scholarly journals Focality Oriented Selection of Current Dose for Transcranial Direct Current Stimulation

2021 ◽  
Author(s):  
Rajan Kashyap ◽  
Sagarika Bhattacharjee ◽  
Ramaswamy Arumugam ◽  
Rose Dawn Bharath ◽  
Kaviraja Udupa ◽  
...  
Keyword(s):  
Direct Current ◽  
Current Density ◽  
Transcranial Direct Current Stimulation ◽  
Age Groups ◽  
Region Of Interest ◽  
Average Current Density ◽  
Peak Region ◽  
Direct Current Stimulation ◽  
Reference Space ◽  
The Brain

Background: In Transcranial Direct Current Stimulation (tDCS) the injected current gets distributed across the brain areas. The motive is to stimulate the target region-of-interest (ROI), while minimizing the current in non-target ROIs. For this purpose, determining the appropriate current-dose for an individual is difficult. Aim: To introduce Dose-Target-Determination-Index (DTDI) to quantify the focality of tDCS and examine the dose-focality relationship in three different populations. Method: Here, we extended our previous toolbox i-SATA to the MNI reference space. After a tDCS montage is simulated for a current-dose, the i-SATA(MNI) computes the average (over voxels) current density for every region in the brain. DTDI is the ratio of average current density at target ROI to the ROI with maximum value (peak region). Ideally target ROI should be the peak region, so DTDI shall range from 0 to 1. Higher the value, the better the dose. We estimated the variation of DTDI within and across individuals using T1-weighted brain images of 45 males and females distributed equally across three age groups- (a) Young adults (20 ≥ x ˂ 40 years), (b) Mid adults (40 ≥ x ˂ 60 years), and (c) Older adults (60 ≥ x ˂ 80 years). DTDI’s were evaluated for the frontal montage with electrodes at F3 and right supra-orbital for three current doses 1mA, 2mA, and 3mA with the target ROI at left middle frontal gyrus. Result: As the dose is incremented, DTDI may show (a) increase, (b) decrease, and (c) no change across the individuals. The focality decreases with age and the decline is stronger in males. Higher current dose at older age can enhance the focality of stimulation. Conclusion: DTDI provides information on which tDCS current dose will optimize the focality of stimulation. DTDI recommended dose should be prioritised based on the age (> 40 years) and sex (especially males) of an individual. The toolbox i-SATA(MNI) is freely available.

scholarly journals Focality-Oriented Selection of Current Dose for Transcranial Direct Current Stimulation

2021 ◽  
Vol 11 (9) ◽  
pp. 940
Author(s):  
Rajan Kashyap ◽  
Sagarika Bhattacharjee ◽  
Ramaswamy Arumugam ◽  
Rose Dawn Bharath ◽  
Kaviraja Udupa ◽  
...  
Keyword(s):  
Older Adults ◽  
Direct Current ◽  
Current Density ◽  
Transcranial Direct Current Stimulation ◽  
Age Groups ◽  
Average Current Density ◽  
Peak Region ◽  
Direct Current Stimulation ◽  
Reference Space ◽  
The Brain

Background: In transcranial direct current stimulation (tDCS), the injected current becomes distributed across the brain areas. The objective is to stimulate the target region of interest (ROI) while minimizing the current in non-target ROIs (the ‘focality’ of tDCS). For this purpose, determining the appropriate current dose for an individual is difficult. Aim: To introduce a dose–target determination index (DTDI) to quantify the focality of tDCS and examine the dose–focality relationship in three different populations. Method: Here, we extended our previous toolbox i-SATA to the MNI reference space. After a tDCS montage is simulated for a current dose, the i-SATA(MNI) computes the average (over voxels) current density for every region in the brain. DTDI is the ratio of the average current density at the target ROI to the ROI with a maximum value (the peak region). Ideally, target ROI should be the peak region, so DTDI shall range from 0 to 1. The higher the value, the better the dose. We estimated the variation of DTDI within and across individuals using T1-weighted brain images of 45 males and females distributed equally across three age groups: (a) young adults (20 ≤ x ˂ 40 years), (b) mid adults (40 ≤ x ˂ 60 years), and (c) older adults (60 ≤ x ˂ 80 years). DTDI’s were evaluated for the frontal montage with electrodes at F3 and the right supraorbital for three current doses of 1 mA, 2 mA, and 3 mA, with the target ROI at the left middle frontal gyrus. Result: As the dose is incremented, DTDI may show (a) increase, (b) decrease, and (c) no change across the individuals depending on the relationship (nonlinear or linear) between the injected tDCS current and the distribution of current density in the target ROI. The nonlinearity is predominant in older adults with a decrease in focality. The decline is stronger in males. Higher current dose at older age can enhance the focality of stimulation. Conclusion: DTDI provides information on which tDCS current dose will optimize the focality of stimulation. The recommended DTDI dose should be prioritized based on the age (>40 years) and sex (especially for males) of an individual. The toolbox i-SATA(MNI) is freely available.

scholarly journals 𝓲-SATA: A MATLAB based toolbox to estimate Current Density generated by Transcranial Direct Current Stimulation in an Individual Brain

2020 ◽  
Author(s):  
Rajan Kashyap ◽  
Sagarika Bhattacharjee ◽  
Ramaswamy Arumugam ◽  
Kenichi Oishi ◽  
John E. Desmond ◽  
...  
Keyword(s):  
Direct Current ◽  
Current Density ◽  
Transcranial Direct Current Stimulation ◽  
Anterior Commissure ◽  
Weak Current ◽  
Posterior Commissure ◽  
Direct Current Stimulation ◽  
Total Current Density ◽  
Magnetic Resonance Imaging Mri ◽  
The Brain

AbstractBackgroundTranscranial Direct Current Stimulation (tDCS) is a technique where a weak current is passed through the electrodes placed on the scalp. The distribution of the electric current induced in the brain due to tDCS is provided by simulation toolbox like Realistic-volumetric-Approach-based-Simulator-for-Transcranial-electric-stimulation (ROAST). However, the procedure to estimate the total current density induced at the target and the intermediary region of the cortex is complex. The Systematic-Approach-for-tDCS-Analysis (SATA) was developed to overcome this problem. However, SATA is limited to standardized headspace only. Here we develop individual-SATA (𝓲-SATA) to extend it to individual head.MethodT1-weighted images of 15 subjects were taken from two Magnetic Resonance Imaging (MRI) scanners of different strengths. Across the subjects, the montages were simulated in ROAST. 𝓲-SATA converts the ROAST output to Talairach space. The x, y and z coordinates of the anterior commissure (AC), posterior commissure (PC), and Mid-Sagittal (MS) points are necessary for the conversion. AC and PC are detected using the acpcdetect toolbox. We developed a method to determine the MS in the image and cross-verified its location manually using BrainSight®.ResultDetermination of points with 𝓲-SATA is fast and accurate. The 𝓲-SATA provided estimates of the current-density induced across an individual’s cortical lobes and gyri as tested on images from two different scanners.ConclusionResearchers can use 𝓲-SATA for customizing tDCS-montages. With 𝓲-SATA it is also easier to compute the inter-individual variation in current-density across the target and intermediary regions of the brain. The software is publicly available.

scholarly journals Multifocal Transcranial Direct Current Stimulation Modulates Resting-State Functional Connectivity in Older Adults Depending on the Induced Current Density

2021 ◽  
Vol 13 ◽  
Author(s):  
Kilian Abellaneda-Pérez ◽  
Lídia Vaqué-Alcázar ◽  
Ruben Perellón-Alfonso ◽  
Cristina Solé-Padullés ◽  
Núria Bargalló ◽  
...  
Keyword(s):  
Older Adults ◽  
Electric Current ◽  
Direct Current ◽  
Current Density ◽  
Transcranial Direct Current Stimulation ◽  
Resting State ◽  
Electric Current Density ◽  
Direct Current Stimulation ◽  
Induced Changes ◽  
The Brain

Combining non-invasive brain stimulation (NIBS) with resting-state functional magnetic resonance imaging (rs-fMRI) is a promising approach to characterize and potentially optimize the brain networks subtending cognition that changes as a function of age. However, whether multifocal NIBS approaches are able to modulate rs-fMRI brain dynamics in aged populations, and if these NIBS-induced changes are consistent with the simulated electric current distribution on the brain remains largely unknown. In the present investigation, thirty-one cognitively healthy older adults underwent two different multifocal real transcranial direct current stimulation (tDCS) conditions (C1 and C2) and a sham condition in a crossover design during a rs-fMRI acquisition. The real tDCS conditions were designed to electrically induce two distinct complex neural patterns, either targeting generalized frontoparietal cortical overactivity (C1) or a detachment between the frontal areas and the posteromedial cortex (C2). Data revealed that the two tDCS conditions modulated rs-fMRI differently. C1 increased the coactivation of multiple functional couplings as compared to sham, while a smaller number of connections increased in C1 as compared to C2. At the group level, C1-induced changes were topographically consistent with the calculated electric current density distribution. At the individual level, the extent of tDCS-induced rs-fMRI modulation in C1 was related with the magnitude of the simulated electric current density estimates. These results highlight that multifocal tDCS procedures can effectively change rs-fMRI neural functioning in advancing age, being the induced modulation consistent with the spatial distribution of the simulated electric current on the brain. Moreover, our data supports that individually tailoring NIBS-based interventions grounded on subject-specific structural data might be crucial to increase tDCS potential in future studies amongst older adults.

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.

Combined brain Fe, Cu, Zn and neurometabolite analysis – a new methodology for unraveling the efficacy of transcranial direct current stimulation (tDCS) in appetite control

Metallomics ◽  
2018 ◽  
Vol 10 (3) ◽  
pp. 397-405
Author(s):  
Agata Ziomber ◽  
Artur Dawid Surowka ◽  
Lucyna Antkiewicz-Michaluk ◽  
Irena Romanska ◽  
Pawel Wrobel ◽  
...  
Keyword(s):  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Appetite Control ◽  
Direct Current Stimulation ◽  
The Brain

A new methodology for a combined Fe, Cu, Zn and neurometabolite analysis in the brain is reported.

Working Memory Training and Transcranial Direct Current Stimulation

2019 ◽  
pp. 105-130
Author(s):  
Jacky Au ◽  
Martin Buschkuehl ◽  
Susanne M. Jaeggi
Keyword(s):  
Working Memory ◽  
Electrical Stimulation ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Working Memory Training ◽  
Memory Training ◽  
Transcranial Electrical Stimulation ◽  
Direct Current Stimulation ◽  
Underlying Mechanisms ◽  
The Brain

The aim of this chapter is to contribute to the discussion of the cognitive neuroscience of brain stimulation. In doing so, the authors emphasize work from their own laboratory that focuses both on working memory training and transcranial direct current stimulation. Transcranial direct current stimulation is one of the most commonly used and extensively researched methods of transcranial electrical stimulation. The chapter focuses on implementation of transcranial direct current stimulation to enhance and inform research on working memory training, and not on the underlying mechanisms of transcranial direct current stimulation. Thus, while respecting the intricacies and unknowns of the inner workings of electrical stimulation on the brain, the chapter relies on the premise that transcranial direct current stimulation is able to directly affect the electrophysiological profile of the brain and provides evidence that this in turn can influence behavior given the right parameters.

High intensity aerobic exercise does not prime the brain for anodal transcranial direct current stimulation

2019 ◽  
Vol 12 (4) ◽  
pp. 1086-1088 ◽  
Author(s):  
Ashlee M. Hendy ◽  
Helen Macpherson ◽  
Nathan D. Nuzum ◽  
Paul A. Della Gatta ◽  
Sarah E. Alexander ◽  
...  
Keyword(s):  
Aerobic Exercise ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
High Intensity ◽  
Direct Current Stimulation ◽  
The Brain

Power spectral parameter variations after transcranial direct current stimulation in a bimanual coordination task

2019 ◽  
pp. 105971231987997 ◽  
Author(s):  
Atefeh Azarpaikan ◽  
HamidReza Taherii Torbati ◽  
Mehdi Sohrabi ◽  
Reza Boostani ◽  
Majid Ghoshuni
Keyword(s):  
Parietal Cortex ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Bimanual Coordination ◽  
Neuronal Membrane ◽  
Membrane Excitability ◽  
Direct Current Stimulation ◽  
Cerebellar Tdcs ◽  
Alpha Beta ◽  
The Brain

Transcranial direct current stimulation (tDCS) can shift neuronal membrane excitability by applying a weak slow electric current to the brain through the scalp. Attendant electroencephalography (EEG) can provide valuable information about the tDCS mechanisms. This study investigated the effects of anodal tDCS on parietal cortex and cerebellum activity to reveal possible modulation of spontaneous oscillatory brain activity. Timing of the tDCS priming protocol in relation to the intervention especially with respect to bimanual coordination task was also studied. EEG activity was measured in 120 healthy participants before and after sessions of anodal stimulation of the parietal cortex and cerebellum to detect the tDCS-induced alterations. Variations of the delta, theta, alpha, beta, and sensorimotor rhythm (SMR) power bands were analyzed using a MATLAB program. The results showed that anodal parietal and cerebellar tDCS cause changes in brain wave frequencies. They also showed an increase in alpha, beta, and SMR power bands during stimulation sessions for during stimulation parietal group ( p ≤ .01). Also, theta, alpha, beta, and SMR power bands were increased in during stimulation cerebellum group in stimulation sessions and 48 h later ( p ≤ .01). Moreover, the results revealed that the tDCS intervention led to a variety of activations in some areas of the brain. Altogether, the cerebellar tDCS during motor task had a significant improvement in off-line learning.

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