I want to calculate the alpha/theta ratio for our EEG datas. Do I have to use BrainVision for this or can I do it by myself?
if you are using Matlab, the easy way is to design a filter with 'butter' command setting the cutoff frequencies according to alpha or theta band and then use it on data with 'filter' command.
As alternative for matlab butter filters recommended above you might wanna use the EEGlab filter functions.
An alternative for filter functions in matlab is the FFT-function "pwelch" which transforms a given data segment into its frequency domain equivalent. You can for example deconstruct the signal into the frequency powers between 1 and 128 Herz with a resolution of 1 Herz. After that you simply extract and average the 8 - 13 Herz bins (alpha) and the 4 - 7 Herz bins (theta) - then you can divide alpha by theta.
Ok, so I think I just have to divided alpha by theta because I already extract both bands from the datas. Thanks!
About Alpha and Theta frequency bands, if you are doing experiments on different subjects, the frequency bands may not be the same for all of them.
You can take a look at this paper for more information:
"EEG alpha and theta oscillations reflect cognitive and memory
performance: a review and analysis" by Wolfgang Klimesch
Yes, it is true. In fact I want to compare two different groups of participants in a task so i do not know how can I use this alpha/theta ratio. My supervisor told me that it represent a shifting between both bands. Thanks for the paper!
% for your epoched data, channel 1 [spectra,freqs] = spectopo(EEG.data(1,:,:), 0, EEG.srate); % delta=1-4, theta=4-8, alpha=8-13, beta=13-30, gamma=30-80 deltaIdx = find(freqs>1 & freqs4 & freqs8 & freqs13 & freqs30 & freqs1 & freqs4 & freqs8 & freqs13 & freqs30 & freqs
- Badges
- Science topic
- Similar topics
- Correction