PowerPoint Presentation

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¥Transformation proceeds in two stages:

1.Alignment of AC-PC and I-S axes (to +acpc coordinates)

2.Scaling to Talairach-Tournoux Atlas brain size (to +tlrc coordinates)

¥Alignment to +acpc coordinates:

²Anterior commissure (AC) and posterior commissure (PC) are aligned to be the y-axis

²The longitudinal (inter-hemispheric or mid-sagittal) fissure is aligned to be the yz-plane, thus defining the z-axis

²The axis perpendicular to these is the x-axis (right-left)

²Five markers that you must place using the [Define Markers] control panel:

AC superior edge

= top middle of anterior commissure

AC posterior margin

= rear middle of anterior commissure

PC inferior edge

= bottom middle of posterior commissure

First mid-sag point

= some point in the mid-sagittal plane

Another mid-sag point = some other point in the mid-sagittal plane

²This procedure tries to follow the Atlas as precisely as possible

åEven at the cost of confusion to the user (e.g., you)