StaglinCenter:EEG:Net

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

1. In the prep room, grab an empty plastic bucket and fill it with warm water to the 2 quart line.

2. 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

1. Measure the circumference of the largest part of your subject's head in centimeters (usually sits right above the eyes).

2. 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:

1. 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.

2. 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.

3. Referencing your 2 marks, draw a cross at the intersection to find the vertex.

Soaking the Net

1. Wrap the towel around the plug of the previously determined net. This connection must always remain DRY!

2. 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.

3. 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

1. 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.

2. Turn the net back the right way (sponges in) and gently shake excess electrolyte solution from the net.

3. 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!

4. Instruct your subject to close his or her eyes.

5. 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.

6. 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.

7. 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 ( StaglinCenter:EEG:ImpedanceCheck ). 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.

References:

EGI Application Instructions

• The EGI instructions can be found in the black binder in the cabinet in the prep room.

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