P076 A beagle model for understanding tDCS effects

Abstract

Introduction To characterize the efficacy of transcranial direct current stimulation (tDCS), various methods have been performed; particularly, the animal studies have conducted to investigate the behavioral or physiological effects of tDCS. A cost-effective computational study may demonstrate the detailed mechanism of tDCS by computing the stimulus-induced electric field (EF) distributions in the brain. Objective For better understanding on animal tDCS study, we constructed 3D finite element model in beagle and estimated the effects of tDCS under the similar experimental condition.We computed distributions of EF/current density (CD) in beagle brain and investigated the other factors which may be hardly observed in the animal study. Materials & methods In the animal study, a healthy male beagle (15–16 months old and 15.5 kg) received anodal tDCS (1 mA; 15 min) and then the electric potential was measured by electrocorticography electrodes attached directly on the left lateral gyrus (LG). Two pad-type electrodes (1 × 1 cm) were attached at the left prefrontal area (anode) and left occipital area (cathode).To mimic this animal study, we constructed the computational model using CT and MRI of the beagle used in the animal study.In tissue segmentation, we used a digital atlas of the beagle ( Datta and Ritobrato, 2012 ) and Seg3D ( www.seg3d.org ).3D tetrahedron meshes were generated using iso2mesh (Fig.1).The CD distributions were computed by finite element method. Results The left prefrontal and left parietal cortices were affected intensively by induced EF since anode and cathode electrodes were placed closely on those regions, as shown in Fig.2(a).We observed that the left LG was also stimulated more than the right LG. In Fig.2(b), we observed that considerable current flowed along the scalp due to the lowest electrical property of the skull.We understand that some fractional current penetrated the skull properly stimulated the frontal cortex and upper side of the brain. Conclusion As a following animal study, we developed the computational model on beagle.We investigated the effects of tDCS in terms of distribution of CD. In the future, comparison between empirical and computational results will be conducted; we expect that this will be greatly helpful in understanding on mechanism of tDCS effects in the animal study. Download : Download high-res image (111KB) Download : Download full-size image Download : Download high-res image (100KB) Download : Download full-size image