Diff for "SubjectPreparation" - Meg Wiki
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== Subject Preparation == = Subject Preparation =

=== Checks and wires ===
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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
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
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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.
The location of the coils needs to be recorded with a 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.
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attachment: [[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
for 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 intially.
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

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.

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 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.

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 for 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 intially. 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)