Details

Autor(en) / Beteiligte

• Smith, J Evan
• Peterchev, Angel V

Titel

Electric field measurement of two commercial active/sham coils for transcranial magnetic stimulation

Ist Teil von

• Journal of neural engineering, 2018-10, Vol.15 (5), p.054001-054001

Ort / Verlag

England: IOP Publishing

Erscheinungsjahr

2018

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Objective. Sham TMS coils isolate the ancillary effects of their active counterparts but typically induce low-strength electric fields (E-fields) in the brain, which could be biologically active. We measured the E-fields induced by two pairs of commonly-used commercial active/sham coils. Approach. E-field distributions of the active and sham configurations of the Magstim 70 mm AFC and MagVenture Cool-B65 A/P coils were measured over a 7 cm-radius, hemispherical grid approximating the cortical surface. Peak E-field strength was recorded over a range of pulse amplitudes. Main results. The Magstim and MagVenture shams induce peak E-fields corresponding to 25.3% and 7.72% of their respective active values. The MagVenture sham has an E-field distribution shaped like its active counterpart. The Magstim sham induces nearly zero E-field under the coil's center, and its peak E-field forms a diffuse oval 3-7 cm from the center. Electrical scalp stimulation paired with the MagVenture sham is estimated to increase the sham E-field in the brain up to 10%. Significance. Different commercial shams induce different E-field strengths and distributions in the brain, which should be considered in interpreting outcomes of sham stimulation.