Neuroscience 2004 Abstract
| Presentation Number: | 693.13 |
|---|---|
| Abstract Title: | MRI characterization of transcranial magnetic stimulation (TMS) fields. |
| Authors: |
Kirschen, M. P.*1,2
; Chen, S. H. A.1
; Desmond, J. E.1,2
; Fahrig, R.1
1Dept. of Radiology, Stanford Univ. Sch. of Med., Stanford, CA 2Neurosciences Program, Stanford Univ. Sch. of Med., Stanford, CA |
| Primary Theme and Topics |
Cognition and Behavior - Human Cognition, Behavior, and Anatomy -- Working memory |
| Secondary Theme and Topics | Techniques in Neuroscience<br />- Data analysis, physiological methods, statistics |
| Session: |
693. Imaging Techniques: fMRI and Other Poster |
| Presentation Time: | Tuesday, October 26, 2004 8:00 AM-9:00 AM |
| Location: | San Diego Convention Center - Hall A-H, Board # FFF17 |
| Keywords: | MAPPING, LOCALIZATION |
Transcranial magnetic stimulation (TMS) is a brain stimulation technique that involves passing a powerful and rapidly changing current through a coil that is placed on the scalp. The induced magnetic field passes unimpeded through the skull and transiently disrupts neural circuitry. TMS is an emerging technology which is being used to investigate a wide range of behavioral phenomena, including motor control, visual processing and memory. Although functional MRI guidance and infrared tracking have improved the localization of TMS, the strength and distribution of the induced magnetic fields have not yet been accurately characterized. To localize the magnetic field of a 110mm double-cone TMS coil, we imaged a water-filled spherical phantom with TMS application in 3 orthogonal planes in a 0.5 T open MR scanner. A standard 2D fast gradient echo sequence was used to obtain images of phase evolution due to application of a constant 50 mA current to the TMS coil (TE = 7.8 and 8.8 ms, TR = 150 ms, voxel size ~ 3 mm, with and without current). Phase differences between baseline and TMS application demonstrated the expected magnitude and distribution of field lines. Results will be discussed in terms of the maximum field strength with respect to the apex of the coil along with the distribution of the induced magnetic fields, with appropriate scaling to provide the true field during normal use of the coil at large, transient currents. In addition, comparisons of field distribution in phantom vs. actual brain volumes will be described from in vivo measurements made from normal healthy volunteers. These results will increase our understanding of TMS localization and provide a possible method for characterizing depth and extent of stimulation.
Supported by NIH/NIMH MH60234 and Stanford MSTP
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2004 Neuroscience Meeting Planner. San Diego, CA: Society for Neuroscience, 2004. Online.
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