Difference between revisions of "Tips & Tricks"

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(The impedance test)
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=Tips for EEG recording using Enobio or StarStim =
 
=Tips for EEG recording using Enobio or StarStim =
In this page we provide some tips and tricks to work with our systems.  Here are some useful resources you should also check this Jove video on the combination of EEG and tDCS as well as tutorial videos:
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In this page we provide some tips and tricks to work with our systems.  Here are some useful resources you should also check:
  
- [http://www.jove.com/video/50426/simultaneous-eeg-monitoring-during-transcranial-direct-current '''StarStim tCS EEG recording (Jove)''']  
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- [http://www.jove.com/video/50426/simultaneous-eeg-monitoring-during-transcranial-direct-current | '''StarStim tCS EEG recording (Jove)''']  
  
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- [http://www.youtube.com/watch?v=JdcG1Qdq4h8 | '''A short introduction to NIC v1.2''']
  
{{#ev:youtube| JdcG1Qdq4h8|500|center|An introduction to NIC}}
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- [http://www.youtube.com/watch?v=I5uU20ut8Fk | '''Stimulation configuration with NIC v1.2''']
 
 
{{#ev:youtube|I5uU20ut8Fk|500|center|Configuration of NIC for stimulation: from simple to advanced}}
 
 
 
 
 
== Plan your session well before starting ==
 
You should have a clear plan covering all the details in your recording session.  Prepare to be patient. Setting up always takes a bit longer than expected, and when carrying out experiments ... the third time's the charm!
 
 
 
Before starting keep your device charged. It is best to ensure you have more than 50% charge before you start.
 
 
 
Where do you want to place the electrodes? For how long do you want to record? Do you have a good naming scheme for your EEG files? What data formats do you want to save? Do you need accelerometry data? Do you want a line filter applied to the data (if so 50 or 60 Hz)?
 
 
 
Do you have an '''electrode referencing''' scheme planned ahead? You should include in your montage construct a solution for data referencing. With our systems, data will be recorded referenced to the device electrical ground (the CMS electrode), but for data analysis you should always reference the data to an electrode or to the electrode average. See as an example this [http://www.nitrc.org/forum/forum.php?thread_id=3094&forum_id=2 | link ] of an open discussion for more information on referencing.
 
  
 
== Place carefully the CMS and DRL electrodes ==
 
== Place carefully the CMS and DRL electrodes ==
 
[[File:CMSDRL.jpg|250px|thumb|left|]]
 
[[File:CMSDRL.jpg|250px|thumb|left|]]
These two electrodes should go over the left or right mastoid (best to always stick to one side).
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These two electrodes have to be placed over the left or right mastoid (preferably on the same side). First, clean up the mastoid area where you are going to attach the CMS/DRL electrodes. You can use a paper napkin with some water or alcohol. Removing the grease and drying the skin will help you to get a good signal.  
First clean up the mastoid area where you are going to attach the DRL/CMS electrodes (using Sticktrode adhesive electrodes).  
 
You can use a paper napkin with some water or alcohol. Removing grease and dry skin will help you get good signal.
 
  
Stick the DRL/CMS electrodes close to each other, with the DRL on the bottom.
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Place the Sticktrode adhesive electrodes close to each other with the DRL on the bottom, as shown in the figure. Ensure that the two electrodes are not touching each other. The CMS electrode should be on top of the mastoid bone to avoid contamination from blood vessels (ECG like signals).
These two Sticktrode electrodes should be '''close to each other but not touch.''' The CMS electrode should be on top and squarely on top of the mastoid bone. This will avoid contamination from blood vessels (ECG like signals).
 
  
== Avoid loose wires ==
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== About EEG signal quality measures in NIC ==
Try to have a tidy setup with few loose wires. Loose wires are more prone to creating noise from movement.
 
  
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In NIC2.0 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.
  
== About EEG signal quality measures in NIC ==
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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.  
NIC, EEG signal quality measures for each electrode are provided in real time.  
 
 
 
If all the channels are in yellow or red zone, you may have an issue with the CMS/DRL electrodes (they create the ground for measurements, so if they are misplaced all the signals will be affected).
 
  
If an electrode is misbehaving, check that it has a good contact and, if possible, add more gel (you can reach the site from another hole in the cap).
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If the quality indicator is red only in one channel, it may be related to a bad contact between the corresponding electrode and the scalp.  
  
Give a few minutes at the start for signals (electrochemistry) to stabilize.
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Note that the quality indicator is meant to be used as a guidance, 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.
  
 
= Tips for great Stimulation sessions using StarStim =
 
= Tips for great Stimulation sessions using StarStim =
  
See the section above on placing well the DRL/CMS electrodes. '''They are also important for stimulation''', as they are used for our impedance check (as well as EEG recording, if any).
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See the section above for a proper placement of the DRL/CMS electrodes. '''These electrodes are also important for stimulation''', as they are used to perform the impedance check.  
 
 
== Using Sponge electrodes ==
 
 
 
Sponge electrodes are easy to use. You can place them on the cap and wet them (about 2-4 cubic cm of saline solution will do) prior placing the cap on the subject's head.
 
 
 
If you have impedance issues, rewet them from a side hole using a syringe. Be careful not to wet the cap.
 
  
== Using Ag/AgCl Pi electrodes ==
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== How to improve contact impedance ==
Pi  electrodes are also easy to use. You can place them on the cap and gel them (fill the electrode hole space and then some more)  prior placing the cap on the subject's head.
 
  
If you have impedance issues, regel them from the electrode hole or a side hole using a syringe.  
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The impedance of the stimulation channels can be measured by NIC. This feature is available for StarStim devices but not for Enobio devices. The impedance bar appears below the icons of the stimulation channels and its color depends on the obtained value:
  
== The impedance test ==
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'''green:''' [0 - 10] kOhm
  
You should carry out an impedance test before launching a stimulation (at least for the first session if you have several on a row with the same subject). If impedance is too high (red values) for some electrode you can follow these steps:
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'''orange:''' [10 - 15] kOhm
  
- Check cabling connections and recheck impedance and recheck impedance
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'''red:''' [10 - 15] kOhm
  
- move the hair to ensure the contact between the electrode and the scalp
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We always recommend running the impedance check before launching a stimulation protocol. If the impedance is too high (red tab), it is probably related to the setup. Below are some suggestions to follow in case of high impedances:
  
- make sure the hair is clean and free of sprays, oils, cream and lotions. Shampoo your hair and rinse with clear water the
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- move the hair to ensure the contact between the electrode and the scalp
evening before or the morning of the test.
 
Avoid hair conditioner or oil
 
  
- add more gel/saline solution (rewet or regel) to the electrodes and check again
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- make sure the hair is clean and free of sprays, oils, cream and lotions. Shampoo your hair and rinse with clear water the evening before or the morning of the test. Avoid hair conditioner or oil
  
- check that the DRL/CMS electrodes are correctly placed
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- add more gel/saline solution to the electrodes
  
- ensure that you have a reasonable battery charge (>20%)
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- check that the DRL/CMS electrodes are correctly placed
  
- impedance depends on skin type and can vary quite a bit across individuals
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- ensure that you have a reasonable battery charge (>20%)
  
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Note that impedance depends on skin type and can vary quite a bit across individuals.
  
For safety, impedance is also checked by NIC while stimulation is ongoing. If the impedance is too high, the stimulation session will self-abort.
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For safety reasons, the impedance is measured by NIC while stimulation is ongoing. If the impedance is too high, the stimulation session will self-abort.
  
 
= Everything about electrodes for EEG and stimulation =
 
= Everything about electrodes for EEG and stimulation =
 
[[File:electrodes1.png|200px|thumb|left|]]
 
[[File:electrodes1.png|200px|thumb|left|]]
  
Please see the [http://www.neuroelectrics.com/download/NE_UM_Part02_Electrode.pdf | '''Electrode User Manual'''] for a description of our electrodes.
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Please see the [http://www.neuroelectrics.com/download/NE_UM_P2_Electrodes.pdf | '''Electrode User Manual'''] for a description of our electrodes.
  
 
== Caring for EEG electrodes ==
 
== Caring for EEG electrodes ==

Latest revision as of 11:33, 12 June 2017

Tips for EEG recording using Enobio or StarStim

In this page we provide some tips and tricks to work with our systems. Here are some useful resources you should also check:

- | StarStim tCS EEG recording (Jove)

- | A short introduction to NIC v1.2

- | Stimulation configuration with NIC v1.2

Place carefully the CMS and DRL electrodes

CMSDRL.jpg

These two electrodes have to be placed over the left or right mastoid (preferably on the same side). First, clean up the mastoid area where you are going to attach the CMS/DRL electrodes. You can use a paper napkin with some water or alcohol. Removing the grease and drying the skin will help you to get a good signal.

Place the Sticktrode adhesive electrodes close to each other with the DRL on the bottom, as shown in the figure. Ensure that the two electrodes are not touching each other. The CMS electrode should be on top of the mastoid bone to avoid contamination from blood vessels (ECG like signals).

About EEG signal quality measures in NIC

In NIC2.0 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 in 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 guidance, 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.

Tips for great Stimulation sessions using StarStim

See the section above for a proper placement of the DRL/CMS electrodes. These electrodes are also important for stimulation, as they are used to perform the impedance check.

How to improve contact impedance

The impedance of the stimulation channels can be measured by NIC. This feature is available for StarStim devices but not for Enobio devices. The impedance bar appears below the icons of the stimulation channels and its color depends on the obtained value:

green: [0 - 10] kOhm

orange: [10 - 15] kOhm

red: [10 - 15] kOhm

We always recommend running the impedance check before launching a stimulation protocol. If the impedance is too high (red tab), it is probably related to the setup. Below are some suggestions to follow in case of high impedances:

- move the hair to ensure the contact between the electrode and the scalp

- make sure the hair is clean and free of sprays, oils, cream and lotions. Shampoo your hair and rinse with clear water the evening before or the morning of the test. Avoid hair conditioner or oil

- add more gel/saline solution to the electrodes

- check that the DRL/CMS electrodes are correctly placed

- ensure that you have a reasonable battery charge (>20%)

Note that impedance depends on skin type and can vary quite a bit across individuals.

For safety reasons, the impedance is measured by NIC while stimulation is ongoing. If the impedance is too high, the stimulation session will self-abort.

Everything about electrodes for EEG and stimulation

Electrodes1.png

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

Caring for EEG electrodes

Electrodes2.png

It's very important to remove all the gel from the electrodes (and cap!) carefully after a recording session using gel. You can do this with water.

Sunlight exposure or contact with metals might damage the electrodes.

With our wet electrodes some discoloration may occur after a few uses. It is normal and does not affect data quality.

Caring for stimulation electrodes

Electrodes3.png

It's important to rinse stimulation electrodes (sponges and Ag/AgCl alike) with water in order to remove the salts that might remain after drying.

It is also recommended to dry the metal part to avoid salt on the connectors.

In case there salt accumulating at the metallic part, it can be washed with some vinegar to remove it.

Electrode lifetime

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 "Pi"-electrodes depends on their use. The electrodes degrade while passing current, but the process reverses if the direction of currents are reversed. For this reason, it is advisable to swap anode and cathode in tDCS protocols to increase electrode lifetime. Degraded electrodes will produce degraded, noisy EEG, and may give higher impedance values on Impedance Check. A rule of thumb is that a pair of electrodes used for tDCS without swapping Anode and Cathode should last for about 8 h worth of stimulation (about 24 20 minute stimulation sessions). Swapping electrodes will increase their lifetime. The lifetime for these electrodes with tACS or tRNS will be much longer.

The lifetime of sponge electrodes is very long.

Cable instructions

After each use it is important to disconnect the cables from the electrodes in order to avoid contact with both metals (metal of the electrodes and metal of the cable). If it is not disconnected the cables and also the electrodes can be damaged.

Neoprene cap cleaning and disinfecting instructions

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.