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 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 throw away.

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 is the deciding factor for children, for patient populations, and for any protocol with repeated sessions where subject dropout is what costs you the dataset. The trade is higher impedance and more sensitivity to movement artefact.

g.Nautilus Research takes g.SCARABEO gel electrodes or g.SAHARA hybrid electrodes that run dry or wet, at 8, 16, 32 or 64 channels. Same headset either way.

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. On g.Nautilus the amplifier sits on the cap for exactly that reason.

Tethered amplifiers still win on channel count and on invasive work. g.HIamp runs 256 channels per device, scales to 1,024 synchronised channels, and is FDA cleared and CE certified for invasive and non invasive recording.

If your paradigm is a seated screen task, this decision is smaller than the vendors make it sound.

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:

1. 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.
2. What the measured jitter is, not the specified jitter.
3. Whether your presentation software is supported. E-Prime, PsychoPy and Psychtoolbox all behave differently.

g.Recorder reads TTL inputs directly and supports g.USBamp, g.HIamp and g.Nautilus. That is why TMS EEG works with it. The timing of the TMS pulse comes in on the TTL inputs of the amplifier and is stored alongside the EEG, so the ERPs can be averaged afterwards. g.Recorder also runs its own paradigm presenter, which takes E-Prime and Presentation out of the timing chain entirely.

Combining EEG with other measures

EEG and eye tracking is the combination we install most often, 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 from one headset.

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

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

Which g.tec system

g.Nautilus Research – 8, 16, 32 or 64 channels, wireless, gel or hybrid dry and wet, research use only
g.Nautilus PRO Flexible – wireless, configurable channel count, the clinical version of the same platform
g.USBamp Research – tethered biosignal amplifier and acquisition system
g.HIamp – 256 channels per device, tethered, invasive and non invasive

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.

The full specification comparison sits on our EEG systems page.

Send me the paradigm you plan to run and the number of subjects, and I will tell you which of these four I would put in your lab and which I would leave out. If 32 channels is enough for what you are running, that is what you will hear from me, even though the 64 costs more. What do you think?