title: Transcranial magnetic stimulation coil with electronically switchable active and sham modes.
abstract: Blinded studies with transcranial magnetic stimulation (TMS) require a valid sham condition. A wide range of sham approaches have been implemented but they have various limitations including residual electric field in the brain, inadequate reproduction of auditory and cutaneous sensations, and/or need for electrical stimulation with scalp electrodes. We propose a quadrupole TMS coil configuration that can be electronically switched between active and sham modes. In active mode, the quadrupole coil has electric field characteristics similar to a conventional figure-8 coil. In sham mode, the quadrupole coil compared to the reverse-current sham figure-8 coil has 50% less electric field penetration depth, is 97% more focal, produces 35% less intense field in the brain, and induces scalp electric field characteristics closer to those of active TMS.
authors.affiliation: Department of Electrical Engineering, ColumbiaUniversity, New York, NY 10027, USA. zd2119@columbia.edu
authors.forename: Zhi-De
authors.initials: ZD
authors.lastname: Deng
authors.forename: Angel V
authors.initials: AV
authors.lastname: Peterchev
mesh_terms: D017076:Computer-Aided Design; D004582:Electronics, Medical / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D050781:Transcranial Magnetic Stimulation / Q000295:instrumentation*