• Journal of the Korean Academy of Clinical Electrophysiology
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• v.9 no.2
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• pp.19-24
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• 2011

Purpose : This study is to examine the effects of transcranial direct current stimulation on the excitability of the central neuron. Methods : This study selected 24 suitable women in their twenties. A positive electrode of transcranial direct current stimulation was placed on the primary motor area (M1) C4 and a negative electrode was placed on the left supraobital. A stimulation of 0.04mA/$cm^2$ was applied for 20 minutes. H-reflex and V wave used diagnostic electromyography. An active electrode was placed at the muscle belly of the medial gastrocnemius muscle at a prone posture. An electrical stimulation was given to the posterior tibial nerve. Measurements were made before and after the stimulation. All data were analyzed with SPSS 12.0 and between each measuring before and after the change of the H-reflex and V wave amplitude. Results : There were no significant differences in all H wave, M wave, and V wave amplitude before and after transcranial direct current stimulation. There were no significant differences in the change of H/M ratio and V/M ratio before and after transcranial direct current stimulation. Conclusion : We know that transcranial direct current stimulation cannot have an influence on a normal grown-up person's central neuron.

• Journal of Biomedical Engineering Research
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• v.44 no.6
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• pp.377-383
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• 2023

Purpose: There is increasing attention to the application of transcranial direct current stimulation (tDCS) for enhancing cognitive functions in subjects to aging, mild cognitive impairment (MCI), and Alzheimer's disease (AD). Despite varying treatment outcomes in tDCS which depend on the amount of current reaching the brain, there is no general information on the impacts of anatomical features associated with AD on tDCS-induced electric field. Objective: The objective of this study is to examine how AD-related anatomical variation affects the tDCS-induced electric field using computational modeling. Methods: We collected 180 magnetic resonance images (MRI) of AD patients and healthy controls from a publicly available database (Alzheimer's Disease Neuroimaging Initiative; ADNI), and MRIs were divided into female-AD, male-AD, female-normal, and male-normal groups. For each group, segmented brain volumes (cerebrospinal fluid, gray matter, ventricle, rostral middle frontal (RMF), and hippocampus/amygdala complex) using MRI were measured, and tDCS-induced electric fields were simulated, targeting RMF. Results: For segmented brain volumes, significant sex differences were observed in the gray matter and RMF, and considerable disease differences were found in cerebrospinal fluid, ventricle, and hippocampus/amygdala complex. There were no differences in the tDCS-induced electric field among AD and normal groups; however, higher peak values of electric field were observed in the female group than the male group. Conclusions: Our findings demonstrated the presence of sex and disease differences in segmented brain volumes; however, this pattern differed in tDCS-induced electric field, resulting in significant sex differences only. Further studies, we will adjust the brain stimulation conditions to target the deep brain and examine the effects, because of significant differences in the ventricles and deep brain regions between AD and normal groups.

• Journal of The Korean Society of Integrative Medicine
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• v.11 no.2
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• pp.101-108
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• 2023

Purpose : To investigate effects of transcranial directed current stimulus (tDCS) combined with abdominal draw-in maneuver (ADIM) on balance ability and trunk impairment scale of chronic stroke patients. Methods : Twenty-six chronic stroke patients were recruited and twenty-four participated after excluding two patients who met the exclusion criteria. After screening tests, they were randomized through excel program into an experimental group (n = 12) to apply a tDCS combined with ADIM and a control group (n = 12) to apply a sham tDCS with ADIM. The intervention lasted three times a week for six weeks. To compare tDCS intervention effects, trunk impairment scale and balance ability were measured. Comparisons between experimental and control groups were statistically processed using an independent t-test and comparisons within groups were statistically processed using a paired t-test. Results : The experimental group showed significant increases of pre- and post-intervention medial lateral velocity, anterior posterior velocity and area of balance ability, and trunk impairment scale (p<.05). The control group showed significant increases in pre- and post-intervention medial lateral velocity of balance ability and trunk impairment scale (p< .05). The experimental group showed significant increases of medial lateral velocity of balance ability and trunk impairment scale compared to the control group (p<.05). Conclusion : Results of this study suggest that tDCS combined with ADIM for chronic stroke patients can be effective in improving medial lateral velocity of balance ability and trunk impairment scale. Thus, tDCS can be used as an effective treatment protocol for trunk rehabilitation of chronic stroke patients.

• Journal of Biomedical Engineering Research
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• v.32 no.4
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• pp.305-311
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• 2011

For effective stimulation with tDCS, spatial focality of induced electrical field(EF) and current density(CD) is one of the important factors to be considered. Recently, there have been some studies to improve the spatial focality via different types of electrodes and their new configurations: some improvements using ring electrodes were reported over the conventional pad electrodes. However, most of these studies assumed isotropic conductivities in the head. In this work, we have investigated the effect of tissue anisotropy on the spatial focality of tDCS with the 4 + 1 ring electrode configuration via a 3-D high-resolution finite element(FE) head model with anisotropic conductivities in the skull and white matter. By examining the profiles of the induced EF from the head models with isotropic and anisotropic conductivities respectively, we found that the spatial focality of the induced EF significantly drops and get diffused due to tissue anisotropy. Our analysis suggests that it is critical to incorporate tissue anisotropy in the effective stimulation of the brain via tDCS.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.11 no.1
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• pp.31-38
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• 2013

Purpose : This study was to identify the effect of cognitive reaction following inactive electrode placement when applying anodal transcranial direct current stimulation over the primary motor cortex. Methods : For this study a total of 28 stroke patients participated. Before applying transcranial direct current stimulation, cognitive reaction was measured (P300 of event related potential, cognitive reaction time), and subjects were randomly assigned to two group. Transcranial direct current stimulation was applied to the scalp with an intensity of $0.04mA/cm^2$ for 15 minutes. All subjects were given an anode transcranial direct current stimulation over the primary motor area and inactive electrodes over the deltoid muscle (group I) and supra-orbital area (group II). Cognitive reactions were measured after applying transcranial direct current stimulation. Results : For this study a total of 28 stroke patients participated. Before applying transcranial direct current stimulation, cognitive reaction was measured (P300 of event related potential, cognitive reaction time), and subjects were randomly assigned to two group. Transcranial direct current stimulation was applied to the scalp with an intensity of $0.04mA/cm^2$ for 15 minutes. All subjects were given an anode transcranial direct current stimulation over the primary motor area and inactive electrodes over the deltoid muscle (group I) and supra-orbital area (group II). Cognitive reactions were measured after applying transcranial direct current stimulation. Conclusion : Thus transcranial direct current stimulation on the primary motor area may help cognitive reaction regardless of inactive electrode placement.

• Korean Journal of Cognitive Science
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• v.26 no.4
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• pp.393-433
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• 2015

Creativity refers to the ability to generate novel and useful ideas. Understanding the mechanism of creativity and its enhancement is important in order to solve major problems of the modern society and to improve the wellness of mankind. Creativity is a highly heterogeneous and complex ability which should not be conceptualized as a single entity. Thus, the current literature on creativity is based on a component process approach to creativity. The present study introduces cognitive neuroscience research studying the mechanism of divergent thinking, insight, relational thinking and artistic creativity which are the major components of creativity. Based on an expansive review, the early hypothesis of hemispheric asymmetry emphasizing the importance of the right as opposed to the left hemisphere is not supported by scientific evidence. In addition, there is no consensus or consistency on which specific brain region is related to a certain component of creativity. In fact, there is a mixture of studies reporting involvement of various brain regions across all four lobes of the brain. This inconsistency in the literature most likely reflects heterogeneity of the component processes of creativity and sensitivity of the neural response to differences across tasks and cognitive strategy. The present study introduces examples of representative studies reporting seminal findings on the neural basis and the enhancement of creativity based on innovative methodology. In addition, we discuss limitations of the current cognitive neuroscience approach to creativity and present directions for future research.

• Journal of Sleep Medicine
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• v.15 no.2
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• pp.37-42
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• 2018

Objectives: To assess the effect and safety of transcranial direct-current stimulation (tDCS) in primary chronic insomnia. Methods: A one-month, double-blind, randomized, sham-controlled trial was performed. A total of 7 patients with primary chronic insomnia received tDCS using anodal (n=3), cathodal (n=2), or sham stimulation (n=2). They were followed up at 1 week and 1 month after treatment. The primary outcome measures included improvement in total sleep time (TST), sleep latency (SL), and sleep efficiency (SE) at 1 month follow-up. Results: TST and SE were improved with tDCS at 1 month follow-up in all patients (100%) of the anodal group, one (50%) of the cathodal group, and one (50%) of the sham group. tDCS improved SL at 1 month follow-up in two patients (67%) of the anodal group, one (50%) of the cathodal group, and none (0%) of the sham group. With respect to adverse events, transient itching sensation occurred in one patient of the anodal group. None of the other groups reported adverse events. Conclusions: Our results suggest that tDCS may be effective and safe for treatment of primary chronic insomnia. A larger controlled study needs to be further investigated.

• Korean Journal of Applied Biomechanics
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• v.32 no.3
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• pp.94-102
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• 2022

Objective: The purpose of this study was to investigate the effect of acute transcranial direct current stimulation (tDCS) on the isokinetic muscular endurance of the lower extremity for young adults. Method: Thirteen young adults performed isokinetic fatigue tasks for two experimental conditions including real tDCS and sham stimulation protocols. Before and after the task, the tensiomyography was used for evaluating muscle contraction characteristics of vastus medialis and semitendinosus. Paired t-test was performed to compare the fatigue index, changes in maximum radial displacement (∆Dm), delay time (∆Tc), and velocity of contraction (∆Vc) between tDCS conditions. Results: We found no significant differences in the fatigue index between real and sham conditions. In addition, the analyses identified no significant different values of ∆Dm, ∆Tc, and ∆Vc in the vastus medialis and semitendinosus between real and sham conditions. Conclusion: These findings suggest that the tDCS protocols may have no acute effect on lower limb muscle endurance for young adults. Future studies should consider the long-term effects of repetitive tDCS sessions, various stimulation positions, exercise tasks, and participant characteristics to more clearly understand the effect of tDCS on muscle endurance of lower extremities.