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HPIPlacementAndDigitization

HPI placement

-> * MEG alone In this case, HPI coils will be placed directly on the subject's scalp. The HPI coils should be placed as far as each other as possible at 4 specific locations on the head:

-> * MEG with EEG In this case, HPI coils will be placed on the EEG cap.

In both cases, affix the HPI with one double-face tape AND micropore tape. It is really important that HPI coils don't move during all the time of the MEG recording. It is recommended to scotchtape the cables of HPI coils on the right shoulder of your subject. Be careful to let enough length for the subject to move his head

Digitization with Isotrak system

 - 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.