[FieldTrip] About calculation of total power in TFr analysis

[Pelt, S. van (Stan)]

Dear Tuna,

As far as I understand, the morlet-TFR example as used in the tutorial (http://www.fieldtriptoolbox.org/tutorial/timefrequencyanalysis) computes total (evoked and induced) power, per trial and time bin, and then averages over trials.

To compute total power in the 1000ms epoch, I would suggest using cfg.method=’mtmfft’. E.g., something like the following, assuming that your data is organized in trials in a variable called ‘data’. BTW, note that because of your 1000ms data epoch, the intrinsic frequency resolution of your data is 1 Hz (1/1), thus spectral power below 1 Hz will be poorly estimated.

cfg=[];
cfg.toilim=[0.0 1.0]; %1000ms time window
data_ep=ft_redefinetrial(cfg,data);

cfg=[];
cfg.pad=10;
cfg.method=’mtmfft’;
cfg.outpu=’pow’;
cfg.foilim= [0.1 40];
cfg.channel = ‘all’;
data_ep_pow=ft_freqanalysis(cfg,data_ep);

Hope that helps.

Best, Stan

--
Stan van Pelt, PhD
Donders Institute for Brain, Cognition and Behaviour
Radboud University
Montessorilaan 3, B.01.34
6525 HR Nijmegen, the Netherlands
tel: +31 24 3616288



From: fieldtrip-bounces at science.ru.nl [mailto:fieldtrip-bounces at science.ru.nl] On Behalf Of Tuna Cakar
Sent: maandag 9 mei 2016 17:26
To: fieldtrip at science.ru.nl
Subject: [FieldTrip] About calculation of total power in TFr analysis

Dear all,

Although I have been using Fieldtrip over a year for the ERP analyses mostly, I am new in this e-mail list. I want to ask a simple question that has been challenging for me.

Regarding the time-frequency analysis (Morlet), I would like to calculate the total power over 1000 milliseconds and 0.1-40 Hz range. I realised that the codes in tutorial provides the calculation of evoked power.

Could someone please help me with that?

Thanks very much in advance. Kind regards, best,

Tuna


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