I wanted to ask if it is possible to export to .mat file the conductivity values of a certain slice/volume of anatomical model? (in a similar way as we can export E-field)
As far as I know this is not possible, the best thing you can do is export the E-field and the J-distribution. Then through J=conductivity * E retrieve your conductivity. The same can be done with the permittivity (D = permittivity * E).
Hopefully this helps.