Thanks I managed to plot the channel on the brain!

However I ran into another problem: the channels are not perfectly placed on the cortex, especially the left hand side, as shown in the picture. It might have been caused by the interpolation that makes the two sets of coordinates not registered 1 to 1 as before? 

Is there a way to plot the brain as 80% transparent so that the channels can be seen without adjusting the depth? 


Many thanks,
Anyi