Hi,

I had 2 questions relating to measuring global mean cortical thickness with the weighting factor of surface area

bh.thickness = ( (lh.thickness * lh.surfarea) + (rh.thickness * rh.surfarea) ) / (lh.surfarea + rh.surfarea)

1.) If this weighting is recommended, then shouldn't it be performed for each vertex in an exploratory whole brain group analyses (e.g., for one vertex in left hemi: lh.thickness*lh.surfarea)/(lh.surfarea).

2.) Are there any references that come to mind to cite in regards to this normalization technique?

I see that this following paper uses normalization (but was wondering if you would recommend any others):

Vuoksimaa, E., Panizzon, M. S., Chen, C.-H., Fiecas, M., Eyler, L. T., Fennema-Notestine, C., … Kremen, W. S. (2015). The Genetic Association Between Neocortical Volume and General Cognitive Ability Is Driven by Global Surface Area Rather Than Thickness. *Cerebral Cortex (New York, NY)* , *25*(8), 2127–2137. http://doi.org/10.1093/cercor/bhu018

Best, Mike