Research in Vestibular Science

Original Articles

Effect of Korean Red Ginseng on Early Vestibular Function Restoration after Unilateral Labyrinthectomy: Jiyeon Lee, Mi Joo Kim, Gyu Cheol Han; Res Vestib Sci. 2020;19(3):79-88. Published online September 15, 2020; DOI: https://doi.org/10.21790/rvs.2020.19.3.79

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Abstract PDF: Objectives
Vertigo is a common condition. Definitive treatment is to induce vestibular compensation. Currently, no medications have been discovered that enhance vestibular functional restoration. The current study was conducted to evaluate the ability of ordinary Korean red ginseng (KRG) to induce vestibular compensation.
Methods
Twelve Sprague-Dawley rats were divided into two groups. Five rats (KRG group) were fed KRG extract (100 mg/kg) for 2 weeks before undergoing unilateral labyrinthectomy (ULx). The remaining seven rats (control group) were untreated before ULx. After surgery, all animals were housed in the same environment without being fed additional extract. To evaluate vestibular function, gain of the horizontal nystagmus to 0.2 Hz with a peak velocity of 100°/second sinusoidal rotation was compared and analyzed before ULx as well as 3 and 7 days after surgery.
Results
Before the operation, gain of the control and KRG group were 0.81±0.05 and 0.88±0.08, respectively, with 0.2-Hz stimulation. This value decreased to 0.43±0.08 and 0.53±0.08, respectively on 3 days after operation (p=0.047), and it was 0.40±0.06 and 0.68±0.11, respectively on 7 days after surgery. The difference of gain between the two groups was statistically significant at each 3 and 7 days (p＜0.05). By confirming c-Fos protein expression in medial vestibular nuclei, the functional effect of KRG causing vestibular modulation was confirmed.
Conclusions
Rats treated with KRG showed more rapid and complete recovery after acute vestibular loss compared to untreated animals. Therefore, KRG could be one of candidate for the useful medication of vestibular diseases.

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.

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.

Review

Understanding of Structure and Function of Vestibular Cortex: Min Sun Kim, Jae Hee Lee, Gyoung Wan Lee, Byung Rim Park; Res Vestib Sci. 2010;9(1):1-11.

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Abstract PDF: The vestibular end-organs generate very sophisticated gravity sensory information about head movement by sensing head acceleration in three-dimensional space. Vestibular information is crucial for higher brain functions such as cognition of spatial orientation, spatial memory, and perception of self-motion. The term “vestibular cortex” represents cortical area where vestibular information is processed, converged with other sensory inputs to maintain cortical functions. The vestibular cortex gives rise to commend signals that control the vestibulosomatic reflex through the modulation of vestibular nuclear activity in the brainstem. The vestibular cortex includes such different cortical regions as the premotor region of the frontal cortex, parietal areas, temporal areas, and a central core region called parietoinsular vestibular cortex. This paper summarizes systemically animal and clinical research data concerned with the vestibular cortex in order to understand anatomy and functions of the vestibular cortex and to provide a basic literature for further study.

Original Articles

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.

Effect of Ginkgo biloba on Expression of c-Fos Protein in the Vestibular Nuclear Complex following Unilateral Labyrinthectomy in Rats: Dong Ok Choi, Sun Kyung Kim, Myung Ae Choi, Moon Young Lee, Min Sun Kim, Eun Ho Park, Byung Rim Park; J Korean Bal Soc. 2003;2(2):163-169.

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Abstract PDF: Background
and Objectives: The neuroprotective effect of Ginkgo biloba has been demonstrated in several in vivo and in vitro models. The effect of Ginkgo biloba on vestibular compensation following unilateral labyrinthectomy (UL) was investigated. Material and Methods: Spontaneous nystagmus and c-Fos protein expression were measured following UL in Sprague-Dawley rats with pretreatment of Ginkgo biloba (50 mg/kg, i.p.).
Results
After pretreatment with Ginkgo biloba (50 mg/kg, i.p.) expression of c-Fos protein in the vestibular nuclear complex and frequency of spontaneous nystagmus were measured till 24 hours after UL. UL produced spontaneous nystagmus with frequency of 124±2.2 beats/min at post-op 2 hrs and 70±3.1 beats/min at post-op 24 hrs. Pretreatment with Ginkgo biloba significantly decreased the frequency of spontaneous nystagmus till post-op 24 hrs compared to control group (p<0.05). UL produced marked expression of c-Fos protein in bilateral medial vestibular nucleus, inferior vestibular nucleus, and superior vestibular nucleus, and the number of expression was significantly higher in contralateral vestibular nuclei to the lesion than ipsilateral vestibular nuclei at post-op 2 hrs (p<0.01). The number of c-Fos protein expression was decreased with time and significantly higher in ipsilateral vestibular nuclei than contralateral ones at post-op 24 hrs (p<0.01). Pretreatment with Ginkgo biloba significantly decreased the number of c-Fos protein expression following UL (p<0.01) and abolished the asymmetry of c-Fos protein expression in bilateral vestibular nuclei at post-op 24 hrs.
Conclusion
These results suggest that Ginkgo biloba may facilitate vestibular compensation following UL through modulation of neurotransmitters and neuroprotective effects.

Spatio-temporal Changes on c-Fos Protein Expression in the Brain Stem Nuclei following Arsanilate-induced Unilateral Labyrinthectomy in Rats: Jae Hyo Kim, Chang Ig Choi, Moon Young Lee, Min Sun Kim, Byung Soo Soh, Eun Ho Park, Byung Rim Park; J Korean Bal Soc. 2003;2(1):86-94.

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Abstract PDF: Spatio-temporal changes on c-Fos protein expression were investigated in vestibular compensation following unilateral labyrinthectomy (UL) induced by injection of arsanilate into the middle ear cavity, chemical labyrinthectomy, or surgical labyrinthectomy in medial vestibular nuclei (MVN), prepositus hypoglossal nuclei (PrH), and inferior olivary nuclei (ION) of Sprague-Dawley rats. Number of spontaneous nystagmus in surgical labyrinthectomy group was 28.2±1.2 beats/10 sec at post-op 2 hs and the nystagmus disappeared 76 hs after UL. In chemical labyrinthectomy group, spontaneous nystagmus occurred 6 hs after UL and increased up to maximum at 12 hs and disappeared 96 hs. Head deviation in surgical labyrinthectomy group reached a peak at post-op 2 hs and recovered to control level at 144 hs, but chemical labyrinthectomy produced head deviation 24 hs after UL and increased degree of the deviation over time till 144 hs. Expression of c-Fos protein in surgical labyrinthectomy group at post-op 2 hs was 81±19.4 cells in ipsilateral MVN to the lesion side and 212±60 cells in contralateral MVN, which showed severe asymmetry between bilateral MVN, and decrease of c-Fos protein expression was more in contralateral MVN than in ipsilateral MVN at 6 hs. Chemical labyrinthectomy expressed more c-Fos protein in contralateral MVN 6 hs after UL and in ipsilateral MVN 12 hs after UL, which showed asymmetry of c-Fos protein expression between bilateral MVN. And the expression in ipsilateral MVN of chemical labyrinthectomy group was increased gradually 48 hs after UL and reached a peak at 72 hs. In chemical labyrinthectomy group, expression of c-Fos protein in PrH was increased more in ipsilateral than in contralateral 6 hs after UL and more in contralateral 12 hs after UL, and ION showed more expression of c-Fos protein in contralateral than in ipsilateral 6 hs after UL through 72 hs. These results suggest that the course of vestibular compensation and the temporal expression of c-Fos protein in the brain stem nuclei following UL differed between surgical and chemical labyrinthectomy.

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