[Eeglablist] Power baseline substraction

Makoto Miyakoshi mmiyakoshi at ucsd.edu
Thu Mar 19 13:27:01 PDT 2015

Dear Arno,

This is a question about how to recover/convert STUDY ERSP using baseline
values. I've never done it before. Could you help us please?


On Wed, Mar 18, 2015 at 2:24 PM, Michal Vavrecka <vavrecka at fel.cvut.cz>

> Hello,
> I am using the eeglab for hemispheric assymetry calculation, so I need to
> create custom processing pipeline for the output of std_precompute. I know
> that the ERSP data are stored in *.erspdat file, that contains spectral
> power for each channel and also baseline (chanxx_ersp and chan_erspbase
> respectively). The problem is, that each matrix (or vector and matrix) are
> in different unit, so I do not know how to substract baseline and visualize
> results outside eeglab. The ersp matrix stores spectral values that range
> about [-8;8] that resembles spectral power in dB. Suprisingly the baseline
> values are stored in different units, ranging between 0 100. Can you write
> me how to convert baseline values to substract them from ersp data? Do I
> need to log the baseline or there is different transformation?
> Thank you for your help
> Michal
> Michal Vavrecka
> assistant professor
> Karlovo nam. 13
> Praha
> mail: vavrecka at fel.cvut.cz
> web: bio.felk.cvut.cz
> incognite.felk.cvut.cz
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Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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