About Brainstorm Broadband computation

1

Hi everyone!
I was wondering how does BS compute eeg analysis (e.g. psd, connectivity,etc) in bands (e.g. Alpha 8-13 Hz)

to compute psd in Alpha Band form 8 to 13 Hz is the same that compute psd for 8, 9,10,11,12 and 13 Hz and then compute the average?

in software like Fieldtrip they use the tapper function, but I think is not the same, instead, tapper is some kind of smooth function,

So my question is if compute some analysis from an eeg Band like Alpha is equivalent to compute individual Hz from that band and to average it?

Thanks in advance!

2

It depends on the method you use.

  • PSD: it computes the FFT for all the frequency bins (frequency resolution defined by the estimator window length), then averages the bins by frequency band.
  • Time-frequency with Morlet wavelets: computes the power at 4 equidistant frequencies in the input frequency band and then averages them
  • Time frequency with Hilbert transform, and some of the connectivity functions: filters the broadband signal in a given frequency band with a band-pass filter, and then computes measures from this filtered signal.
3

Thank you very much!
:smiley: