Dear Diane,
Firstly, the figure you sent could only appear if you answered 'yes'
to 'Use headshape points?' Try answering 'no' for a start and see what
you get. Secondly, you should make sure that the fiducials you provide
in 'Prepare' are in the same coordinate system as your sensors. Try
plotting your sensor and fiducials together (using plot3) and see what
you get.
Best,
Vladimir
On Mon, Jan 18, 2010 at 12:32 PM, Diane Whitmer
<[log in to unmask]> wrote:
> Dear SPMers,
>
> I am confused about how to properly co-register custom EEG positions and the
> canonical MR template in SPM8.
>
> There are two places in the SPM8 work-flow that fiducials are requested:
> first in the Prepare > Load EEG Sensors process, and then subsequently in
> the Co-register dialog (with options to either Select, Type, or Click).
>
> I am assuming the first place is for loading custom EEG fiducials, and the
> second place is where you you specify MR positions. Is this correct?
>
> This was my custom EEG fiducial matrix (in voxels):
> x frontal-occipital, Y right-left, Z inferior-superior
> Nasion: 209 134 131
> Left Tragus: 68 118 8
> Right Tragus: 126 106 105
>
> For the EEG/MRI Coregistration gui, I selected "nas", "lpa" and "rpa."
>
> Attached is an image from the failed co-reg attempt.
>
> If anyone can tell me what I did wrong, I would greatly appreciate it.
>
>
> Thank you,
> Diane
>
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