TMS transcranial magnetic stimulation
Transcranial magnetic stimulation (TMS) is a noninvasive method of studying brain functions and interconnections—it causes hyperpolarization or depolarization of neurons in specific or general parts of the brain. For TMS and repetitive TMS (rTMS) studies, BIOPAC has wireless and wired solutions for EEG, ERS, and EMG. Transcranial magnetic stimulation (TMS) can be used in conjunction with fMRI and transcranial direct current stimulation (tDCS) or transcranial alternating current stimulation (tACS).
Always use carbon leads for any electrode lead that will get close to the TMS field. and always use non-metallic carbon electrodes if concurrent EEG data is required. EL-CHECK Impedance Checker is recommended for all use cases to verify impedance levels before recording so placement or connections can be adjusted if necessary to optimize signal quality.
- For EEG on the scalp, use EEG100D or ERS100D, combined with carbon leads and electrodes: EEG100D/ERS100D + BN-ADAPT-TP3 + LEAD108C x3 + EL508
- To use TMS to stimulate and then look at the EEG (rather than looking at the EEG at the time of stimulation): use EEG100D Smart Amp with short leads BN-EL15-LEAD2 or BN-EL15-LEAD3 and regular, non-carbon electrodes and twist the EEG leads so that the induced current (via leads) is low; in this scenario, any artifacts in the EEG are irrelevant.
- For EMG or fEMG, use EMG100D + BN-EL15/30/45-LEAD3 + EL503/EL504/EL513 + abrade with ELPREP and/or ELPAD
- Wireless options include BioNomadix series BN-EEG2 or BN-EMG2 transmitters with matched receiver or logger—always place the BioNomadix transmitter, which has some ferrous parts, at least one foot away from the TMS magnetic stimulator.
- Older C-series wired amplifiers can be used with module extension cable and carbon leads: EEG100C/ERS100C/EMG100C + MEC110C + LEAD108C (30 cm) + EL508/EL509.
The STMISOLA will support arbitrarily long, constant, non-varying, direct output currents, so long as the associated voltage compliance is 100 VDC or less. The level is adjusted by holding a stable voltage to the control voltage input of the STMISOLA. This control voltage can be set in AcqKnowledge, to be output to STMISOLA via MP160/150 analog output.
BIOPAC is unaware of safety concerns related to this procedure, however it is our understanding that TMS is an investigative protocol. As a safety precaution, please verify output currents prior to any subject measurements. There are no known measurement impacts when performing TMS with other BIOPAC equipment.