[FieldTrip] What are the units output by ft_freqanalysis_tfr?

Eelke Spaak eelke.spaak at donders.ru.nl
Tue Jun 11 09:58:58 CEST 2013


Hi Aaron,

How are you plotting the data? If you are using
ft_single/multi/topoplotTFR, did you use baseline correction
(cfg.baseline = 'yes' or [begin end])? If you use cfg.baselinetype =
'relative' or cfg.baselinetype = 'relchange', data plotted will
typically be on the order of 10e-1. It represents ratio vs baseline
('relative') or relative change vs baseline ('relchange').

If you did not specify baseline correction, then there is something
else going on. In any case, ft_freqanalysis does not explicitly
transform/normalize units; it does not care about them.

Best,
Eelke

On 10 June 2013 18:11, Aaron Schurger <aaron.schurger at gmail.com> wrote:
> Hi,
> I am preparing figures for a paper, one of which is a time-frequency
> plot of the output from ft_freqanalysis (using the tfr method). The
> units of the data going in were on the order of 10e-11 or smaller (MEG
> data), but the units on the color (power) axis of the plot are on the
> order of 10e-1. Are the units normalized by default when you use
> ft_freqanalysis? If not then what are the units? The help on these
> functions was short on this kind of detail.
> Thanks!
> Aaron Schurger
>
> --
> Aaron Schurger, PhD
> Post-doctoral researcher
> INSERM U992 / NeuroSpin
> CEA - Saclay, France
> +33-1-69-08-66-47
> aaron.schurger at gmail.com
> http://www.unicog.org
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> fieldtrip at donders.ru.nl
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