Problem displaying ft_sourcestatistics results

Dear BS community,

I am using BS for source localization for EEG data. I was able to follow the guidelines of several tutorials in order to estimate the TF representation (using Morlet wavelet) on source data for full cortical maps.

Description of the dataset:
EEG data collected from 32 subjects, where we had three motor imagery conditions. Each subject performed N trials of motor imagery for each of the conditions, each lasting three seconds. We are interested in time-frequency analysis at the source level. Data was pre-processed using EEGLAB.
Here are the steps I followed:
For each condition:

  1. Downsample to 200Hz from 1000 Hz.
  2. Compute covariance matrix (pre-stim as baseline). Estimate the source for each trial using MNE (output is in pA.m)
  3. Compute TF maps for each trial (optimized for faster computation)
    • Avergae across frequency bands
    • Average every 50ms timebin
  4. Average TF maps across trials within a subject.
  5. Perform normalization for the averaged map using db method (10log10(activity/baseline)).
  6. Average maps across subjects.
  7. Plot the average time-frequency map.

I am able to see consistency between cortical maps and sensor level topographies for my frequency bands of interest.

My question:

  1. I would like to conduct statistical testing to compare conditions pairwise. Since I have the time dimension and the spatial dimension, the number of comparisons is huge. Reading through the documentation, I realized I can use cluster based permutation testing.
    What I tried already:
  • I tried to use process 2 to compare TF cortical maps for two of my conditions.
    I placed the 32 files (TF cortical maps) for each condition in one pane.

  • The process runs smoothly:

  • However, I get the error below when I try to load the outcome:

Hi @Haneensu, thank you for your detailed feedback.

Indeed, this is an issue on how TimeBands (and Frequency bands) are handled when the average on time (and on frequency) is requested for the ft_sourcestatistics.

We will fix this and come back once it is solved

1 Like

Hi @Raymundo.Cassani . Thank you very much for the quick response. Looking forward to the fix!!

@Haneensu, this is already solved in: 5eaf02b

Please update your Brainstorm instance to get the fix

3 Likes

Thanks, it works perfectly now.