• The Journal of Korean Physical Therapy
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• v.2 no.1
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• pp.75-83
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• 1990

The purpose of this study was to determine if any differences exist in eye contact before and after vestibulaar stimulation in mentally retarded children. The subjects of this study were 20 mentally retarded children with a mean age of 9 years and 8 months and a mean intelligence quotient of $30.4{\pm}9.1$. Vestibular stimulation was given for 15 minutes, 5 times a week, for 4 weeks from September 1 to September 30, 1989. Equipment used included a rocking-horse, see-saw and scooter board. Two testers used a digital watch calibrated to 1/100 second to measure object-eye contact duration and the Blocks and Shapes test for determining frequency of object-eye contact in the subjects. The results of this study were as follows : 1. There was a significant prolongation in the duration of eye contact after 15 minutes of vestibular stimulation (p<0.005). 2. There was no significant difference in duration of eye-object contact between the first and last vestibular stimulation. 3. There was no significant difference in the length of time of attention paid to objects (frequency of eye-object contact) before and after 15 minutes of vestibular stimulation on the first vestibular stimulation. 4. There was no significant difference in the frequency of eye-object contact between the first and first vestibular stimulation. In conclusion, there was u significant improvement in duration of eye-object contact on intrasession measurement in mentally retarded children. However, there was no significant improvement over time after 4 weeks of vestibular stimulation on intersession measurement. Nor was there any statistically significant improvement in frequency of eye-object contact over time during the study period.

• Journal of Audiology & Otology
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• v.25 no.3
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• pp.152-158
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• 2021

Background and Objectives: Balance control is maintained in stationary and dynamic conditions, with coordinated muscle responses generated by somatosensory, vestibular, and visual inputs. This study aimed to investigate how the vestibular system is affected in the presence of an optical illusion to better understand the interconnected pathways of the visual and vestibular systems. Subjects and Methods: The study involved 54 young adults (27 males and 27 females) aged 18-25 years. The recruited participants were subjected to the cervical vestibular evoked myogenic potentials (cVEMP) test and video head impulse test (vHIT). The cVEMP and vHIT tests were performed once each in the absence and presence of an optical illusion. In addition, after each test, whether the individuals felt balanced was determined using a questionnaire. Results: cVEMP results in the presence of the optical illusion showed shortened latencies and increased amplitudes for the left side in comparison to the results in the absence of the optical illusion (p≤0.05). When vHIT results were compared, it was seen that the right lateral and bilateral anterior canal gains were increased, almost to 1.0 (p<0.05). Conclusions: It is thought that when the visual-vestibular inputs are incompatible with each other, the sensory reweighting mechanism is activated, and this mechanism strengthens the more reliable (vestibular) inputs, while suppressing the less reliable (visual) inputs. As long as the incompatible condition persists, the sensory reweighting mechanism will continue to operate, thanks to the feedback loop from the efferent vestibular system.

• Korean Journal of Audiology
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• v.25 no.3
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• pp.152-158
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• 2021

Background and Objectives: Balance control is maintained in stationary and dynamic conditions, with coordinated muscle responses generated by somatosensory, vestibular, and visual inputs. This study aimed to investigate how the vestibular system is affected in the presence of an optical illusion to better understand the interconnected pathways of the visual and vestibular systems. Subjects and Methods: The study involved 54 young adults (27 males and 27 females) aged 18-25 years. The recruited participants were subjected to the cervical vestibular evoked myogenic potentials (cVEMP) test and video head impulse test (vHIT). The cVEMP and vHIT tests were performed once each in the absence and presence of an optical illusion. In addition, after each test, whether the individuals felt balanced was determined using a questionnaire. Results: cVEMP results in the presence of the optical illusion showed shortened latencies and increased amplitudes for the left side in comparison to the results in the absence of the optical illusion (p≤0.05). When vHIT results were compared, it was seen that the right lateral and bilateral anterior canal gains were increased, almost to 1.0 (p<0.05). Conclusions: It is thought that when the visual-vestibular inputs are incompatible with each other, the sensory reweighting mechanism is activated, and this mechanism strengthens the more reliable (vestibular) inputs, while suppressing the less reliable (visual) inputs. As long as the incompatible condition persists, the sensory reweighting mechanism will continue to operate, thanks to the feedback loop from the efferent vestibular system.

• Biomedical Science Letters
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• v.16 no.1
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• pp.46-52
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• 2010

This study was designed to investigate the effects of sphingosine-1-phosphate on the neuronal activity of rat medial vestibular nuclear neurons. Sprague-Dawley rats aged 14 to 16 days were decapitated under ether anesthesia. After treatment with pronase and thermolysin, the dissociated medial vestibular nuclear neurons were transferred into a chamber on an inverted microscope. Spontaneous action potentials and potassium currents were recorded by standard patch-clamp techniques under current and voltage-clamp modes respectively. 15 medial vestibular nuclear neurons revealed excitatory responses to 1 and $5\;{\mu}M$ of sphingosine-1-phosphate. The spike frequency and resting membrane potential of these cells were increased by sphingosine-1-phosphate. The amplitude of afterhyperpolarization was decreased by sphingosine-1-phosphate. Whole potassium currents of medial vestibular nuclear neurons were decreased by sphingosine-1-phosphate (n=12). Sphingosine-1-phosphate did not affect the charybdotoxin-treated potassium currents. These experimental results suggest that sphingosine-1-phosphate increases the neuronal activity of the medial vestibular nuclear neurons by altering the resting membrane potential and afterhyperpolarization.

• The Korean Journal of Physiology and Pharmacology
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• v.6 no.4
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• pp.193-197
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• 2002

In spite of abundant anatomical evidences for the fiber connection between vestibular nuclei and inferior olivary (IO) complex, the transmission of vestibular information through the vestibulo- olivo-cerebellar climbing fiber pathway has not been physiologically established. The aims of the present study were to investigate whether there are IO neurons specifically responding to horizontal rotation and also in which subregions of IO complex these vestibularly-activated neurons are located. The extracellular recording was made in 68 IO neurons and responses of 46 vestibularly-activated cells were analyzed. Most of the vestibularly-activated IO neurons responded to signals of vertical rotation (roll), while a small number (13/46) of recorded cells were activated by horizontal canal signal (yaw). Regardless of yaw-sensitive or roll-sensitive, vestibular IO neurons were excited, when the animal was rotated to the side contralateral to the recording side. The gain and excitation phase were very similar to otolithic or vertical-canal responses. Histologic identification of recording sites showed that most of vestibular IO neurons were located in ${\beta}$ subnucleus. Electrical stimulation of a HSC evoked an inhibitory effect on the excitability of the ipsilateral IO neurons. These results suggest that IO neurons mainly in the ${\beta}$ subnucleus receive vestibular signals from semicircular canals and otolithic organs, encode them, and transmit vestibular information to the cerebellum.

• The Korean Journal of Physiology and Pharmacology
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• v.6 no.6
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• pp.287-291
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• 2002

Intrinsic excitabilities of acutely isolated medial vestibular nucleus (MVN) neurons of rats with normal labyrinth and with undergoing vestibular compensation from 30 min to 24 h after unilateral vestibular deafferentation (UVD) were compared. In control rats, proportions of type A and B cells were 30 and 70%, respectively, however, the proportion of type A cells increased following UVD. Bursting discharge and irregular firing patterns were recorded from 2 to 12 h post UVD. The spontaneous discharge rate of neurons in the ipsilesional MVN increased significantly at 2 h post-UVD and remained high until 12 h post-UVD in both type A and type B cells. After-hyperpolarization (AHP) of the MVN neurons decreased significantly from 2 h post-UVD in both types of cells. These results suggest that the early stage of vestibular compensation after peripheral neurectomy is associated with an increase in intrinsic excitability due to reduction of AHP in MVN neurons.

• Journal of International Academy of Physical Therapy Research
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• v.5 no.1
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• pp.668-674
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• 2014

The purpose of this study was to analysis of the effect of proprioceptor training and vestibular organ training for balance ability. The subjects was consist of two different subjects group, proprioceptor training group and vestibular organ training group. Proprioceptor training group consisted of 10 subjects and vestibular organ training group consisted of 10 subjects. Training was performed 3 times per week, 30 minutes per day, for 3 weeks. Balance ability analysis was performed using Romberg's one leg standing test and BT4 when opened eyes and closed eyes. The analysis results were as follows. There was no significant differences in balance after the training in both groups when they opened their eyes(p<.05). But there was significant differences in balance after the training in both groups when they closed their eyes(p<.05). And there was no significant difference in balance after the training between the proprioceptor training group and the vestibular organ training group when they closed their eyes(p<.05). Given the above results, proprioceptor training and vestibular organ training enhanced balance but there was no significant difference between the two methods.

• The Korean Journal of Physiology and Pharmacology
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• v.22 no.4
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• pp.363-368
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• 2018

Hypotension is one of the potential causes of dizziness. In this review, we summarize the studies published in recent years about the electrophysiological and pharmacological mechanisms of hypotension-induced dizziness and the role of the vestibular system in the control of blood pressure in response to hypotension. It is postulated that ischemic excitation of the peripheral vestibular hair cells as a result of a reduction in blood flow to the inner ear following hypotension leads to excitation of the central vestibular nuclei, which in turn may produce dizziness after hypotension. In addition, excitation of the vestibular nuclei following hypotension elicits the vestibulosympathetic reflex, and the reflex then regulates blood pressure by a dualcontrol (neurogenic and humoral control) mechanism. In fact, recent studies have shown that peripheral vestibular receptors play a role in the control of blood pressure through neural reflex pathways. This review illustrates the dual-control mechanism of peripheral vestibular receptors in the regulation of blood pressure following hypotension.

• Journal of Audiology & Otology
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• v.25 no.2
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• pp.89-97
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• 2021

Background and Objectives: Bilateral sequential vestibular neuritis (BSVN) is a rare condition in which an inflammation or an ischemic damage of the vestibular nerve occurs bilaterally in a sequential pattern. We described four cases of BSVN. Subjects and Methods: Every patient underwent video-head impulse test during the first and the second episode of vestibular neuritis (VN), furthermore they have been studied with radiological imaging. Results: Contralateral VN occurred after a variable period from prior event. Vestibular function recovered from the first episode in one case. The other three patients developed contralateral VN. One case was due to a bilateral VN in association with a Ramsay-Hunt syndrome, in another patient clinical records strongly suggested an ischemic etiology, whereas in two cases aetiology remained uncertain. Two patients subsequently developed a benign paroxysmal positional vertigo involving the posterior canal on the side of the latest VN (Lindsay-Hemenway syndrome). Conclusions: Instrumental vestibular assessment represents a pivotal tool to confirm the diagnosis of VN and BSVN.

• Korean Journal of Audiology
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• v.25 no.2
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• pp.89-97
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• 2021

Background and Objectives: Bilateral sequential vestibular neuritis (BSVN) is a rare condition in which an inflammation or an ischemic damage of the vestibular nerve occurs bilaterally in a sequential pattern. We described four cases of BSVN. Subjects and Methods: Every patient underwent video-head impulse test during the first and the second episode of vestibular neuritis (VN), furthermore they have been studied with radiological imaging. Results: Contralateral VN occurred after a variable period from prior event. Vestibular function recovered from the first episode in one case. The other three patients developed contralateral VN. One case was due to a bilateral VN in association with a Ramsay-Hunt syndrome, in another patient clinical records strongly suggested an ischemic etiology, whereas in two cases aetiology remained uncertain. Two patients subsequently developed a benign paroxysmal positional vertigo involving the posterior canal on the side of the latest VN (Lindsay-Hemenway syndrome). Conclusions: Instrumental vestibular assessment represents a pivotal tool to confirm the diagnosis of VN and BSVN.