How can I do time-frequency analysis on continuous data?

Discussions
1

Greetings,
I am trying to acquire a spectrogram for a long steady-state study. Naturally methods such as Morlet wavelet convolution are not applicable to lengthy and continuous data.
How can I have a Time-frequency plot for my lengthy steady-state Data (Hours long) using brainstorm?

2

Maybe something like the following?

  • Link the full continuous recordings to the database (menu Review raw file)
  • Epoch your data in regular blocks (a few seconds or a few minutes, depending on the time resolution you need), using the option "Split in time blocks" in the option window of the menu "Import to database"
  • Select all the epochs in the Process1 box
  • Select the process "Power spectrum density" or "FFT" to get a spectrogram for each block of data (you need to select the option "Save individual PSD values (for each trial)")
  • Add the process "Standardize > Concatenate time" immediately after, run the pipeline
  • In the new time-frequency file, the timing would not correspond to the original file: each time sample would correspond to the PSD of one block. You can edit the time vector manually in the file at the end if needed for display purposes.

I modified the concatenation process in order to create "timefreq" instead of "spectrum" file:
https://github.com/brainstorm-tools/brainstorm3/commit/c96ff6587826c718d26bbde5f5421d300cfa6e3f
Update Brainstorm before you try this.

1 Like
3

Dear Francois,
Exactly! I will try that right away.
Thank you for your help and support,
Sincerely,
Ali

4

Dear Francois , I have updated BrainStorm but I am still getting a spectrum file (FFT) instead of timefreq file after concatenation. Do I have to add the modified process manually ?

5

You need to recompute the concatenated files.

Please make sure that you have the following lines in the file process_concat.m:

If you don't: update Brainstorm again, something went wrong
Unless you are using the compiled version of Brainstorm?...

If you do: Please post a screen capture showing your file, including the blue tooltip that appears when you leave your mouse for a few seconds over the file (I'd need to know both the file name and the file path for the "spectrum" file).

6

Dear Francois, The new update works great for when I am using Matlab. But the compiled version is still the same. I would appreciate it if you could take a look at the attached image.

compiled

7

I haven't recompiled Brainstorm yet, and will not do it immediately since I'm working on other developments at the moment.
Please work with Matlab in the meantime.

8

Dear Francois, Certainly.
Thank you very much for your help

9

I've actually already recompiled Brainstorm.
You may now download a new version from the website.

Why do you use this compiled version if you have a Matlab license?

10

Dear Francois, thats good to hear !
Regarding your question, I do have the license on my personal computer, however sometimes I prefer to do work on a virtual machine using remote desktop because of its memory and processing power which is much higher than my PC. Since I dont have Matlab installed on that system I am using the compiled version there.
Best Regards,
Ali