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 Transcranial direct current stimulation over the right DLPFC selectively modulates subprocesses in working memory

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4906 ◽  
Author(s):  
Jiarui Wang ◽  
Jinhua Tian ◽  
Renning Hao ◽  
Lili Tian ◽  
Qiang Liu
Keyword(s):  
Working Memory ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Working Memory Capacity ◽  
Brain Regions ◽  
Cortical Activation ◽  
Direct Current Stimulation ◽  
Difficult Condition ◽  
Cathodal Tdcs ◽  
The Right

Background Working memory, as a complex system, consists of two independent components: manipulation and maintenance process, which are defined as executive control and storage process. Previous studies mainly focused on the overall effect of transcranial direct current stimulation (tDCS) on working memory. However, little has been known about the segregative effects of tDCS on the sub-processes within working memory. Method Transcranial direct current stimulation, as one of the non-invasive brain stimulation techniques, is being widely used to modulate the cortical activation of local brain areas. This study modified a spatial n-back experiment with anodal and cathodal tDCS exertion on the right dorsolateral prefrontal cortex (DLPFC), aiming to investigate the effects of tDCS on the two sub-processes of working memory: manipulation (updating) and maintenance. Meanwhile, considering the separability of tDCS effects, we further reconfirmed the causal relationship between the right DLPFC and the sub-processes of working memory with different tDCS conditions. Results The present study showed that cathodal tDCS on the right DLPFC selectively improved the performance of the modified 2-back task in the difficult condition, whereas anodal tDCS significantly reduced the performance of subjects and showed an speeding-up tendency of response time. More precisely, the results of discriminability index and criterion showed that only cathodal tDCS enhanced the performance of maintenance in the difficult condition. Neither of the two tDCS conditions affected the performance of manipulation (updating). Conclusion These findings provide evidence that cathodal tDCS of the right DLPFC selectively affects maintenance capacity. Besides, cathodal tDCS also serves as an interference suppressor to reduce the irrelevant interference, thereby indirectly improving the working memory capacity. Moreover, the right DLPFC is not the unique brain regions for working memory manipulation (updating).

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.

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.

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

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.

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