Neuroelectrics Frequently Asked Questions (FAQs)

From Neuroelectric's Wiki
Jump to: navigation, search


Is Enobio/Starstim a Dry Electrode system?

Yes, our devices can be used in dry mode for EEG recording (not for stimulation). We provide EEG dry electrode front-ends for the forehead and scalp. The two CMS/DRL electrodes require gel to increase CMRR and improve immunity to artifacts.

Is skin preparation critical when using Enobio/Starstim?

No, the system can be used without the usual skin preparation (scrubbing), although scrubbing will improve signal quality. Preparation for an EEG measurement is very simple, just fit the electrodes to the headband or cap, place it on the head and ensure a good contact between the electrodes and the skin. Cleaning the CMS/DRL application area and/or scrubbing a bit is recommended since they provide a common ground to the other electrodes.

How does the device communicate with the computer?

NIC2 is prepared to interact with Neuroelectrics devices using the wireless communication via Wi-Fi or Bluetooth and using the wired connection using the USB. Choose the type of connection compatible with your device.

For wireless connections with Windows systems, we provide a Bluetooth or Wi-Fi dongle with the system that has to be used only if your computer does not has Bluetooth/Wi-Fi integrated interface. Note that dongle is not compatible with Mac OS X system.

What does the provided NIC software do?

NIC software (Neuroelectrics Instrument Controller) is an application available for Windows and macOS that manages all aspects of device control, including data recording, data display, montage preparation, brain stimulation protocols and wireless communication between the device and the host computer. NIC was designed as a generic Neuroelectrics Instrument Controller, and it can work with both Enobio and Starstim class devices. It also offer interactivity with our devices using other softwares, including Matlab.

What operating systems are compatible with the Neuroelectrics software?

NIC is currently available for Windows (Vista and 7/8/10) and MAC OS X (> Snow Leopard).

The computer used to install NIC2 needs to have the following system requirements (minimum):

Processor: 1.6 GHz


Interface: USB, WiFi and/or Bluetooth® (3.0 or 2.1)

Screen resolution: 1280 x 768

How can I get the latest version of the NIC software?

The NIC software is constantly evolving. In order to be able to use the latest improvements of it, you can download the latest version from the Download Area on our website.

Can I connect my Starstim-Home device to NIC software?

Yes, from NIC v., your Starstim-Home device can be connected to NIC. Once the device is connected, you will be able to create protocols for your Home device, load custom waveforms into the device, and display the electric field generated in the brain in a 3D standardized model (Stim Preview).

What kind of data format is produced when doing an EEG recording using Enobio or Starstim??

In NIC there are several formats available for the EEG data (in NIC settings). From our simple, the .easy data format (a full 24 bit ASCII file of tab delimited columns) to the EDF+ standard (16 bit). You can save EEG, accelerometry (3 axis) and data markers using these formats. Check the Files and Formats section for more details.

If I want to have an EEG file in another format, how can I convert it?

The recorded files can be opened using NIC offline mode. In this mode, the files can be converted to the desired format (easy to edf/nedf, nedf to edf/easy and sdeeg to easy/nedf).

Can Enobio/Starstim data be accessed by other applications?

Yes, NIC provides two methods:

1) A TPC/IP socket in order to stream data to any TCP/IP capable application in real-time.

2) A Lab Streaming Layer which incorporates built-in network and synchronization capabilities that allow synchronization accuracy on 1 ms so it perfectly fits application like the one that detect ERPs signals.

 Please see Interacting with NIC section to be accessed by other applications.

Is it possible to send TTL triggers to mark Enobio/Starstim data?

Yes, we provide a TTL interface for this purpose. See the TTL User Manual and the TTL section.

What is the EEG resolution of our devices in µV?

The EEG signal resolution is 0.048 µV (dynamic range from -0.4 to 0.4 V). The smallest measurable signal is determined by the amplifier noise level (amplifier noise for low frequencies is 0.5 μV rms).

Using ERP-like paradigms where there are intense averagings, smaller signals than this can be detected.

What is the input noise?

The background EEG noise is 10-100 µV which is much higher than the Enobio/Starstim amplifier noise. Device electronic noise adds only a few percent to the total noise level.

What is the effective dynamic range in bits?

The dynamic range is 24 bit.

Does Enobio or Starstim provide a line noise filter?

The devices does not apply a line noise filter. However, the NIC software optionally uses a real-time 50/60 Hz line noise cancellation algorithm that preserves the original signal. This filter can optionally be applied by the user to the recorded data.

What is the function of the DRL/CMS reference?

The Driven Right Leg (DRL) and the Common Mode Sense (CMS) connections correspond to the electrical reference, or "ground", of the system. The CMS is the reference channel, compared to which all the EEG signals are measured. The DRL is responsible for bringing the potential of the subject as close as possible to the "zero" of the electrical system.

Is the contact of the DRL/CMS electrodes important?

Yes, the DRL/CMS contact is very important for high quality measurements, because it reduces the noise, mainly the 50/60Hz, and the drift of the EEG signals. For stimulation channels, the CMS/DRL contact is used to perform the impedance check of the electrodes. Please follow the procedures outlined in the User Manual to achieve best performance.

Which electrodes for DRL/CMS channels should be used with Enobio/Starstim?

Use our adhesive electrodes for the CMS and DRL positions (EEG electrical referencing) in our Enobio and Starstim systems. The Sticktrodes should be placed on the mastoid and as close as possible to each other. In particular, the Sticktrode for CMS should be placed slightly superiorly to the one for DRL. See the Troubleshooting / Problem Solving section for more info about the use of our Sticktrodes.

An alternative CMS/DRL electrode is represented by our EarClip. This dual electrode system is easily applied to the earlobe and requires use of conductive gel.

What is a differential reference?

Any electrode(s) can be used as a differential reference for the other channels; the choice is made entirely in software. When no reference is selected in our software, the signals are displayed with respect to the CMS electrode. The use of a differential referencing improves the CMRR of the measurements and therefore the signal quality. Such referencing can be done offline, once the data is recorded. Choosing a reference in NIC has an effect only on visualization: the system always records raw data(referenced to the CMS electrode).

What is the bandwidth of our devices?

EEG functionality: our devices allow for measurements of signals from 0 to 125Hz (DC coupled).

Stimulation functionality: our devices allow to generate signals with a frequency range from 0 to 250 Hz (tACS) and from 0 to 500 Hz (tRNS).

Does Enobio/Starstim have adjustable filters?

Yes, the NIC user interface allows the user to select a digital filter implemented in software. However, such filters are only used for visualization of the data and cannot be applied to the recorded data. Data are always recorded in the full bandwidth.

What are the sampling rate of our devices?

EEG functionality: the sampling rate is 500 Samples Per Second (SPS).

Stimulation functionality: the sampling rate is 1000 SPS.

What type of SD cards are recommended?

For optimal performance, fast micro SDHC (Micro Secure Digital High-Capacity) cards are recommended (UHS-I or higher, Class 10). Examples (Jan 2014) include Sandisk 8GB microSDHC Ultra (UHS-I) or Samsung MicroSDHC Plus, with writing speeds over 30 MB/s. For devices with 8 channels, an 8GB size card will be able to hold very long recordings (>10 hrs).

Every minute is 1.89 MB

I was able to connect my device with NIC but suddenly I can not connect it anymore. What can I do?

If your device is paired with the computer but does not connect with NIC, the best option is to remove the device from the Bluetooth devices list.

 Blutooth devices or bluetooth configuration.png     Removedevice.png

Once removed, switch OFF/ON the device and go to the Bluetooth settings again.

In the Bluetooth devices list, it will appear again the device to pair. If you select 'Pair', you will be able to connect again with your device. If a password is required to connect to the device, type 9845.


Finally, open NIC and try to connect again the device.

The signal quality indicator is red. What should I do?

In NIC2, the EEG signal quality is measured for each electrode in real time. Different factors may influence the signal quality, such as the type of EEG electrodes and the CMS reference channel.

Wait few minutes for the signal to stabilize. If the quality indicator is yellow or red in all the channels, it may be related to the reference.

If the quality indicator is red only on one channel, it may be related to a bad contact between the corresponding electrode and the scalp.

Note that the quality indicator is meant to be used as a guide, it does not need to be taken strictly. Visual inspection of the signal is equally important, which means that if the signal looks good and the indicator becomes red at some point, there is no need to immediately stop recording.

How should I clean the neoprene cap?

After each use, the neoprene cap or the neoprene band should be cleaned and disinfected. Use warm tap water to rinse the gel and some ivory soap to clean the cap. Dry the cap consciously using paper towel. Spray the cap with disinfectant and let sit for 10 minutes. Rinse cap thoroughly. Hang up the cap to dry.

How many NG Pistim electrodes can I fill with one bottle of Signa gel?

- With a 250g bottle of Signa gel, you can fill 13 curved syringes of gel.

- A 12ml-curved syringe can be used for 7 NG Pistim electrodes.

So, with one bottle Signa gel (250g), you can fill 91 NG Pistim electrodes.

Note that this is the ideal scenario, but these quantities may vary in case you need to add more gel to improve the contact between the electrode and the scalp.

Is it important to clean the electrodes after each use?

Electrodes' durability depends on the maintenance. It is very important to remove all the gel from the electrodes and from the cap after each use. After washing the electrodes with tap water and use a tissue to complete the cleaning.

What can damage my electrodes and reduce their durability?

Sunlight exposure or contact with metals might damage the electrodes. Avoid the direct sunlight exposure and the contact with metals when the electrode is not being used.

It is important to highlight that the NG Pistim and NG Geltrode electrodes need to be stored avoiding the direct contact between the pellet of one electrode and the metal pin of other electrode.

What is the lifetime of my electrodes?

The number of uses or hours of recording using our EEG electrodes depends on how are they cleaned or stored. Electrode degradation can be suspected when the electrodes' signals are too noisy. If your electrodes signals are becoming noisy, replace them with new ones.

The lifetime of Ag/AgCl stimulation "Pistim depends on their use. The electrodes degrade while passing current, but the process reverses if the direction of currents is reversed. For this reason, it is advisable to swap anode and cathode in tDCS protocols to increase electrode lifetime.

Please see the | Electrode User Manual for a detailed description of our electrodes.

What do I need to consider when creating a stimulation protocol?

Any protocol needs to be in accordance with the following rules:

- The maximum current per channel is 2mA.

- The absolute sum of injected currents cannot be greater than 4mA (sum of all channels).

- The sum of injected currents must be 0mA at any time (sum of all channels current taking into account the polarity. Satisfy Kirchhoff's Laws).

All of these rules are checked if they are accomplished by the software when finishing and saving the protocol.

What’s the difference between the standard montage and the user-defined montage?

For 20-/32-channel Starstim devices, the user can choose between Standard and User-defined Montage. The former option locks the positions to the predefined montage of the standard system 10-20, whilst the latter option allows any of the 76 scalp map positions to be assigned to the channels of the device, taking into account the channel number assigned in NIC during the setup.