- 3T setup
1.1 Before you start an experiment you should:
1.2 Starting an experiment
1.2.1 Participant & placing EEG net
1.2.2 Filling EEG channels (if gel cap is used) & setting up
1.2.3 EMG and ECG
We have a 256-channel 3T MR compatible Geodesic EEG system from EGI.
- check supplies in the control room, should contain:
- syringes
- electrode gel
- MR compatible (radio translucent) EMG/ECG electrodes
- alcohol pads
- measuring tape
- black/red pencils
- tissues
- fixomull stretch tape
- scissors
- check presence of PIB box with 10 extension cords
- turn on mini mac
- Login as spinoza-user, no password
- Go to Dock and Click on Documents ->Net Station User Data and scroll to the upper part and find in Acquisition Setup directory: 'Spinoza_protocol' and double click. You'll see the acquisition template with all necessary options.
- Introduce, show around, and explain what's about to happen and why. Answer questions if any. If participant is comfortable, participant can change to scanning outfit. Before placing cap:
- Measure circumference of participant's head to determine size of EEG net.
- Measure from bridge of nose to the back of the head. Mark middle using pencil.
- Measure from underneath the tragus (find 'dent' between jaw and ear). Mark it again.
- Select correct size EEG net (small: 54-56; medium: 56-58; large: 58-61 cm). All are in the cupboard in the control room.
- Place net so that ref Cz lead is on your mark and net is placed symmetrically:
- Place net as showed before and check if the net is placed symmetrically by looking at the midline that should correspond with the nose bridge, check also the back part and see if the net is placed in the middle and not shifted.
- If electrodes need to be shifted, do this by lifting rows of electrodes. Shifting then one by one will not be helpful. If you see that net is placed incorrectly, remove the net and place it again instead of lifting the electrodes.
- Make sure the electrodes on the cheeks are placed correctly around the eye. Make sure the plastic straps do not annoy the subject. Ask to blink a couple of times. Use the toggles and straps to tighten and control the net and cheek electrodes.
- Explain to the participant what's going to happen, what to expect, and that filling of electrodes don't hurt.
- Net Station is not yet operational. On the top of your screen, there is a yellow beam. On the far right, there are two options: 'off' and 'on'. Set it to 'on'. This will start monitoring. Make sure you close the window in which the EEG signals are shown.
- To check impedances, go to panels -> impedance. Opens a new window. Click 'measure impedance'. Shows new window with overview of EEG channels and its impedance color according to impedance threshold.
- Start filling the EEG electrodes. Start filling ref (Cz) and com (ground) electrodes, followed by the rest. Keep track of where you've been.
- After achieving good impedances, finish by clicking 'save and close'.
- To see waveforms: click on panels -> Dense Waveform Display OR go to the 'Spinoza_protocol' setup and click on the eye icon in the Dense Waveform Display box.
¶ EMG and ECG
Clean skin using alcohol pads -> dry skin using paper tissue -> put EMG were required and 2 ECG on chest (one below the collar bone and one below the sternum).In cases of alcohol allergy, use water and paper tissue.