A reconstruction of the conductive phenomena elicited by transcranial magnetic stimulation in heterogeneous brain tissue.

@article{citeulike:2431997, abstract = {Transcranial magnetic stimulation is an attractive research and possibly therapeutic tool for non-invasive stimulation of brain tissue. However, relatively little is known about the direction, magnitude and distribution of induced fields and current flow in tissue, and optimal setup characteristics remain largely undetermined. Further, the profound influence of brain size and shape as well as of brain tissue irregularity on actual stimulation patterns is unclear. We model the conductive phenomena induced in brain tissue by TMS by solving the quasistatic problem over a realistic head model of 1mm resolution derived from anatomical MRI scans using a finite difference successive overrelaxation procedure. The magnetic field is calculated from digitized coil geometry and realistic stimulator parameters. Stimulation with a symmetrical primary electric field results in electric field and current density distributions which are highly asymmetrical both in magnitude and in direction (i.e. distributed, non-contiguous stimulation peaks, deviation of stimulated area from coil "hot spot", sudden jumps in stimulation intensity and non-zero current flow across tissue interfaces). Knowledge of coil and stimulator specifications alone is hence not sufficient to control stimulation conditions, and a stereotaxic setup coupled with an individually adjusted field solver appears essential in performing reliable TMS studies. Our results bear direct relevance to any application of TMS, both investigative and therapeutic.}, address = {Sezione di Fisica Medica, Facolt\`{a} di Medicina e Chirurgia, Universit\'{a} degli Studi di Roma “Tor Vergata”, Via Montpellier 1, 00133 Roma, Italy.}, author = {Toschi, Nicola and Welt, Tobias and Guerrisi, Maria and Keck, Martin E E. }, citeulike-article-id = {2431997}, doi = {10.1016/j.ejmp.2008.01.005}, issn = {1120-1797}, journal = {Phys Med}, keywords = {model, tms, tms-model}, month = {February}, posted-at = {2008-02-27 01:06:58}, priority = {2}, title = {A reconstruction of the conductive phenomena elicited by transcranial magnetic stimulation in heterogeneous brain tissue.}, url = {http://dx.doi.org/10.1016/j.ejmp.2008.01.005}, year = {2008} }

TY - JOUR ID - citeulike:2431997 L3 - citeulike-article-id:2431997 TI - A reconstruction of the conductive phenomena elicited by transcranial magnetic stimulation in heterogeneous brain tissue. JF - Phys Med AD - Sezione di Fisica Medica, Facoltà di Medicina e Chirurgia, Universitá degli Studi di Roma “Tor Vergata”, Via Montpellier 1, 00133 Roma, Italy. SN - 1120-1797 N2 - Transcranial magnetic stimulation is an attractive research and possibly therapeutic tool for non-invasive stimulation of brain tissue. However, relatively little is known about the direction, magnitude and distribution of induced fields and current flow in tissue, and optimal setup characteristics remain largely undetermined. Further, the profound influence of brain size and shape as well as of brain tissue irregularity on actual stimulation patterns is unclear. We model the conductive phenomena induced in brain tissue by TMS by solving the quasistatic problem over a realistic head model of 1mm resolution derived from anatomical MRI scans using a finite difference successive overrelaxation procedure. The magnetic field is calculated from digitized coil geometry and realistic stimulator parameters. Stimulation with a symmetrical primary electric field results in electric field and current density distributions which are highly asymmetrical both in magnitude and in direction (i.e. distributed, non-contiguous stimulation peaks, deviation of stimulated area from coil "hot spot", sudden jumps in stimulation intensity and non-zero current flow across tissue interfaces). Knowledge of coil and stimulator specifications alone is hence not sufficient to control stimulation conditions, and a stereotaxic setup coupled with an individually adjusted field solver appears essential in performing reliable TMS studies. Our results bear direct relevance to any application of TMS, both investigative and therapeutic. KW - model KW - tms KW - tms-model AU - Toschi, Nicola AU - Welt, Tobias AU - Guerrisi, Maria AU - Keck, Martin E PY - 2008/02/22/ UR - http://dx.doi.org/10.1016/j.ejmp.2008.01.005 ER -