EEG
On This Page
Safety Certification and Training
1.1 How to get certified
The first step to booking EEG suite time at the CCN is certification and training. The certification for use of EEG equipment follows a protocol analogous to that for MRI certification (see MRI section 1.1). It can be accessed through the same Bruinlearn link and is available as its own module (EEG certification), which includes study materials and online test, followed by a walkthrough needed for operation of the EGI equipment.
Project Management
2.1 Setting up a project.
Scheduling EEG time can be done using the same platform as is used for the MRI suite (https://www.sistat.ucla.edu/ccnsas/login.asp). You will need to have an active project to access the scanner and book time (see MRI section 2.1-2.3).
2.2 Costs
EEG Data Collection $100/hr
EEG (with fMRI) Data Collection $75/hr
Personnel Policies
The same policies apply to the EEG suite as to the MRI suite. Please be familiar with sections 3.1-3.7 of the MRI guide.
Scheduling Policies
The same policies apply to the EEG suite as to the MRI suite. Please be familiar with sections 4.1-4.2 of the MRI guide.
Facilities & Equipment
The EEG Suite contains two fully shielded EEG suites and a prep room. There is a SiStat booking system to reserve the Staglin EEG Suite. Request access to SiStat by emailing CCN support (ccnsupport@g.ucla.edu). When you are ready to collect EEG data, make a reservation on SiStat ahead of time.
5.1 The Left EEG Suite:
EGI Net Amps 400
-MR-safe EGI Net Amps 400 - EGI HydroCel EEG Nets - S/M/L of MR and non-MR compatible versions
5.2 The Right EEG Suite:
Bio-Semi 64 channel EEG system using active electrodes
EEG Procedures
6.1 Default Setup
The default set up includes:
monitor
keyboard
speakers
intercom/ webcam
response box
If you are not using some of the items above, you may move them aside, but do not disconnect them.
The connections for the monitor, keyboard, and speakers are bound together and hung on the side of the desk. Plug these directly into your stimulus computer.
For the addition of other peripherals, please contact the suite administrators.
Procedure for routine net tests: https://www.egi.com/images/stories/manuals/Printed%20IFUs%20with%20New%20Notified%20Body/HC_GSN_RM_sponged_appl_uins_8403481-53_20181210.pdf
6.2 Equipment and Supplies
Most of the supplies needed for EEG testing is located in the EEG net room in the wooden cabinet by the sink. If you open the left cabinet, on the main top shelf, most of the supplies you will need for testing will be located in the plastic bin labeled with EEG supplies. You will find the following in that bin:
scissors
red wax pencil
tape measure
spandages
disposable EEG/MR electrodes
Johnson’s baby shampoo, EEG solution salt, extra electrodes, the EGI net manual, and EGI net boxes along with their respective measuring spoons are usually located on top of the cabinet by the sink. The electrodes and the net boxes are in the cardboard boxes on top of the cabinet.
In the EEG Suite’s left testing room, you will find remaining supplies in the cabinets to the left of the table with the computer monitor and the EGI amp. The cabinet shelves are labeled with these items:
latex gloves
disinfectant
pipettes
medical tape
EEG solution salt
If you see that something has run out, check the following places to see if extras are stored:
the wooden cabinet by the sink the EEG net room (Johnson’s baby shampoo and spandages may be hiding in the shelf below the plastic bins, in the bottom drawers, or on top of the cabinet)
the cabinets in the EEG suite (currently, there are MANY boxes in the right-most cabinet in the testing room and some on the top shelf of - the cabinet where the Stimulus computer lives).
NOTE: If something has completely run out, there is an emergency supply located in the shop, but please ask Agatha, Sam, or Cameron for these supplies. BUT ONLY FOR EMERGENCIES.
Where to order EEG supplies:
We have had success ordering supplies from the following places. The ones ordered from online sites accept purchase orders:
Pipettes (5.8mL, non-sterile) - Fisher Scientific
MT Spandages (MT07, 7-inch spandage, 25 yards) - Vitality Medical MT Spandage
Johnson & Johnson Baby Shampoo - please send a purchase request to the CCN Administrator
EGI Potassium Chloride (KCl) (2Lb) - E-mail: sales@magstimegi.com
Control III Disinfectant (16 oz. bottle) - E-mail: control3@earthlink.net
GSR Electrodes (EL509, 100 electrodes/box) - Biopac Systems, Inc.
Self-Adhesive Bandage (Item 2082, 2-inch x 5 yards, latex-free) - Vitality Medical Self-Adhesive Wrap
6.3 EEG Net Prep and Application
All the supplies you will need can be found in/on the wooden cabinet in the prep room. Inside the cabinet, there is a box marked “EEG Prep Supply” which contains smaller items such as the measuring tape, the red pencil, and scissors.
Preparing the Electrolyte Solution
In the prep room, grab an empty plastic bucket and fill it with warm water to the 2 quart line.
Mix in 1 scoop of the potassium chloride and 1 spoonful of shampoo.
Each has its own measuring spoon which you should find in the potassium chloride box and next to the shampoo. The spoons are also conveniently named “potassium chloride” and “shampoo” on their handles. You can use the “shampoo” spoon to stir the solution until the ingredients have fully dissolved.
Fitting the Right Net
Measure the circumference of the largest part of your subject’s head in centimeters (usually sits right above the eyes).
Match this measurement to the range displayed on the plug of one of the nets.
Measuring and Marking the Vertex
To find the point where the Cz electrode (REF) should sit, you’ll take 2 perpendicular measurements with the red pencil in hand:
Measure from behind the top of one ear to the same point behind the other ear (like where a headband would sit). Draw a short perpendicular line at the midpoint of this distance.
For the perpendicular nasion/inion measurement, ask the subject to hold the starting end of the measuring tape between his or her eyes and then draw the tape back to just below the bump at the back of the head. Draw a short perpendicular line at the midpoint of this distance.
Referencing your 2 marks, draw a cross at the intersection to find the vertex.
Soaking the Net
Wrap the towel around the plug of the previously determined net. This connection must always remain DRY!
Turn the net inside out with the sponges facing out, make sure all clasps are fully loosened, and immerse the net in the electrolyte solution so that all sensors are fully submerged. It is easiest to place the wrapped plug on a chair and then have the bucket of solution on the floor or in the sink to ensure the plug doesn’t come near water.
Let the net soak for 5-10 minutes. If the net is soaked for too long, it may take up too much solution which can cause bridging between sensors so be mindful of the time!
Applying the Net
Have the subject sit in a chair facing you. Place the bucket with the soaking net on the floor in front of them and ask them to hold the wrapped plug in their lap. Place a towel over his or her shoulders to catch drips.
Turn the net back the right way (sponges in) and gently shake excess electrolyte solution from the net.
Place both hands inside the net with your fingers spread out to stretch the net. The elastics holding the net together are very delicate so careful not to overstretch the net!
Instruct your subject to close his or her eyes.
Begin to bring the stretched net straight down over your subject’s head. Align the center front electrode between their eyes and then slightly rotate your hands back to stretch the net back and down the back of the head.
Tighten the sides and then center clasps. At this point you may allow your subject to open his or her eyes and dry any drips as needed.
To align the cap over the earholes correctly and to match REF to the vertex, plant all five fingers in the net and then move as needed, wiggling the net a bit to allow the sensors to find their way through the hair to the scalp. Once again, the net is very delicate! Moving with the whole hand, fingers planted in various positions will more gently and efficiently shift/move the net for you.
Plugging the Net into the EGI Amplifier
Plug the net into the amp by first positioning the plug in the amp and then turning the knob from down to up. The cord of the net will be to the RIGHT of the plug. The plug will draw itself into the correct position. Do not force the plug into the amp. The pins in the connector are very fragile.
Helpful Tips
You will want to bring the bucket of electrolyte solution with you into the testing suite as you will need it to lower impedance. However, place it under a chair or in a corner where it is far from the equipment on the floor and will not be tripped on and spilled! It is also suggested that you leave the towel over your subject’s shoulders for the entire task to catch any drips that may occur later on.
6.4 Impedance Check
Mirror EGI Display
Checking and lowering impedance requires a lot of back and forth between the desktop monitor and your subject in the testing suite. To make your life a little easier, plug the suite monitor DVI cable into the desktop cable, labeled Mirror EGI. This way you will be able to view the impedances of the electrode sensors as you are fixing them.
If this doesn’t work immediately, check System Preferences –> Display and turn on mirroring.
Just be sure to switch back to the testing suit monitor DVI when you are done!
Checking Impedance
Once the net is plugged in and NetStation is open, check that the amp is “On” in the top right corner. You can confirm this in the Dense Waveform Display panel to see that you are receiving real-time signal.
Among the NetStation panels, find the Impedance panel, which can also be located in the Panels drop down menu.
Click Measure Impedance. (It will take about a minute to load.)
You will see some (hopefully most) electrodes green, and some electrodes red. The electrode sensors marked red need a little help to gain better connection.
Lowering Impedance
To lower impedance, we’re going to add more electrolyte solution to the electrodes marked red. You will need:
the electrolyte solution you prepared for soaking the net
a plastic pipette (located in a box in the cabinet on the right in the testing suite)
Instructions
Noting the numbers of the red electrodes in the Impedance panel, locate these electrodes on your subject’s net.
With a pipette full of electrolyte solution in hand, one by one, lift (and slightly twist) an electrode to pipette a few drops of solution into the sponge of the electrode. Wiggle the electrode back into place through the hair for better contact with the scalp. We are really aiming for the sponge of the electrode to be in contact with the skin of the scalp rather than sitting on the hair. Apart from creating a better channel between the electrode and scalp via solution, this direct contact with the skin is key to gaining better connection.
Repeat this process until you are satisfied with the number of green electrodes. This process may take 5-10 minutes. Be mindful that as time passes, solution is absorbed into the hair, electrode sponges dry, and impedance will naturally increase. SO, do not waste a large amount of time at this stage. You want to move to your task as quickly as possible. We have one more trick to help lower impedance if the pipetting isn’t doing the job.
To hold the electrodes in place and increase electrode contact with the scalp,cut two 4-6in. pieces of the tubular retainer net (which you will also find in the EEG Prep Supply box)to surround the net.
Place one band horizontally over the head like a sweat band, and the other perpendicularly under the chin and over the top of the head to cover all electrodes.
EGI User instructions can be found here: https://www.egi.com/images/stories/manuals/Second%20Batch%20of%20IFUs%20with%20new%20Notified%20Body%20Jan%202019/HC_GSN_MR_uins_8402110-01_20181221.pdf
6.5 Data Storage
Creating your Directory
Personal directories should be created in:
EGI –>Documents –> Net Station User Data –> Sessions
Net Station will automatically save any unnamed filed with no designated location to the Sessions folder.
Saving Files Before you start collecting data in Net Station, you’ll want to save it to a location where you can find it.
Locate the Waveform Recorder Controls panel (which can also be located in the Panels drop down).
Click New.
Name your file and save it to the desired folder.
Repeat steps 1-3 before every separate recording (block, trial,etc.) .
With any additional questions concerning your data storage, contact CCN Support at ccnsupport@g.ucla.edu.
Exporting Data
After data collection, many decide to export their data onto the Hoffman2 server; however, NetStation files are cumbersome to work with because of their size and format. Therefore, here are some data export instructions to convert and export files in your desired format:
6.6 Feedback Form
For quality control, we devised a feedback form that we ask researchers to fill out each time they collect data in the Staglin EEG Suite. Access to the form is located on the desktop of the Netstation computer, labeled steps 1 and 2:
Step 1 - logs you onto the Internet and pulls up the EEG Feedback Form
Step 2 - disconnects Internet. NOTE: This is important to do so the next tester will not be connected to the Internet while testing. Internet connection can disrupt recording.
The identification names of each net can be found on the plug.
6.7 Clean Up
After removing the net and unplugging it from the amp, wrap a dry towel around the plug. Remember, this plug must stay DRY, especially during the following process which involves a lot of water!
Rinse the Electrolyte Solution Out of the Net
In the prep room, dump the bucket full of electrolyte solution, rinse it with water once or twice, and fill it with warm water in the sink.
Place the towel-wrapped plug on a chair near the sink and submerge the electrode net (turned inside out, sponges out) into the bucket of water.
Rinse out the net by gently lifting it up and down and waving it back and forth in the water, allowing water to flow through the sponges.
Lift the net fully out of the bucket and dump the rinsing water.
Fill the bucket with warm water once again and repeat the rinsing process until you have rinsed the net a total of four times.
Once you see no more suds in the water and the net has been rinsed thoroughly , gently pat the excess water out of the net with a towel.
Disinfect the Net
Leaving the towel-wrapped plug on the chair, place the plastic bucket of premade disinfectant on the floor right in front of the chair. The disinfectant can be found on the floor of the prep room. It is the plastic bucket with the yellow top.
Submerge the electrode sensors in the disinfectant.
Gently plunge the net up and down allowing the disinfectant to move through the sponges for 1-2 minutes.
Leave the net to soak for 10 minutes. Set a timer! Soaking the net for a longer time may damage the net!
Mark a tally on the lid of the disinfectant. The suite administrator will monitor when it is time for new disinfectant to be made and prepare new disinfectant accordingly.
If you haven’t already, now would be a great time to fill out the Step d: Feedback Form by following the directions on the display of the desktop! It’l will only take a few minutes while you are waiting for the net to soak!
Rinse the Disinfectant Out of the Net
Follow steps 2-6 from Rinse the Electrolyte Solution Out of the Net above.
Hang the net by its connector to dry and place the empty rinsing bucket underneath to catch any drips.
Switch off the EGI Amp and lights, make the suite look tidy, and close the door when you leave the EEG suite.
References:
EGI Rinsing and Disinfecting Instructions The EGI instructions can be found in the black binder in the cabinet in the prep room.
6.8 EKG
A good tutorial (visual) for EKG application (we typically work with v2 and v4 in the eeg-fmri set up): https://www.adinstruments.com/blog/correctly-place-electrodes-12-lead-ecg
But here’s a quick step-by-step:
Use an alcohol wipe to clean the area between the pecs and directly below the left pec.
Place a dab of NuPrep on a cotton round and use this to scrub the same areas. This will remove a layer of dead skin cells.
Use another alcohol wipe to reclean the area.
Apply the two BioPac pre-gelled electrodes to the cleaned areas.
Make sure the lead wire is twisted together all along its length. Clip the leads to the BioPac electrodes so that they are pointing in opposite directions. This will reduce noise from induced magnetic fields.
Tape down the electrode/lead pairs.
Check the EKG signal in NetStation.