Dear list,
I was wondering if the source code of MNE C API released? If yes, where can
I find it? Thanks!
Foucault
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Hello,
this question is not really related to MNE itself, but maybe someone has
seen something like this before (I am new to EEG analysis):
I did a fast Fourier transform on 6 second long segments and calculated
mean power values (averaged over electrodes, participants and 15 segments
each). What perplexes me is the power peak at approx. 38 Hz:
My steps for data preparation were as follows:
* band-pass filter of data (1 to 45 Hz)
* resampling from 512 Hz to 200 Hz
* cut recording into consecutive segments of 6 sec duration
* exclude segment if maximum allowed voltage step of 50 ?V is exceeded
* exclude segment if activity is lower than 0.5 ?V
* exclude segment if maximum and minimum amplitude exceed +/- 200 ?V
* exclude segment if maximum absolute difference of values in the
segment > 200 ?V
* retain only segments that are ok for all electrodes
* randomly choose 15 such good segments (all electrodes) from every
participant
* calculate FFT for every 2 sec time segment for every electrode and
participant
* calculate mean of all these FFTs
* plot
Has someone seen a similar peak before?
Thanks for any help and advice.
Nico
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Can you try the same analysis without the resampling step? Maybe there is
some aliasing of a line harmonic. How did you resample?
You can also try raw.plot_psd to see if the original unprocessed data has
it. That will tell you if something is in the original data, or if there is
a processing problem.
Eric
Hello,
this question is not really related to MNE itself, but maybe someone has
seen something like this before (I am new to EEG analysis):I did a fast Fourier transform on 6 second long segments and calculated
mean power values (averaged over electrodes, participants and 15 segments
each). What perplexes me is the power peak at approx. 38 Hz:My steps for data preparation were as follows:
1. band-pass filter of data (1 to 45 Hz)
2. resampling from 512 Hz to 200 Hz
3. cut recording into consecutive segments of 6 sec duration
4. exclude segment if maximum allowed voltage step of 50 ?V is exceeded
5. exclude segment if activity is lower than 0.5 ?V
6. exclude segment if maximum and minimum amplitude exceed +/- 200 ?V
7. exclude segment if maximum absolute difference of values in the
segment > 200 ?V
8. retain only segments that are ok for all electrodes
9. randomly choose 15 such good segments (all electrodes) from every
participant
10. calculate FFT for every 2 sec time segment for every electrode and
participant
11. calculate mean of all these FFTs
12. plotHas someone seen a similar peak before?
Thanks for any help and advice.
Nico
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Hi,
the MNE C code is not public but it has been shared in the past.
Why do you need access to it?
Alex
Hello Eric,
thank you so much for pointing out the function plot_psd. I wasn't aware of
this and it saves me a ton of work for testing...
My raw EDF files are too large so I only picked EEG channels, chose a
segment of only some minutes duration and saved the file without filtering
or resampling as a .fif file. Now plot_psd looks like this:
So it seems it is indeed in the raw data. Also, each obvious line peak (50
Hz, 150 Hz) seems to have smaller peaks 12 Hz apart. So it seems to somehow
originate from line-frequency electrical noise. Would you agree? If yes,
shouldn't that be an ubiquitous issue in EEG experiments?
Thank you
Nico
Quoting Eric Larson <larson.eric.d at gmail.com>:
Can you try the same analysis without the resampling step? Maybe there is
some aliasing of a line harmonic. How did you resample?You can also try raw.plot_psd to see if the original unprocessed data has
it. That will tell you if something is in the original data, or if there
is
a processing problem.
Eric
Hello,
this question is not really related to MNE itself, but maybe someone has
seen something like this before (I am new to EEG analysis):I did a fast Fourier transform on 6 second long segments and calculated
mean power values (averaged over electrodes, participants and 15
segments
each). What perplexes me is the power peak at approx. 38 Hz:
My steps for data preparation were as follows:
? ? 1. band-pass filter of data (1 to 45 Hz)
? ? 2. resampling from 512 Hz to 200 Hz
? ? 3. cut recording into consecutive segments of 6 sec duration
? ? 4. exclude segment if maximum allowed voltage step of 50 ?V is
exceeded
? ? 5. exclude segment if activity is lower than 0.5 ?V
? ? 6. exclude segment if maximum and minimum amplitude exceed +/- 200
?V
? ? 7. exclude segment if maximum absolute difference of values in the
? ? segment > 200 ?V
? ? 8. retain only segments that are ok for all electrodes
? ? 9. randomly choose 15 such good segments (all electrodes) from
every
? ? participant
? ? 10. calculate FFT for every 2 sec time segment for every electrode
and
? ? participant
? ? 11. calculate mean of all these FFTs
? ? 12. plotHas someone seen a similar peak before?
Thanks for any help and advice.
Nico
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Mne_analysis at nmr.mgh.harvard.edu
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it
is
addressed. If you believe this e-mail was sent to you in error and the
contains patient information, please contact the Partners Compliance
HelpLine at
MyComplianceReport.com: Compliance and Ethics Reporting . If the e-mail was sent to you
in
error
but does not contain patient information, please contact the sender and
properly
dispose of the e-mail.
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You might also consider looking at the Python code. Most of the heavy
lifting functions exist there now and it is open source with a BSD license.
Eric
Hi,
the MNE C code is not public but it has been shared in the past.
Why do you need access to it?
Alex
Dear list,
I was wondering if the source code of MNE C API released? If yes, where
can
I find it? Thanks!
Foucault
_______________________________________________
Mne_analysis mailing list
Mne_analysis at nmr.mgh.harvard.edu
Mne_analysis Info PageThe information in this e-mail is intended only for the person to whom it
is
If I had to guess, this is likely to be something that is specific to your site.
Best wishes,
Avniel
