1. Double check that the EEG module (amplifier) is in the desired speedmode. The default for EEG experiments in our lab is speedmode 4.
2. Measure the head circumference and write it down (56 cm tends to be the average). Select the appropriate-sized cap by studying a laminated copy of sizes chart that should be in the drawer along with all the caps.
3. Measure and write down the the distance between nasion and inion (usually around 36cm).

3. Clean the skin with alcohol in the following places:
   • behind the left ear (ref L)
   • behind the right ear (ref R)
   • next to the left eye (HL)
   • next to the right eye (HR)
   • above the left eye (VB)
   • below the left eye (VO).
4. Collect flat-type electrodes in number equal to the sites cleaned in the step above (Ex1 till Ex6).

Check that the electrodes are clean. There should be no left-over gel on any of the electrodes.

5. Hang the electrode cords from your neck to make sure they don’t touch the floor.
6. Don’t ever let the electrodes touch metal; take off your own jewelry!
7. Don’t pull the electrode cords; always handle the electrodes carefully by their plastic casing.
8. When sticking on the face electrodes keep in mind that the actual electrode is slightly off-center.
9. Put the electrode stickers on the face electrodes. Make sure the tip of the stickers is aligned with the wire of the electrodes; they will be easier to apply and less likely to fall off this way. Clean the skin with alcohol in the following places:
   1. behind left ear
   2. behind right ear
   3. next to left eye
   4. next to right eye
   5. above left eye (in line with the pupil)
   6. below left eye (in line with the pupil)
10. Get the face electrodes Ex1 and Ex2 and put a small jot of gel on them. Put them behind the left ear (Ex1) and the right ear (Ex2) on the skin covering the bony part of the skull there. This bony part is called the mastoids and the exact location differs from person to person so be sure to check. These electrodes will generally be used as a reference point for ALL of your pin-type electrodes so ensuring a correct location results in less noise.
    

    Here the bone procession is highlighted.

    The sternocleidomastoideus is the muscle you want to avoid putting the electrodes on. Source: Anatomy of the Human Body, 1918, H. Gray.

11. When aligning face electrodes, bear in mind that the actual electrode is off-center from where the plastic cap is. You may need to use some Kruidvat tape to keep the wires of face electrode 5 and 6 out of the participants’ field of vision. (Other than that, the face electrode stickers are secure enough to hold up the electrodes by themselves).
12. Put the cap on the participant’s head. Ask the participant to hold the front of the cap. Take out the label of the cap from under the cap, otherwise it will block [Iz].
13. Take the remaining four face electrodes, fill them with gel and put them on the face in this order:
    • next to left eye (Ex3)
    • next to right eye (Ex4)
    • above left eye (in line with the pupil) (Ex5)
    • below left eye (in line with the pupil) (Ex6)
14. Tape the wires of the face electrodes to the back of the subject, to avoid stepping on the electrodes.
15. Fix the chin strap with a possible additional of a pocket washcloth for comfort. Make sure that the cap is properly positioned:
    1. First, check visually whether the cap is centered on the participant’s head.
    2. Then, measure the spherical distance between the nasion and inion (~ 36 cm) and between the left and right ear.
    3. Adjust the cap so that [Cz] is dead middle of the above two distances (e.g. it should be 36/2 cm from nasion and inion).
16. Show the subject that the syringe doesn’t hurt by pressing it on your hand. Make sure you explain what you are doing clearly and calmly as it is important to keep the participant clear and calmly. Move the syringe a little bit to move away the hair. Fill the holes in the cap with gel (DRL and CMS first).
17. Click the electrodes in the cap, working back to front and aligning the wires so that they point towards the back of the participant. Make sure the codes match the labels on the cap! If you discover later that you made a mistake, write it down in your logbook. The normal layout is as follows:

    

    Top down view of the BioSemi Electrode Layout (#64)

    Top down view of the BioSemi Electrode Layout (#32 – identical to #64 layout except for CMS and DRL)

18. Switch on the amplifier via the button on the battery.
19. Click the electrode connector into the amp, at A and B. If the blue light does not stop blinking there is something wrong with [CMS] and/or [DLR] .
20. Note the cable number (set A/B) in your log book.
21. Click the face electrodes in the amp (match codes and colors to a default configuration or keep a note).
22. Make sure the participant is comfortable. You can move the chair down by stepping and leaning on the brace at the foot of the chair, and pump it up using the same brace.

Check the signal:

1. Start ActiView on the recording system (shortcut on the desktop).
2. At ActiView startup you get to select a configuration. Do one of the following:
   • Select the default cfg files (C:\Program Files (x86)\BioSemi\ActiView707\BioSemi_Default.cfg).
   • Select a .cfg file from the configuration folder (Desktop\Actiview Configurations\).
   • Or, write and select your own.
     

     About Actiview tab

3. Click on the tab ?electrode offset? to check the electrode connection of the electrodes. They should be below (+/-) 20mV ideally.
   

   Electrode offset

4. If the offset for a certain electrode is too high, wiggle the syringe around in the hole and get rid of air bubbles. If this doesn’t help: put in more gel for that electrode (but not so much that the blob of gel touches a blob of gel for another electrode – this is a bridge and means you’ll have to start all over again). Try this a maximum of three times; otherwise just write the electrode offset down on the participant form.
5. In case of weird signals, check this document to get an idea of what the problem is.

Start measuring:

1. Show the participant the signal and explain what different artifacts like a blink or a swallow can do to the signal. Explain when blinks are least wanted.
2. Test the intercom. Press 2 to turn on the intercom. Get the participant some water if you haven’t already. Switch off the airco if you have it running.
3. Go to the ‘Monopolar Display & Triggers’ tab, click on ‘Start’.
   

   Start measuring

4. You will now see the lines of the electrodes. If they are flat, the electrodes does not register anything. Make sure the electrodes are connected properly. Change the Trigger Format to decimal so that you can easily track where the participant is in the experiment by looking at the number codes. Next click ‘Start File’.
   

   Start file

5. In the ‘Select Save Options’ make sure the correct electrodes are selected (for 64 this is A + B), and the ‘Add 8 EX electrodes’ if applicable.
6. In the ‘Enter Local Subject Identification’ box enter the subject code.
7. In the ‘Enter Local Recording Identification’ box enter your capital initials (of the researcher). Press OK.
8. Enter a location and filename for your data; use the same subject code. If possible save under your own user account (D:/Users/[your username]/) so the files are registered to be yours. Press OK.

9. Click ‘paused’ to start measuring(!)

   Click Paused to start measuring

10. Check that there is a green button that says ‘saving’. Now you are measuring.
    

    Green button, measuring

11. Start your Presentation experiment from the ‘Main’ tab.
12. Select the scenario you want to run: make sure you have the correct number for that participant.
13. Click ‘Run’ to start the experiment.

It is possible to record a video of your session. Review the how-to Record Video With OBS and follow the instructions. Note that the participant should give informed consent for video capture.

ABR preparation: this is a special module that can be identified by having connectors on only the front panel!

1. Double check the ABR module (amplifier) is in speedmode 9.
2. Clean the skin with alcohol in the following places:
   • behind the left ear (ref L)
   • behind the right ear (ref R)
   • above left eye (CMS/DLR)
   • above right eye (DLR/CMS)
   • put a small alcohol soaked cotton on the head on equal distances from nasion and inion and equal distance from the left and right ear (Cz)
3. Collect the special 3 ABR cable and the CMS+DLR cable.

Check that the electrodes are clean. There should be no left-over gel on any of the electrodes.

5. Hang the electrode cords from your neck to make sure they don’t touch the floor.
6. Don’t ever let the electrodes touch metal; take off your own jewelry!
7. Don’t pull the electrode cords; always handle the electrodes carefully by their plastic casing.
8. When sticking on the face electrodes keep in mind that the actual electrode is slightly off-center.
9. Put the electrode stickers on the flat-type electrodes. Make sure the tip of the stickers are aligned with the wire of the electrodes; they will be easier to apply and less likely to fall off this way.
10. First place the CMS and DLR electrode and connect them to the module.
11. Get the ‘Left’ and ‘Right’ electrodes and put a small jot of gel on them. Put them behind the left ear and the right ear on the skin covering the bony part of the skull. This bony part is called the mastoid and the exact location differs from person to person so be sure to check. These electrodes will generally be used to pickup brain-step signals so placing them correctly is of substantial importance.
    

    Here the bone procession is highlighted.

    The sternocleidomastoideus is the muscle you want to avoid putting the electrodes on. Source: Anatomy of the Human Body, 1918, H. Gray.

12. Next, place the Cz electrode. This one is most difficult since it’s connection is made difficult due to the presence of hair. An alternative location is F1.
13. The blue LED on the amplifier should have stopped blinking now. If not: there is likely something wrong with the CMS/DLR.

Check the signal:

1. Start ActiABR-200 (shortcut should be on the desktop).
2. At startup you get to select your own configuration. Do one of the following:
   • Select the default cfg files (C:\Program Files (x86)\BioSemi\ActiABR200\BioSemi_ABRdefault.cfg).
   • Select a .cfg file from the configuration folder (Desktop\Actiview Configurations\).
   • Or, write and select your own.
3. At the left lower corner you should be able to view the offsets of the left, right, and active electrode. Use the ?electrode offset? to check the electrode connection of the electrodes. They should be below (+/-) 20mV ideally but (+/-) 40 mV is still feasible.
4. If the offset for a certain electrode is too high, try pushing on the electrode a bit. If this does not help, re-apply the electrode after removing it and cleaning the site.
5. In case of weird signals, check this document to get an idea of what the problem is.
6. Unlike the normal EEG the amount of recorded channels are number of ‘recording’ electrodes minus one. This is because the ABR module automatically references the left and right electrode to the reference (Cz).

Start measuring:

1. Show the participant the signal and explain what different artifacts like a blink or a swallow can do to the signal. Explain when blinks are least wanted.
2. Test the intercom. Press 2 to turn on the intercom. Get the participant some water if you haven’t already. Switch off the airco if you have it running.
3. Go to the ‘Monopolar Display & Triggers’ tab, click on ‘Start’.
   
4. You will now see the lines of the electrodes. If they are flat, the electrodes are not registering anything. Make sure the electrodes are connected properly. Change the Trigger Format to decimal so that you can easily track where the participant is in the experiment by looking at the number codes. Next click ‘Start File’.
5. In the ‘Select Save Options’ make sure the correct electrodes are selected (for 64 this is A + B), and the ‘Add 8 EX electrodes’ if applicable.
6. In the ‘Enter Local Subject Identification’ box enter the subject code.
7. In the ‘Enter Local Recording Identification’ box enter your capital initials (of the researcher). Press OK.
8. Enter a location and filename for your data; use the same subject code. If possible save under your own user account (D:/Users/[your username]/) so the files are registered to be yours.

9. Click ‘paused‘ to start measuring(!)

10. Check that there is a green button that says ‘saving’. Now you are measuring.
11. Start your Presentation experiment from the ‘Main’ tab.
12. Select the scenario you want to run: make sure you have the correct number for that participant.
13. Click ‘Run’ to start the experiment.

1. Put the battery in the charger if it’s charged below 25%.
2. Back up all your result files (.bdf file(s) from the recording system, Presentation logfiles (.log) from the stimulation system to the network storage (in your project folder on the L:\projects drive).
3. Clean all the electrodes by soaking them in hot water. Don’t use the (baby)toothbrush for the electrode sets, but only for the face electrodes. Be gentle; rough cleaning shortens the lifespan of the electrodes.
4. Gently dry the electrodes by patting them dry with paper. After the electrodes and face electrodes have been dried, hang them in the black electrode bag so that they’re not exposed to the light in the room. On general guidelines for electrode handling, corrosion and maximizing life span, see Electrodes_handling.pdf
5. Remove the electrodes from the cap and clean all the electrodes. Hang them to dry; make sure that the electrodes don’t drip on the connector.
6. Wash the cap with Ivory or Palmolive soap. Let it soak in lukewarm (not hot!!) water for a while first: this will get rid of most of the gel already. Use the tiny brush to go through each of the holes, and make sure you keep track of what row you’re cleaning. Cleaning it color by color can prevent you from losing track. After cleaning one hole, clean the little brush in the water so that the left-over gel doesn’t get put into the next hole. Scrub the fabric of the cap gently, and rinse the entire cap under the tap so that the remaining soap is gone. Also rinse the chin strap carefully. Hang the cap out to dry.
7. Clean up and order the room.
8. Unplug the Bose speakers’ adapter from the power outlet if you’ve used those for your experiment.
9. Check that the participant’s towel is hanged to dry (in K0.14). Also dry off the sink, and the counter. (Dry the sink to prevent lime scale; dry the counter to prevent the chipboard from softening, if the chipboard becomes soft the shower head attachment will become unstable).
10. Remember to notify tech support if any of the supplies are running short.
11. Return the lab key to where you got it from (Drift 6 or the key safe).
12. If there is a full load of laundry, take it to the laundromat at the Wittevrouwenstraat and get reimbursement from your own project money.
13. Two days after you’ve finished running your experiment, put the electrodes safely in a drawer, and take the battery of the charger.