A computational pipeline to determine lobular electric field distribution during cerebellar transcranial direct current stimulation

Abstract

Objective: Cerebellar transcranial direct current stimulation (ctDCS) is challenging due to the complexity of the cerebellar structure. Therefore, our objective is to develop a freely available computational pipeline to perform cerebellar atlas-based electric field analysis using magnetic resonance imaging (MRI) guided subject-specific head modeling.Methods: We present a freely available computational pipeline to determine subject-specific lobular electric field distribution during ctDCS. The computational pipeline can isolate subject-specific cerebellar lobules based on a spatially unbiased atlas (SUIT) for the cerebellum, and then calculates the lobular electric field distribution during ctDCS. The computational pipeline was tested in a case study using a subject-specific head model as well as using a Colin 27 Average Brain. The 5cmx5cm anode was placed 3 cm lateral to inion, and the same sized cathode was placed on the contralateral supraorbital area (called Manto montage) and buccinators muscle (called Celnik montage). A 4x1 HD-ctDCS electrode montage was also implemented for a comparison using analysis of variance (ANOVA).Results: Eta-squared effect size after three-way ANOVA for electric field strength was 0.05 for lobule, 0.00 for montage, 0.04 for head model, 0.01 for lobule*montage interaction, 0.01 for lobule* head model interaction, and 0.00 for montage*head model interaction in case of Enorm. Here, the electric field strength of both the Celnik and the Manto montages affected the lobules Crus II, VIIb, VIII, IX of the targeted cerebellar hemispheres while Manto montage had more bilateral effect. The HD-ctDCS montage primarily affected the lobules Crus I, Crus II, VIIb of the targeted cerebellar hemisphere. Our freely available computational modeling approach to analyze subject-specific lobular electric field distribution during ctDCS provided an insight into healthy human anodal ctDCS results 2.1. Computational Modeling Pipeline 2.1.1. MRI data acquisition and subject-specific head model creation

Investigating the Feasibility of Cerebellar Transcranial Direct Current Stimulation to facilitate Post-Stroke Overground Gait Performance in Chronic Stroke: a partial least-squares regression approach

“…Here, isotropic conductivity used for the different brain tissues [46] were (in S/m): Scalp=0.465; Skull=0.01; CSF=1.654; GM=0.276; WM=0.126. For further details on the head modeling, please refer to our prior works [22], [23].…”

“…In this feasibility study, we optimized cerebellar lobule-speci c electric eld distribution using our Cerebellar Lobules Optimal Stimulation (CLOS) pipeline [22] for deep ctDCS of the dentate nucleus (as well as both the lobes of the cerebellum) and the lower-limb representations (lobules VIIb-IX) in the cerebellum [23]. It is important to investigate the role of ctDCS in post-stroke gait rehabilitation [20] since "the motor cortex retains what the cerebellum learns [24]", i.e., unlike the primary motor cortex stimulation that may increase the retention of newly learned visuomotor skills, ctDCS may facilitate motor adaptation and early-stage error-based learning during repetitive balance training [24].…”

“…Also, anodal ctDCS of combined anterior and posterior lobes of the cerebellum resulted in a signi cant decrease in the root mean square error post-intervention than in the baseline. Therefore, we found it crucial to investigate the behavioral effects of the lobular electric eld distribution due to various ctDCS montages that are optimized using a computational pipeline [22].…”

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

“…In this computational modeling study, we postulate that the investigation of the changes in the electrical field distribution across cerebellar lobules during healthy aging will help us to better understand the lobule-specific dosage considerations of ctDCS in older adults. Therefore, we investigated the lobular electric field distribution across eighteen age groups from 18 to 89 years of age by applying our published computational pipeline (Rezaee and Dutta, 2019) on age-appropriate human brain magnetic resonance imaging (MRI) templates (http://jerlab.psych.sc.edu/NeurodevelopmentalMRIDatabase/). Our computational modeling study leveraged Realistic volumetric Approach to Simulate Transcranial Electric Stimulation (ROAST) (Huang et al, 2018) for head modeling and finite element analysis (FEA), and then applied Spatially Unbiased Infratentorial Template for the Cerebellum (SUIT) atlas (Diedrichsen et al, 2009) to divide the cerebellum into 28 lobules.…”

“…For the first four age-groups, the age intervals were six months (i.e., 18-18.5-19-19.5 years of age), and then from age 20 to 89 years for the next fourteen age-groups, the average T1-weighted MRI were grouped by an interval of 5 years. We applied our computational pipeline (Rezaee and Dutta, 2019) (Penny et al, 2011), Iso2mesh (Fang and Boas, 2009), and getDP (Dular et al, 1998). Here, average T1-weighted MRI for each age group was used to construct the age-group specific head models for finite element analysis (FEA).…”