When the subject arrives at Neurospin
A nurse will first insure that:
* information about the study has been understood and agreed upon.
* the subject is devoided of any metal and wears a single-use pyjama.
The subject preparation is done in a consultation room next to the MEG suite. Thus, the next subject can be prepared while the previous one is still being recorded.
EOG & ECG electrodes placement
Note that the nurse will most of the time take care of this for you. This step will be performed in the consultation room. Ask the subject to lie down on the examination bed. EOG and ECG electrodes have to be placed on the participant as follows:
HORIZONTAL EOG Green & Red electrodes labeled HEOG: one above the left eye, one below the left eye
VERTICAL EOG Black & Blue electrodes labeled VEOG: one above on the left temple, one below on the right temple
ECG: Red & Green electrodes labeled ECG: one below the left clavicle, one on the right abdomen
GROUND: Black electrode labeled GROUND to be placed on the bone of the clavicle
Cleanse the skin with the abrasive Nuprep gel. Gently wipe the skin with an alcohol pad. Put a double-face-tape on the electrode. Fill the electrode with conductive paste EC2. Affix the electrode onto the skin.
For the ECG and GROUND electrodes in particular, maintain them into place with additional micropore tape.
HPI placement and digitization.
- The HPI coils should be placed as far as each other as possible at 4 specific locations on the head:
* one on the left and on the right mastoids
* one on the left and on the right forehead right below the hairline.
- Affix the HPI with one double-face tape AND micropore tape. - Bring the wooden chair away from the desk and from any metal. - Seat the subject on the wooden chair. - Put the Isotrak googles on the subject and secure its position by tightening the ropes - it is crucial that the googles remain in place. - check that the Isotrak unit is powered on (there is a switch in the rear panel) - log in the laptop (same credentials as on the MEG acquisition workstation) - start the PrepareAcquisition software on the laptop by clicking the corresponding icon on the desktop - select your project, select/enter the subject info, load your settings, and hit "Change" right next to HPI. - on the digitization window, click on "Coordinate frame alignment" to start the single-operator digitization - point the stylus and touch the left pre-auricular point (LPA) and click on the stylus once - repeat for the Nasion - repeat for the right pre-auricular point (RPA) - repeat for all four HPI coils in any order - digitize a few more anatomical landmarks (>20) starting with three points on the side of the nose and, for instance, following three lines along the scalp (2 lateral and 1 median). - Once all points have been digitized, click on the stylus away from the subject's head.
Subject placement in the MEG
Guide the subject to the MEG room and seat her/him in the MEG chair. Plug all EOG, ECG and Ground electrodes on the right panel of the MEG machine as follows:
* EOG vertical on channel 61 (EEG061)
* EOG horizontal on channel 62 (EEG062)
* ECG on channel 63 (EEG063)
Plug the HPI coils on the left panel of the MEG machine. The HPI plug only has 4 plastic pins while the MEG connector has five pins. Plug HPI coils at the back of the plug (The fifth pin, closest to you, is not used).