[Eeglablist] ERSP data export

[shirazi at ieee.org]

Hi Fran,

I don't know if there is any function in EEGLAB for this, but it is not also hard to average ERSP over time or frequency.
ERSP is a three-dimensional array (say F x T x S), the first dimension (F) is frequency, the second is time (T), and the third is the different sources from the cluster (S). So, if you average over T and then S, you will get the ensemble average spectral power. In another scenario, if you average over F and then S, you will get the ensemble average power at any given time.

BTW, if you want to average over a certain period or frequency, you can look up the time and frequency from the outputs of std_readdata (or similarly std_readersp). The first output of these functions is the STUDY, second is ERSP array, thirst is time range, and the fourth is the frequency range. You will see that the length of time array is the same as dimension T above (and similarly length(frequency) = size(ERSP,1)). Hint: usually length(times) = 200 😉

I hope it helps.

Best,
Seyed

--
Seyed Yahya Shirazi
Ph.D. Candidate, BRaIN Lab
University of Central Florida


-----Original Message-----
From: eeglablist <eeglablist-bounces at sccn.ucsd.edu> On Behalf Of Fran Copelli
Sent: Wednesday, March 4, 2020 1:34 PM
To: EEGLAB List <eeglablist at sccn.ucsd.edu>
Subject: [Eeglablist] ERSP data export

Dear list,

A past colleague of mine developed a script for exporting cluster data. For a given cluster, it exports power collapsed across a given time and frequency range for each component in said cluster, for each condition.
You end up with a .csv like this:
*CLUSTER 1*
*Component, Condition 1, Condition 2, Condition 3* *1, power value, power value, power value,* *2, power value, power value, power value*

*However,* this script was developed for older versions of EEGLab and MATLAB, and appears to no longer be working correctly. Despite an ERSP that appears to have desynchronization, the exported power values are never negative, and are usually outrageously high (i.e., 40).

Is there a function in EEGLab to export data in this way? Or, can someone recommend a script/process that they use for this same analysis? For context, I am doing a mu suppression analysis.

I can provide my colleague's script if required.

Thank you!

Fran

SMART Lab, Psychology Department
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