[Mne_analysis] mne_compute_raw_inverse gave perfectly correlated source current estimates

[Alexandre Gramfort]

Hello Kai,

a possible explanation is the "nave" used to set the regularization of
the inverse problem.

if you work with raw data, nave is 1 while with 100 epochs averaged
it's 100 and the inverse
solution is then far less regularized. A solution is to set the --nave
option to a higher value in
mne_compute_raw_inverse but you might amplify noise.

hope this helps

Alex

On Thu, Feb 23, 2012 at 3:02 AM, Kai Hwang <kai.hwang at gmail.com> wrote:
> Hello,
>
> I am trying to use mne_compute_raw_inverse to project single trial
> epochs onto the surface. The command finishes without erros, but is
> generating perfectly correlated source estimates from distant regions.
> The scale and sign of current estimates differ, but the correlation is
> either 1 or -1.
> Below is the command:
>
> #do forward solution
> mne_do_forward_solution --overwrite \
> --meas ${s}_prep_ave.fif --subject ${s} --fwd ${s}_prep_ave_fwd.fif --meg --eeg
>
> #create inverse operator
> mne_do_inverse_operator --fwd ${s}_prep_ave_fwd.fif --depth \
> --loose 0.2 --meg --eeg --senscov ${s}_prep_cov.fif --subject ${s}
>
> #project raw data, for each label
> mne_compute_raw_inverse --in ${s}_${rn}_sss_ds_raw.fif \
> --inv ${s}_prep_ave_fwd.fif-meg-eeg-inv.fif \
> --picknormalcomp \
> --align_z \
> --labeldir ./ALL-Labels \
> --orignames \
> --out ${s}-{rn}-label-source
>
> However, the same inverse operator worked fine with averaged evoked
> data, results are reasonable when viewed in mne_analyze.
> Any idea what could have gone wrong?
>
> Thanks!
> Kai
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