• The Journal of Korean Physical Therapy
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• v.23 no.6
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• pp.49-53
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• 2011

Purpose: The purpose of this study is to investigate whether dual-hemisphere transcranial direct current stimulation (tDCS) could induce more cortical activity, compared to single-hemisphere, using functional MRI (fMRI). Methods: One right-handed healthy subject was recruited. Three phases of dual-hemisphere tDCS (i.e. anodal tDCS over the left-dominant primary sensoriomotor cortex (SM1) and cathodal tDCS over the right-non dominant SM(1) were consecutively delivered on to a subject, during fMRI scanning. The voxel count and the intensity index in the averaged cortical map were analyzed among the three tDCS phases. Results: Our result showed that cortical activation was observed on all the three phases of the dual-hemisphere tDCS. Voxel count and intensity index were as following; 912 and 4.07 in the first phase, 1102 and 3.90 in the second phase, 1031 and 3.80 in the third phase. Conclusion: This study demonstrated that application of the dual-hemisphere tDCS could induce cortical activity and maintain to recruit cortical neurons. Our findings suggested that application of dual-hemisphere tDCS could produce efficiency of the ongoing tDCS effect to facilitate cortical excitability.

• The Journal of Korean Physical Therapy
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• v.23 no.1
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• pp.77-82
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• 2011

Purpose: Recently, many studies have demonstrated that application of external stimulation can modulate cortical excitability of the human brain. We attempted to observe cortical excitability using functional magnetic resonance imaging (fMRI) during the application of transcranial direct current stimulation (tDCS) or functional electrical stimulation (FES). Methods: We recruited two healthy subjects without a history of neurological or psychiatric problems. fMRI scanning was done during? each constant anodal tDCS and FES session, and each session was repeated three times. The tDCS session consisted of three successive phases (resting phase: 60sec dummy cycle: 10sec tDCS phase: 60sec). The FES session involved stimulation of wrist extensor muscles over two successive phase (resting phase: 15sec FES phase: 15sec). Results: The average map of the tDCS and FES analyses showed that the primary sensory-motor cortex area was activated in all subjects. Conclusion: Our findings show that cortical activation can be induced by constant anodal tDCS and FES. They suggest that the above stimuli have the potential for facilitating brain plasticity and modulating neural excitability if applied as specific therapeutic interventions for brain injured patients.

• The Journal of Korean Physical Therapy
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• v.21 no.4
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• pp.73-79
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• 2009

Purpose: Recently, neurostimulation studies involving manipulation of cortical excitability of the human brain have been increasingly attempted. We investigated whether transcranial direct current stimulation (tDCS) applied to the underlying cerebral cortex, directly induces cortical activation during fMRI scanning. Methods: We recently recruited five healthy subjects without a neurological or psychiatric history and who were right-handed, as verified by the modified Edinburg Handedness Inventory. fMRI was done while constant anodal tDCS was delivered to the underlying SM1 area?? immediately after the pre-stimulation for eighteen minutes. Results: Group analysis yielded an averaged map that showed that the SM1 area and the superior parietal cortex in the ipsilateral hemisphere were activated. The voxel size and peak intensity were, respectively, 82 and 5.22 in the SM1, and 85 and 5.77 in the superior parietal cortex. Conclusion: Cortical activation can be induced by constant anodal tDCS of the underlying motor cortex. This suggests that tDCS may be an effective therapeutic device for enhancing? physical motor function by modulating neural excitability of the motor cortex.

• Sleep Medicine and Psychophysiology
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• v.28 no.2
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• pp.53-69
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• 2021

Sleep disorders, increasingly prevalent in the general population, induce impairment in daytime functioning and other clinical problems. As changes in cortical excitability have been reported as potential pathophysiological mechanisms underlying sleep disorders, multiple studies have explored clinical effects of modulating cortical excitability through non-invasive brain stimulation in treating sleep disorders. In this study, we critically reviewed clinical studies using non-invasive brain stimulation, particularly transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), for treatment of sleep disorders. Previous studies have reported inconsistent therapeutic effects of TMS and tDCS for various kinds of sleep disorders. Specifically, low-frequency repetitive TMS (rTMS) and cathodal tDCS, both of which exert an inhibitory effect on cortical excitability, have shown inconsistent therapeutic effects for insomnia. On the other hand, high-frequency rTMS and anodal tDCS, both of which facilitate cortical excitability, have improved the symptoms of hypersomnia. In studies of restless legs syndrome, high-frequency rTMS and anodal tDCS induced inconsistent therapeutic effects. Single TMS and rTMS have shown differential therapeutic effects for obstructive sleep apnea. These inconsistent findings indicate that the distinctive characteristics of each non-invasive brain stimulation method and specific pathophysiological mechanisms underlying particular sleep disorders should be considered in an integrated manner for treatment of various sleep disorders. Future studies are needed to provide optimized TMS and tDCS protocols for each sleep disorder, considering distinctive effects of non-invasive brain stimulation and pathophysiology of each sleep disorder.

• Korean Journal of Psychosomatic Medicine
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• v.18 no.1
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• pp.3-10
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• 2010

Gilles de la Tourette syndrome is a chronic motor and vocal tic disorder of childhood onset. Abnornmalities in basal ganglia-thalamo-cortical circuits may play an important role in the pathophysiology underlying the involuntary tics. It is often complicated by comorbid attention-deficit/hyperactivity disorder or obsessive-compulsive disorder. Transcranial magnetic stimulation(TMS) is a neurophysiologic technique with research ap-plication. As there is good evidence that this technique can modify cortical activity, repetitive TMS is also used for treatment to change the cortical excitability and therefore affect underlying interconnected cortical-sub-cortical loop. We reviewed the neurophysiologic parameters and the clinical applicability of TMS and rTMS.

• The Journal of Korean Physical Therapy
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• v.21 no.4
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• pp.65-71
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• 2009

Purpose: Transcranial direct current stimulation (tDCS) is a useful method for modulating the brain activity. This study compared the effect of continuous and interrupted tDCS using the change in the movement related cortical potential. Methods: Thirty healthy participants (male: 18 and female: 12) were assigned randomly to three groups; sham tDCS, continuous tDCS, which the current continuously flowed for 10 minutes, and interrupted tDCS, which the interrupted current flowed for 10 minutes (repetition: 4sec stimulation and 5sec rest) at an intensity of 1mA with anodal polarity. The effect of tDCS on the right primary motor area was measured from the movement related cortical potential (MRCP) before and after the experiment. MRCP consisted of the bereitshaftspotential (BP) and negative slope potential (NS) at Cz and C4. Results: Continuous and interrupted tDCS showed a significant difference in the changes in the BP, NS at Cz and C4 compared to the sham tDCS. However, there was no significant difference between the continuous tDCS and interrupted tDCS. Conclusion: The change in cortical activity by continuous and interrupted tDCS results from an improvement in the MRCP. An interrupted tDCS may be a safe and useful modality for stimulating the cortical region.

• The Journal of Korean Physical Therapy
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• v.22 no.4
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• pp.97-101
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• 2010

Purpose: Sensory input is very important for proper performance of human. Two-point discrimination is the most widely used tactile sensory test. The purpose of this study was to find the changes in cortical activation patterns between tactile stimulation and two-point discrimination. Methods: Two healthy subjects participated in our study. fMRI scanning was done during 4 repeated blocks of tactile stimulation and two point discrimination of the right index finger tip. In one block, stimuli were repeated 10 times every three seconds. To determine the changes of cortical neurons during sensory input, intensity index was analyzed. Results: When tactile stimulation of the right index finger tip was completed, only contralateral primary somatosensory area was activated. In contrast, during two-point discrimination, both the primary somatosensory area and ipsilateral supplementary sensory area were activated. Conclusion: During two point discrimination, both primary somatosensory area and ipsilateral supplementary sensory area were activated. Therefore, two-point discrimination is required more complex and conscious activity than tactile stimulation.

• Korean Journal of Biological Psychiatry
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• v.23 no.3
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• pp.89-101
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• 2016

Transcranial magnetic stimulation (TMS) is a safe, noninvasive and useful technique for exploring brain function. Especially, for the study of cognition, the technique can modulate a cognitive performance if the targeted area is engaged, because TMS has an effect on cortical network. The effect of TMS can vary depending on the frequency, intensity, and timing of stimulation. In this paper, we review the studies with TMS targeting various regions for evaluation of cognitive function. Cognitive functions, such as attention, working memory, semantic decision, discrimination and social cognition can be improved or deteriorated according to TMS stimulation protocols. Furthermore, potential therapeutic applications of TMS, including therapy in a variety of illness and research into cortical localization, are discussed.

• Korean Journal of Clinical Laboratory Science
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• v.54 no.2
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• pp.157-162
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• 2022

The purpose of the direct cortical and subcortical stimulation technique is to prevent false positives caused by transcranial electrical motor evoked potentials (TceMEP) in surgery on patients with brain tumors that have occurred around the motor cortex and to preserve the correct mapping of motor areas during surgery and the corticospinal tract. In addition, it reduces the trial and error that occurs during the intraoperative neurophysiological monitoring (INM) process and minimizes the test time, so that accurate information is communicated to the surgeon with quick feedback on the test results. The most important factors of this technique are, first, examination at a stimulus threshold of a certain intensity, and second, maintaining anesthesia depth at an appropriate level to prevent false positives from occurring during surgery. The third is the installation of a multi-level channel recording electrode on the opposite side of the area of operation to measure the TceMEP waveform and the response to direct cortical and subcortical stimulation in as many muscles as possible. If these conditions are maintained, it is possible to predict causes that may occur in other factors, not false positives, from the INM test.

• Journal of Korean Neurosurgical Society
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• v.29 no.7
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• pp.954-958
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• 2000

In the removal of small subcortical lesion in the eloquent area like sensory-motor cortex, the prevention of neurologic deficit is important. We present our technique of identification of M-1, S-1 cortex in a case of subcortical granuloma located in sensorymotor cortex. To accurately localize mass, stereotactic craniotomy was planned. At the beginning of procedure, functional MRI of motor cortex was done with stereotactic headframe in place. Next, the stereotactic craniotomy about 4 cm was done under propofol anesthesia for cortical mapping. After reflection of dura, central sulcus was identified with phase-reversal response of intraoperative SEP(somatosensory evoked potential) of contralateral median nerve. Then the patient was awakened, and direct cortical stimulation was done. We observed the muscle contractions of elbow, hand and fingers and the paresthesia over forearm, hand, fingers on the M-1 and S-1 cortex. Through cortical mapping and stereotactic guidance, we concluded that the mass lie immediately posterior to central sulcus, then the mass was carefully removed through small transsulcal approach, opening about 1 cm of rolandic sulcus.