Forward Solution

The following script creates the forward model, from which the inverse operator will be computed. It is essential that you have created the [http://imaging.mrc-cbu.cam.ac.uk/meg/AnalyzingData/MNE_MRI_processing source space and BEM model, and realigned your MRI and MEG coordinate systems].

The script creates two forward solutions: One for MEG only (using only the inner skull surface), and one for combined EEG and MEG analysis (using inner skull, out skull and skin surfaces). If you only have MEG data, you can skip the latter. The main ingredients for this step are

* the source space (cortical surface)

* the BEM model (surfaces describing boundaries of different electrical conductivity)

* the MEG data (at this stage only sensor/electrode positions and MRI-MEG realignment)

The end product will be the forward solution file (something ending in *fwd.fif)

#

## Your variables:

path='<myMEGdatapath>'    # where your MEG fiff-files are
MRIpath='/myMRIdirectory/'    # where your MRI subdirectories are

# subjects names used for MRI data
subjects=(\
        'Subject1' \
        'Subject1' \
        'Subject1' \
)

# MEG IDs
subj_pre=(\
        'meg10_0001' \
        'meg10_0002' \
        'meg10_0003' \
        )

# MEG subdirectories    
subj_dir=(\
         '100001' \
         '100002' \
         '100003' \
        )
        
dirbem='subject'


## Processing:

nsubjects=${#subjects[*]}
lastsubj=`expr $nsubjects - 1`


# REPORT number of files to be processed:

for m in `seq 0 ${lastsubj}`
do
  echo " "
  echo " Computing forward & inverse solution for SUBJECT  ${subjects[m]}"
  echo " "
  
  subject=Subject${subjects[m]}


## setup model 3 layers (EEG+MEG)
mne_setup_forward_model --overwrite  --subject ${subject} --surf --ico 4
 
mne_do_forward_solution \
                        --overwrite \
                        --subject ${subject} \
                        --mindist 5 \
                        --spacing 5 \
                        --bem ${MRIpath}/${subject}/bem/${subject}-5120-5120-5120-bem-sol.fif \
                        --src ${MRIpath}/${subject}/bem/${subject}-5-src.fif \
                        --meas ${path}/${subj_pre[m]}/${subj_dir[m]}/MEGfile.fif  \
                        --fwd ${path}/${subj_pre[m]}/${subj_dir[m]}/lex_go_5-3L-EMEG-fwd.fif



## setup model 1 layer (MEG only)
mne_setup_forward_model --overwrite  --subject ${subject} --surf --homog --ico 4

mne_do_forward_solution \
                        --overwrite \
                        --subject ${subject} \
                        --mindist 5 \
                        --spacing 5 \
                        --megonly \
                        --bem ${MRIpath}/${subject}/bem/${subject}-5120-bem-sol.fif \
                        --src ${MRIpath}/${subject}/bem/${subject}-5-src.fif \
                        --meas ${path}/${subj_pre[m]}/${subj_dir[m]}/MEGfile.fif \
                        --fwd ${path}/${subj_pre[m]}/${subj_dir[m]}/lex_go_5-1L-MEG-fwd.fif



done # subject loop