Optimized APPS-tDCS electrode position, size, and distance doubles the on-target stimulation magnitude in 3000 electric field models
Abstract Transcranial direct current stimulation (tDCS) is a widely used noninvasive brain stimulation technique with mixed results to date. A potential solution is to apply more efficient stimulation to ensure that each participant receives sufficient cortical activation. In this four-part study, w...
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| Format: | Article |
| Language: | English |
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Nature Portfolio
2022-11-01
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| Series: | Scientific Reports |
| Online Access: | https://doi.org/10.1038/s41598-022-24618-3 |
| _version_ | 1797986883109650432 |
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| author | Kevin A. Caulfield Mark S. George |
| author_facet | Kevin A. Caulfield Mark S. George |
| author_sort | Kevin A. Caulfield |
| collection | DOAJ |
| description | Abstract Transcranial direct current stimulation (tDCS) is a widely used noninvasive brain stimulation technique with mixed results to date. A potential solution is to apply more efficient stimulation to ensure that each participant receives sufficient cortical activation. In this four-part study, we used electric field (E-field) modeling to systematically investigate the cortical effects of conventional and novel tDCS electrode montages, with the goal of creating a new easily adoptable form of tDCS that induces higher and more focal E-fields. We computed 3000 anatomically accurate, MRI-based E-field models using 2 mA tDCS to target the left primary motor cortex in 200 Human Connectome Project (HCP) participants and tested the effects of: 1. Novel Electrode Position, 2. Electrode Size, and 3. Inter-Electrode Distance on E-field magnitude and focality. In particular, we examined the effects of placing electrodes surrounding the corticomotor target in the anterior and posterior direction (anterior posterior pad surround tDCS; APPS-tDCS). We found that electrode position, electrode size, and inter-electrode distance all significantly impact the cortical E-field magnitude and focality of stimulation (all p < 0.0001). At the same 2 mA scalp stimulation intensity, APPS-tDCS with smaller than conventional 1 × 1 cm electrodes surrounding the neural target deliver more than double the on-target cortical E-field (APPS-tDCS: average of 0.55 V/m from 2 mA; M1-SO and bilateral M1: both 0.27 V/m from 2 mA) while stimulating only a fraction of the off-target brain regions; 2 mA optimized APPS-tDCS produces 4.08 mA-like cortical E-fields. In sum, this new optimized APPS-tDCS method produces much stronger cortical stimulation intensities at the same 2 mA scalp intensity. APPS-tDCS also more focally stimulates the cortex at the intended target, using simple EEG coordinate locations and without MRI scans. This APPS-tDCS method is adoptable to any existing, commercially available tDCS device and can be used to ensure sufficient cortical activation in each person. Future directions include testing whether APPS-tDCS produces larger and more consistent therapeutic tDCS effects. |
| first_indexed | 2024-04-11T07:38:51Z |
| format | Article |
| id | doaj.art-cd240cad249f4136b8c2ddf78c89bdd3 |
| institution | Directory Open Access Journal |
| issn | 2045-2322 |
| language | English |
| last_indexed | 2024-04-11T07:38:51Z |
| publishDate | 2022-11-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | Scientific Reports |
| spelling | doaj.art-cd240cad249f4136b8c2ddf78c89bdd32022-12-22T04:36:38ZengNature PortfolioScientific Reports2045-23222022-11-0112111510.1038/s41598-022-24618-3Optimized APPS-tDCS electrode position, size, and distance doubles the on-target stimulation magnitude in 3000 electric field modelsKevin A. Caulfield0Mark S. George1Brain Stimulation Laboratory, Department of Psychiatry, Medical University of South CarolinaBrain Stimulation Laboratory, Department of Psychiatry, Medical University of South CarolinaAbstract Transcranial direct current stimulation (tDCS) is a widely used noninvasive brain stimulation technique with mixed results to date. A potential solution is to apply more efficient stimulation to ensure that each participant receives sufficient cortical activation. In this four-part study, we used electric field (E-field) modeling to systematically investigate the cortical effects of conventional and novel tDCS electrode montages, with the goal of creating a new easily adoptable form of tDCS that induces higher and more focal E-fields. We computed 3000 anatomically accurate, MRI-based E-field models using 2 mA tDCS to target the left primary motor cortex in 200 Human Connectome Project (HCP) participants and tested the effects of: 1. Novel Electrode Position, 2. Electrode Size, and 3. Inter-Electrode Distance on E-field magnitude and focality. In particular, we examined the effects of placing electrodes surrounding the corticomotor target in the anterior and posterior direction (anterior posterior pad surround tDCS; APPS-tDCS). We found that electrode position, electrode size, and inter-electrode distance all significantly impact the cortical E-field magnitude and focality of stimulation (all p < 0.0001). At the same 2 mA scalp stimulation intensity, APPS-tDCS with smaller than conventional 1 × 1 cm electrodes surrounding the neural target deliver more than double the on-target cortical E-field (APPS-tDCS: average of 0.55 V/m from 2 mA; M1-SO and bilateral M1: both 0.27 V/m from 2 mA) while stimulating only a fraction of the off-target brain regions; 2 mA optimized APPS-tDCS produces 4.08 mA-like cortical E-fields. In sum, this new optimized APPS-tDCS method produces much stronger cortical stimulation intensities at the same 2 mA scalp intensity. APPS-tDCS also more focally stimulates the cortex at the intended target, using simple EEG coordinate locations and without MRI scans. This APPS-tDCS method is adoptable to any existing, commercially available tDCS device and can be used to ensure sufficient cortical activation in each person. Future directions include testing whether APPS-tDCS produces larger and more consistent therapeutic tDCS effects.https://doi.org/10.1038/s41598-022-24618-3 |
| spellingShingle | Kevin A. Caulfield Mark S. George Optimized APPS-tDCS electrode position, size, and distance doubles the on-target stimulation magnitude in 3000 electric field models Scientific Reports |
| title | Optimized APPS-tDCS electrode position, size, and distance doubles the on-target stimulation magnitude in 3000 electric field models |
| title_full | Optimized APPS-tDCS electrode position, size, and distance doubles the on-target stimulation magnitude in 3000 electric field models |
| title_fullStr | Optimized APPS-tDCS electrode position, size, and distance doubles the on-target stimulation magnitude in 3000 electric field models |
| title_full_unstemmed | Optimized APPS-tDCS electrode position, size, and distance doubles the on-target stimulation magnitude in 3000 electric field models |
| title_short | Optimized APPS-tDCS electrode position, size, and distance doubles the on-target stimulation magnitude in 3000 electric field models |
| title_sort | optimized apps tdcs electrode position size and distance doubles the on target stimulation magnitude in 3000 electric field models |
| url | https://doi.org/10.1038/s41598-022-24618-3 |
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