COMPUTATIONAL MODELING OF TRANSCRANIAL DIRECT CURRENT STIMULATION IN THE CHILD BRAIN: IMPLICATIONS FOR THE TREATMENT OF REFRACTORY CHILDHOOD FOCAL EPILEPSY

2014 ◽  
Vol 24 (02) ◽  
pp. 1430006 ◽  
Author(s):  
MARTA PARAZZINI ◽  
SERENA FIOCCHI ◽  
ILARIA LIORNI ◽  
ALBERTO PRIORI ◽  
PAOLO RAVAZZANI
Keyword(s):  
Electric Field ◽  
Computational Modeling ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Focal Epilepsy ◽  
Brain Area ◽  
Epileptiform Activity ◽  
Brain Regions ◽  
Direct Current Stimulation ◽  
The Brain

Transcranial direct current stimulation (tDCS) was recently proposed for the treatment of epilepsy. However, the electrode arrangement for this case is debated. This paper analyzes the influence of the position of the anodal electrode on the electric field in the brain. The simulation shows that moving the anode from scalp to shoulder does influence the electric field not only in the cortex, but also in deeper brain regions. The electric field decreases dramatically in the brain area without epileptiform activity.

High-Definition Transcranial Direct Current Stimulation Improves Delayed Memory in Alzheimer’s Disease Patients: A Pilot Study Using Computational Modeling to Optimize Electrode Position

2021 ◽  
pp. 1-17
Author(s):  
Ingrid Daae Rasmussen ◽  
Nya Mehnwolo Boayue ◽  
Matthias Mittner ◽  
Martin Bystad ◽  
Ole K. Grnli ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Electric Field ◽  
Computational Modeling ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Cortical Atrophy ◽  
Brain Anatomy ◽  
High Definition ◽  
Direct Current Stimulation

Background: The optimal stimulation parameters when using transcranial direct current stimulation (tDCS) to improve memory performance in patients with Alzheimer’s disease (AD) are lacking. In healthy individuals, inter-individual differences in brain anatomy significantly influence current distribution during tDCS, an effect that might be aggravated by variations in cortical atrophy in AD patients. Objective: To measure the effect of individualized HD-tDCS in AD patients. Methods: Nineteen AD patients were randomly assigned to receive active or sham high-definition tDCS (HD-tDCS). Computational modeling of the HD-tDCS-induced electric field in each patient’s brain was analyzed based on magnetic resonance imaging (MRI) scans. The chosen montage provided the highest net anodal electric field in the left dorsolateral prefrontal cortex (DLPFC). An accelerated HD-tDCS design was conducted (2 mA for 3×20 min) on two separate days. Pre- and post-intervention cognitive tests and T1 and T2-weighted MRI and diffusion tensor imaging data at baseline were analyzed. Results: Different montages were optimal for individual patients. The active HD-tDCS group improved significantly in delayed memory and MMSE performance compared to the sham group. Five participants in the active group had higher scores on delayed memory post HD-tDCS, four remained stable and one declined. The active HD-tDCS group had a significant positive correlation between fractional anisotropy in the anterior thalamic radiation and delayed memory score. Conclusion: HD-tDCS significantly improved delayed memory in AD. Our study can be regarded as a proof-of-concept attempt to increase tDCS efficacy. The present findings should be confirmed in larger samples.

scholarly journals Optimizing transcranial direct current stimulation (tDCS) electrode position, size, and distance doubles the on-target cortical electric field: Evidence from 3000 Human Connectome Project models

2021 ◽  
Author(s):  
Kevin A. Caulfield ◽  
Mark S. George
Keyword(s):  
Electric Field ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Brain Regions ◽  
Cortical Activation ◽  
Electrode Position ◽  
Stimulation Intensity ◽  
Direct Current Stimulation ◽  
Field Evidence ◽  
Human Connectome Project

Transcranial direct current stimulation (tDCS) is a widely used noninvasive brain stimulation technique with mixed results and no FDA-approved therapeutic indication to date. So far, thousands of published tDCS studies have placed large scalp electrodes directly over the intended brain target and delivered the same stimulation intensity to each person. Inconsistent therapeutic results may be due to insufficient cortical activation in some individuals and the inability to determine an optimal dose. Here, we computed 3000 MRI-based electric field models in 200 Human Connectome Project (HCP) participants, finding that the largely unexamined variables of electrode position, size, and between-electrode distance significantly impact the delivered cortical electric field magnitude. At the same scalp stimulation intensity, smaller electrodes surrounding the neural target deliver more than double the on-target cortical electric field while stimulating only a fraction of the off-target brain regions. This new optimized tDCS method can ensure sufficient cortical activation in each person and could produce larger and more consistent behavioral effects in every prospective research and transdiagnostic clinical application of tDCS.

scholarly journals Lobule-specific dosage considerations for cerebellar transcranial direct current stimulation during healthy aging – a computational modeling study using age-specific MRI templates

2019 ◽  
Author(s):  
Zeynab Rezaee ◽  
Anirban Dutta
Keyword(s):  
Electric Field ◽  
Computational Modeling ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Healthy Aging ◽  
Cerebellar Hemisphere ◽  
World Population ◽  
Age Group ◽  
Direct Current Stimulation ◽  
Crus I

AbstractThe world population aged 60 years and older is expected to double between 2015 and 2050. Aging is associated with a decline in cognitive and motor performances which are a part of geriatric syndromes. Aging is also associated with the loss of cerebellar volume where the cerebellum has a considerable contribution in cognitive and motor functions. Therefore, cerebellar transcranial direct current stimulation (ctDCS) has been proposed to study and facilitate cerebellar function during aging. However, the one-size-fits-all approach used for ctDCS can lead to variability in the cerebellar lobule-specific dosing due to age-related changes in the cerebellar structure. Therefore, we investigated lobular electric field (EF) distribution during healthy aging for age groups of 18 to 89 years where computational modeling was based on age-appropriate human brain magnetic resonance imaging (MRI) templates (http://jerlab.psych.sc.edu/NeurodevelopmentalMRIDatabase/). A fully automated open-source pipeline (Realistic vOlumetric-Approach to Simulate Transcranial Electric Stimulation – ROAST) was used for the age-group specific EF modeling. Then, we extracted the EF distribution at the 28 cerebellar lobules based on a spatially unbiased atlas (SUIT) for the cerebellum. Our computational results showed that the EF strength increased significantly at certain important cerebellar lobules (e.g., Crus I and Crus II relevant for cognitive function) contralateral (contra) to the targeted (ipsi) cerebellar hemisphere at an older age that reduced the ctDCS specificity. Specifically, two-way ANOVA showed that the lobules as well as the age-group (and their interaction term) had a significant effect (p<0.01). Post-hoc multiple comparison tests at Alpha=0.01 using Bonferroni critical values showed that Right (Ipsi) Crus I, Right (Ipsi) Crus II, Right (Ipsi) VI, Vermis VIIb, Vermis VIIIa, Right (Ipsi) VIIb, Left (Contra) VIIIb, Left (Contra) IX, Right (Ipsi) VIIIa, Right (Ipsi) VIIIb, Vermis VIIIb, Right (Ipsi) IX, and Vermis IX, and the age-group 18, 18.5, 19, 20-24, 45-49, 50-54, 70-74, 75-79, 85-89 years experienced higher electric field strength (>0.11V/m). Since there is a dichotomy between the sensorimotor cerebellum and the cognitive cerebellum, therefore, subject-specific MRI based head modeling for lobule-specific dosage considerations will be necessary for clinical translation of ctDCS to address geriatric cerebellar syndromes.

scholarly journals Multiscale Coupling of Transcranial Direct Current Stimulation to Neuron Electrodynamics: Modeling the Influence of the Transcranial Electric Field on Neuronal Depolarization

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Edward T. Dougherty ◽  
James C. Turner ◽  
Frank Vogel
Keyword(s):  
Electric Field ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Three Dimensional ◽  
Human Head ◽  
Multiscale Model ◽  
Medical Intervention ◽  
Medical Community ◽  
Computational Grids ◽  
Direct Current Stimulation

Transcranial direct current stimulation (tDCS) continues to demonstrate success as a medical intervention for neurodegenerative diseases, psychological conditions, and traumatic brain injury recovery. One aspect of tDCS still not fully comprehended is the influence of the tDCS electric field on neural functionality. To address this issue, we present a mathematical, multiscale model that couples tDCS administration to neuron electrodynamics. We demonstrate the model’s validity and medical applicability with computational simulations using an idealized two-dimensional domain and then an MRI-derived, three-dimensional human head geometry possessing inhomogeneous and anisotropic tissue conductivities. We exemplify the capabilities of these simulations with real-world tDCS electrode configurations and treatment parameters and compare the model’s predictions to those attained from medical research studies. The model is implemented using efficient numerical strategies and solution techniques to allow the use of fine computational grids needed by the medical community.

Converging Evidence That Neural Plasticity Underlies Transcranial Direct-Current Stimulation

2021 ◽  
Vol 33 (1) ◽  
pp. 146-157
Author(s):  
Chong Zhao ◽  
Geoffrey F. Woodman
Keyword(s):  
Visual Search ◽  
Direct Current ◽  
Neural Plasticity ◽  
Transcranial Direct Current Stimulation ◽  
Time Course ◽  
Memory Task ◽  
Long Term Memory ◽  
Visual Stream ◽  
Direct Current Stimulation ◽  
The Brain

It is not definitely known how direct-current stimulation causes its long-lasting effects. Here, we tested the hypothesis that the long time course of transcranial direct-current stimulation (tDCS) is because of the electrical field increasing the plasticity of the brain tissue. If this is the case, then we should see tDCS effects when humans need to encode information into long-term memory, but not at other times. We tested this hypothesis by delivering tDCS to the ventral visual stream of human participants during different tasks (i.e., recognition memory vs. visual search) and at different times during a memory task. We found that tDCS improved memory encoding, and the neural correlates thereof, but not retrieval. We also found that tDCS did not change the efficiency of information processing during visual search for a certain target object, a task that does not require the formation of new connections in the brain but instead relies on attention and object recognition mechanisms. Thus, our findings support the hypothesis that direct-current stimulation modulates brain activity by changing the underlying plasticity of the tissue.

Determinants of the electric field during transcranial direct current stimulation

NeuroImage ◽  
2015 ◽  
Vol 109 ◽  
pp. 140-150 ◽  
Author(s):  
Alexander Opitz ◽  
Walter Paulus ◽  
Susanne Will ◽  
Andre Antunes ◽  
Axel Thielscher
Keyword(s):  
Electric Field ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Direct Current Stimulation

scholarly journals Functional Network Alterations as Markers for Predicting the Treatment Outcome of Cathodal Transcranial Direct Current Stimulation in Focal Epilepsy

2021 ◽  
Vol 15 ◽  
Author(s):  
Jiaxin Hao ◽  
Wenyi Luo ◽  
Yuhai Xie ◽  
Yu Feng ◽  
Wei Sun ◽  
...  
Keyword(s):  
Treatment Outcome ◽  
Prediction Model ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Path Length ◽  
Focal Epilepsy ◽  
Functional Network ◽  
Functional Networks ◽  
Direct Current Stimulation ◽  
The Mean

Background and PurposeTranscranial direct current stimulation (tDCS) is an emerging non-invasive neuromodulation technique for focal epilepsy. Because epilepsy is a disease affecting the brain network, our study was aimed to evaluate and predict the treatment outcome of cathodal tDCS (ctDCS) by analyzing the ctDCS-induced functional network alterations.MethodsEither the active 5-day, −1.0 mA, 20-min ctDCS or sham ctDCS targeting at the most active interictal epileptiform discharge regions was applied to 27 subjects suffering from focal epilepsy. The functional networks before and after ctDCS were compared employing graph theoretical analysis based on the functional magnetic resonance imaging (fMRI) data. A support vector machine (SVM) prediction model was built to predict the treatment outcome of ctDCS using the graph theoretical measures as markers.ResultsOur results revealed that the mean clustering coefficient and the global efficiency decreased significantly, as well as the characteristic path length and the mean shortest path length at the stimulation sites in the fMRI functional networks increased significantly after ctDCS only for the patients with response to the active ctDCS (at least 20% reduction rate of seizure frequency). Our prediction model achieved the mean prediction accuracy of 68.3% (mean sensitivity: 70.0%; mean specificity: 67.5%) after the nested cross validation. The mean area under the receiver operating curve was 0.75, which showed good prediction performance.ConclusionThe study demonstrated that the response to ctDCS was related to the topological alterations in the functional networks of epilepsy patients detected by fMRI. The graph theoretical measures were promising for clinical prediction of ctDCS treatment outcome.

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