title: Validating computationally predicted TMS stimulation areas using direct electrical stimulation in patients with brain tumors near precentral regions.
abstract: The spatial extent of transcranial magnetic stimulation (TMS) is of paramount interest for all studies employing this method. It is generally assumed that the induced electric field is the crucial parameter to determine which cortical regions are excited. While it is difficult to directly measure the electric field, one usually relies on computational models to estimate the electric field distribution. Direct electrical stimulation (DES) is a local brain stimulation method generally considered the gold standard to map structure-function relationships in the brain. Its application is typically limited to patients undergoing brain surgery. In this study we compare the computationally predicted stimulation area in TMS with the DES area in six patients with tumors near precentral regions. We combine a motor evoked potential (MEP) mapping experiment for both TMS and DES with realistic individual finite element method (FEM) simulations of the electric field distribution during TMS and DES. On average, stimulation areas in TMS and DES show an overlap of up to 80%, thus validating our computational physiology approach to estimate TMS excitation volumes. Our results can help in understanding the spatial spread of TMS effects and in optimizing stimulation protocols to more specifically target certain cortical regions based on computational modeling.
authors.affiliation: Department of Clinical Neurophysiology, Georg-August-University, Göttingen, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Opitz
authors.affiliation: Department of Neurosurgery, Georg-August-University, Göttingen, Germany.
authors.forename: Noman
authors.initials: N
authors.lastname: Zafar
authors.affiliation: Department of Neurosurgery, Georg-August-University, Göttingen, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Bockermann
authors.affiliation: Department of Neurosurgery, Georg-August-University, Göttingen, Germany.
authors.forename: Veit
authors.initials: V
authors.lastname: Rohde
authors.affiliation: Department of Clinical Neurophysiology, Georg-August-University, Göttingen, Germany.
authors.forename: Walter
authors.initials: W
authors.lastname: Paulus
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000503:physiopathology*; D003198:Computer Simulation; D004558:Electric Stimulation / Q000379:methods*; D019054:Evoked Potentials, Motor; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008959:Models, Neurological; D009044:Motor Cortex / Q000503:physiopathology*; D009415:Nerve Net / Q000503:physiopathology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D050781:Transcranial Magnetic Stimulation / Q000379:methods*
keywords: Direct electrical stimulation; Finite element method; Motor cortex; Transcranial magnetic stimulation