Full FAQ List by Topic
PowerMAG TMS (6)
Maybe. There is no way the EEG system can harm the TMS system, but there are some TMS systems that are essentially useless with some EEG systems. You need a a suitable combination of features in each to be successful at all in using TMS with EEG.
- Coils designed specifically for use with EEG will have a cable that exits the coil tangential to the head surface so that the coil does not pass close by EEG electrodes and cables.
- A coil to be used with EEG should be passively cooled, since active cooling by means of a fan will induce electromagnetic interference in the EEG.
- The TMS recharge mechanism should be designed to avoid inducing electromagnetic artifacts in the EEG.
- The TMS system should be shielded so that no more than 3 milligauss of electromagnetic interference from the TMS system’s power supply reaches the electrodes and cables.
- The TMS system should be able to produce a TMS pulse in response to an input trigger with a low and predictable latency. Long, but especially unpredictable latency in responding to an input trigger will result in TMS artifacts that are difficult to impossible to remove from the EEG.
Aside from attributes of the TMS system, there are also important considerations regarding the EEG system in this relationship. See the other FAQ entry on that topic.
No. There are a few special attributes that are required and others that are desirable.
- Inputs should be protected so that they are not damaged by the TMS pulse
- Frequency response on all channels should be from DC on the low end, since AC coupled inputs will “ring” when presented with a large voltage transient like the TMS artifact
- Electrodes should have a low-profile so that the TMS coil can be placed as near the head as possible, maximizing penetration depth and current delivery
- It is important for the EEG system to be able to trigger the TMS system at precisely the same phase with respect to the EEG samples each time a stimulus is delivered. This will improve the performance of artifact removal algorithms
Aside from attributes of the EEG system, there are also important considerations regarding the TMS system in this relationship. See the other FAQ entry on that topic.
You may perform a wide variety of protocols using the PowerMAG system; ppTMS, rTMS, TBS, and even Quattro pulse. Please refer to the following chart to determine which platform is most appropriate for your research.
|Stimulators||PowerMAG lab 30||PowerMAG lab 100||PowerMAG EEG 30||PowerMAG EEG 100||PowerMAG ppTMS||PowerMAG QPS|
|Characteristic||Economic research||Basic research with TBS||EEG research||Advanced real-time EEG||All in one||qTBS stimulation|
|Stimulation frequency (Hz)||30||100||30||100||100||100 (666 in bursts)|
|Long interval ppTMS||Yes||Yes||Yes||Yes|
|Short interval ppTMS||Yes|
|Coil current invertable||Yes||Yes||Yes||Yes||Yes||Yes|
The coils used with the PowerMAG system are in fact passively cooled, they utilize quality copper windings with excellent heat dispersion properties. The coils are then placed within a wax like medium that further enhances heat dissipation, as the coil heats up the internal medium changes to a liquid state effectively “absorbing” much of the heat. This is often desired over coils that require additional components for cooling (e.g. fans, pumps, and plumbing), and are considered more robust from an engineering perspective. Additionally there is no maintenance required for our passively cooled coils, nor is there any pre-defined factory set limit to the life of the coil in terms of number of pulses, nor age.
This really comes down to the properties of the coil utilized. The two main style of stim coils used within the TMS field are figure 8 and round, with figure 8 often being preferred for focal targeting. Typically with the figure 8 coil you would get greatest stimulation at a depth of roughly 2- 2.5cm, with a round style you may achieve a bit more penetration ~2.5-3cm.
Excellent question! As of currently the PowerMAG is strictly for research purposes, meaning there is no FDA approval on the device, thus it may not be used for the diagnosis or treatment of any pathology. Clinical research is still possible, however must follow the strict adherence to the current guidelines imposed. Chances are if you are having to file for an IRB, then you can use the PowerMAG system for your research.