lateral vestibular nucleus. These results suggest that intracellular signal pathways for the activation of extracellular signal-regulated kinase in the vestibular nuclei are involved in lesion-neural plasticity in the vestibular system.

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