Choosing an EEG system for your lab

Most labs that contact us about EEG have already decided they want EEG. The harder question is which one, and it breaks into four parts: how many channels, dry or wet electrodes, what the amplifier has to synchronise with, and who repairs it when it fails in Israel.

NBT has supplied research instrumentation in Israel since 1992 and is the exclusive distributor of g.tec medical engineering here. This page is the advice we give on the phone.

How many channels

8 to 16 channels covers BCI work built on motor imagery or SSVEP, and covers teaching labs.

32 channels is the practical floor for ERP research. Below that you have no room to reject a bad channel and still keep your montage.

64 channels is where source localisation starts to be worth attempting.

128 and above belongs to labs doing dense source reconstruction. The cost there is not only the amplifier. Preparation time per subject rises with every electrode, and so does the number of sessions you discard.

Our opinion, and it is ours: buy the channel count your analysis needs, not the one your grant allows. A 64 channel system that takes 45 minutes to prepare gets used less than a 32 channel system that takes 15. We have watched this happen in Israeli labs more than once.

Dry or wet electrodes

Gel electrodes give lower impedance and cleaner low frequency data. If you are recording ERPs, slow cortical potentials, or anything below 1 Hz, gel is the safe choice.

Dry electrodes cut preparation to a few minutes and remove the hair washing problem. That matters for children, for patient populations, and for any protocol with repeated sessions where subject dropout is the real risk to your dataset. The trade is higher impedance and more sensitivity to movement artefact.

g.Nautilus is available in a gel version and in a hybrid dry and wet version, with 8, 16, 32 or 64 EEG channels.

Wireless or tethered

Wireless removes cable movement, which is itself an artefact source, and it is the only option if the subject walks, cycles, or reaches. g.Nautilus attaches the amplifier to the cap for exactly that reason.

Tethered amplifiers still win on channel count and on invasive work. g.HIamp runs 256 channels and is FDA cleared and CE approved for invasive and non invasive recording.

If your paradigm is a seated screen task, this decision matters less than the vendors suggest.

Triggers and synchronisation

This is where first EEG purchases go wrong, and it is the question almost nobody asks before signing.

Before you buy, confirm three things:

• How the stimulus computer sends the trigger. Parallel port, TTL input, LSL, or a software marker with unknown latency. The last one is not acceptable for ERP work.
• What the measured jitter is, not the specified jitter.
• Whether your presentation software is supported. E-Prime, PsychoPy and Psychtoolbox all behave differently.

g.Recorder reads TTL inputs directly and supports all g.tec acquisition devices, which is why TMS EEG work is possible with it: the exact timing of the TMS pulse is recorded alongside the EEG.

Combining EEG with other measures

EEG and eye tracking is the most common combination we install, usually for ERP work where you need to know where the subject was looking when the component appeared.

EEG and fNIRS gives you electrical and haemodynamic signals from the same session. g.Nautilus Research works with g.SENSOR fNIRS for simultaneous recording.

EEG inside the MRI is a different purchase with different safety requirements. Ask us before you specify it.

EEG with TMS requires an amplifier that recovers fast enough from the pulse. Not every amplifier does.

Buying EEG in Israel

You can buy an EEG system directly from a manufacturer in Europe or the United States. Labs do it, and for a single wearable headset it can work.

What you give up is the part that costs you time later. Customs and import handling. A calibration or repair that means shipping the amplifier abroad and waiting. Application support in your time zone when a montage will not converge two days before a conference deadline.

NBT installs, trains, and supports in Israel, Sunday to Thursday, on site when needed.