stFFT Hann taper and imaginary coherence?

EEG
#1

Dear Mike,

I’m interested in (sensor-level) phase connectivity. In chapter 15 of your ANTSD book, you wrote that phase values from the stFFT cannot be interpreted the same way as those from a wavelet analysis, but that they can however often be used in a similar way (e.g., with ITPC). My question is: Can stFFT be used to compute imaginary coherence?

Cheers,
Kate

#2

Hi Kate. With wavelet convolution or filter-Hilbert, you get a phase angle for each time point: the phase angle time series. With an FFT, you get one phase value (per frequency) for the entire time window. That phase value is q in sin(2pif*t+q). But otherwise, yes, you can use them in the same way in phase-based analyses.