Diff for "SubjectPreparation" - Meg Wiki
location: Diff for "SubjectPreparation"
Differences between revisions 1 and 34 (spanning 33 versions)
Revision 1 as of 2007-05-16 15:32:36
Size: 694
Comment:
Revision 34 as of 2009-04-28 09:25:04
Size: 2693
Comment:
Deletions are marked like this. Additions are marked like this.
Line 1: Line 1:
== Subject Preparation == = Subject Preparation =
Preparation procedures can be done by both researchers and operators. The intention is for researchers to take the lead in this process using operator's help only when required. If you are not sure how to do the preparation, read these guidelines, and ask operators for further coaching. If you actively participate in the preparation, you can use your recording times much more efficiently: e.g., you can already prepare the next subject, when the operator is finishing the previous recording.
Line 3: Line 4:
Subjects need to be free of magnetic materials, like coins, watches
and other metal items. Underwired bras can be a problem, and even
dyes in clothing or hairdye can cause interference.
If you are also going to record EyeTracking data, you will have to make sure the participant isn't wearing any mascare. Using the eye tracker with the MEG compatible glasses is difficult. Contact lenses are no problem.
Line 7: Line 6:
To track head movements volunteers need to have 4 small coils attached
to ther head. 2 will be on the forehead and 2 behind the ears. In addition
we normally also attach 5 electrodes to the face to measure eye movements
and blinks.
=== Checks and wires ===
Subjects need to be free of magnetic materials, like coins, watches and other metal items. Underwired bras can be a problem, and even dyes in clothing or hairdye can cause interference.
Line 12: Line 9:
The location of the coils needs to be measured with a 3D digitiser. We also
measure 4 landmarks and a number of additional points on the head to indicate
headshape and enable easier matching to an MRI structural scan.
Subjects will need to complete a MEG Subject Screening Form, which will prompt them to remove all metal. This form can be downloaded from here: StandardOperatingProcedures
Line 16: Line 11:
attachment: To make sure that a subject is non-magnetic, it is good practise to put them in the MEG machine before any other preparation, and to check the signal for artefacts.

To track head movements volunteers need to have 4 small HPI (Head Position Indicator) coils attached to their head: 2 on the forehead and 2 behind the ears. In addition we normally attach 5 electrodes to the face as well to measure eye movements and blinks.

The location of the coils needs to be recorded with a Polhemus 3D digitiser. We also measure 3 landmarks and a number of additional points on the head to indicate headshape and enable easier matching to an MRI structural scan. The digitiser has a pen-like sensor that will record the location of its tip when the button is pressed. Full instructions on how to digitize can be found here: attachment:Digitizing.doc

In total, subject preparation should take about 20-30 minutes.

[[ImageLink(jason_subject.jpg,//CbuMeg, height=400)]]

The glasses in the picture have an additional sensor attached to them, to register movements of the head and correct for that. Fortunately, they are only used during the 3D recording process.

=== Seating the subject in the MEG ===
It is important that subjects are as high in the helmet as possible. Most people will relax during the experiment and often end up in a slightly lower position than initially. It is good practice to allow for a bit of time to seat the subject properly, perhaps try to add or remove one or more pillows and make sure they are as comfortable as possible.

Subject Preparation

Preparation procedures can be done by both researchers and operators. The intention is for researchers to take the lead in this process using operator's help only when required. If you are not sure how to do the preparation, read these guidelines, and ask operators for further coaching. If you actively participate in the preparation, you can use your recording times much more efficiently: e.g., you can already prepare the next subject, when the operator is finishing the previous recording.

If you are also going to record EyeTracking data, you will have to make sure the participant isn't wearing any mascare. Using the eye tracker with the MEG compatible glasses is difficult. Contact lenses are no problem.

Checks and wires

Subjects need to be free of magnetic materials, like coins, watches and other metal items. Underwired bras can be a problem, and even dyes in clothing or hairdye can cause interference.

Subjects will need to complete a MEG Subject Screening Form, which will prompt them to remove all metal. This form can be downloaded from here: StandardOperatingProcedures

To make sure that a subject is non-magnetic, it is good practise to put them in the MEG machine before any other preparation, and to check the signal for artefacts.

To track head movements volunteers need to have 4 small HPI (Head Position Indicator) coils attached to their head: 2 on the forehead and 2 behind the ears. In addition we normally attach 5 electrodes to the face as well to measure eye movements and blinks.

The location of the coils needs to be recorded with a Polhemus 3D digitiser. We also measure 3 landmarks and a number of additional points on the head to indicate headshape and enable easier matching to an MRI structural scan. The digitiser has a pen-like sensor that will record the location of its tip when the button is pressed. Full instructions on how to digitize can be found here: attachment:Digitizing.doc

In total, subject preparation should take about 20-30 minutes.

ImageLink(jason_subject.jpg,//CbuMeg, height=400)

The glasses in the picture have an additional sensor attached to them, to register movements of the head and correct for that. Fortunately, they are only used during the 3D recording process.

Seating the subject in the MEG

It is important that subjects are as high in the helmet as possible. Most people will relax during the experiment and often end up in a slightly lower position than initially. It is good practice to allow for a bit of time to seat the subject properly, perhaps try to add or remove one or more pillows and make sure they are as comfortable as possible.

CbuMeg: SubjectPreparation (last edited 2015-03-23 12:34:22 by OlafHauk)