[Simnibs-discuss] Coil position

[Mana Biabani]

Hi, 

I am using SimNIBS to simulate TMS-induced e-field and had two questions :

1- Is there any method to measure the exact distance between the coil and scalp surface? The 4mm default distance is not appropriate for my experiment; as the participants have EEG cap on and also there is a foam between the coil and the cap. Also, I’d like to account for the differences in the amount of hair, etc.  I was thinking to measure the minimum euclidean distance between the coil centre and the scalp but as far as I understood the coil centre coordinates are actually scalp positions. So, it shouldn’t work.

2- My second question was about coil angle. I am using the angles that Brainsight provides to make the transformation matrix as below :

[ m0n0	-m0n1	m0n2 	coil.center(1)
 m1n0	-m1n1	m1n2	coil.center(2)
 m2n0	-m2n1	m2n2	coil.center(3)] . 

Could you please confirm if this matrix is correct.  My understanding is that I need to inverse the y axis in Brainsight and it does not need any transformations (like MNI to subject space). Is that correct?

Greatly appreciate your help in advance!

Kind Regards,
Mana


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MANA BIABANI
Research Fellow

Turner Institute for Brain and Mental Health
Monash University
18 Innovation Walk
Clayton VIC 3800
Australia

E: mana.biabanimoghadam at monash.edu <mailto:mana.biabanimoghadam at monash.edu>














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