Hi,
I’m trying to analyze EEG coherence from raw data acquired using ADInstruments’ LabChart.
I pick 30s epochs of raw data during resting state from two channels and export it to a txt file.
I use the spectral_connectivity function on list of epochs. Each element on this list is an array of 2 by 30000 (sampling freq: 1kHz). It appears to work fine when I’m using multiple epochs but when I take just one it show coh to be 1. over all chosen frequencies-- which means I’m not doing something right.
Here is the code I’m using:
import numpy as np
from pathlib import Path
from mne.connectivity import spectral_connectivity
fmin = (0.5, 4, 8, 12, 30, 60)
fmax = (4, 8, 12, 30, 50, 100)
sfreq = 1000
indices1 = (np.array([0]), np.array([1]))
lst = []
n = int(input("Enter number of epochs: "))
for i in range(0, n):
ele = str(input())
lst.append(ele)
data_set = [np.loadtxt(p, usecols=(1, 2)).transpose() for p in lst]
coh, freqs, times, n_epochs, n_tapers = spectral_connectivity(
data_set,
method="coh",
mode="fourier",
indices=indices1,
sfreq=sfreq,
fmin=fmin,
fmax=fmax,
faverage=True,
n_jobs=1,
)
I looked your coherence example (" Compute coherence in source space using a MNE inverse solution"), which, as far as I understands, deals with event related data. I scammed through the irrelevant parts and got to “Choose channels for coherence estimation” which I think might be related to my problem.
so I guess my question is-
Am I using the correct form of input data? why is not working on 1 epoch and whats stc and inverse operator has to do with it… since I have a basic background in signal processing I was looking for a rather straight answer on the web and couldnt find one.
Hope I was clear enough… Be happy to provide txt files of raw data if needed.
Thank you!! 