[FieldTrip] calculatng behavioral-power correlation

Juan Lei juan.lei at hotmail.com
Thu Jan 17 13:21:18 CET 2019

Dear Fieldtrip users and developers

I am confused about some information regarding calculating behavioral-power correlation.

on this pape http://www.fieldtriptoolbox.org/faq/how_can_i_test_for_correlations_between_neuronal_data_and_quantitative_stimulus_and_behavioural_variables/
How can I test for correlations between neuronal data and quantitative stimulus and behavioural variables? - FieldTrip toolbox<http://www.fieldtriptoolbox.org/faq/how_can_i_test_for_correlations_between_neuronal_data_and_quantitative_stimulus_and_behavioural_variables/>
It is important to make a distinction between categorical and quantitative independent variables, because these are associated with different test statistics.

in the examples for Quantitative Independent Variable, it seems that all parameter settings are the same for both ft_statfun_indepsamplesregrT  and ft_statfun_correlationT.  "design" only has one row with behavioural data, and only the brain data as Input for ft_freqstatistics:
                             n1 = 3; % n1 is the number of subjects

design(1,1:n1) = [0.6 0.9 0.1]; %here we insert our independent variable (behavioral data) in the cfg.design matrix, in this case reaction times of 3 subjects.
cfg.design = design;
cfg.ivar = 1;
stat = ft_freqstatistics(cfg, data_brain{:});

However, in another post https://mailman.science.ru.nl/pipermail/fieldtrip/2015-February/008950.html

[FieldTrip] calculating behavioural-power correlation<https://mailman.science.ru.nl/pipermail/fieldtrip/2015-February/008950.html>
Dear Frederic, >From my limited understanding, the way you specify your design matrix seems correct to me.I did the same thing as well, however, I was not interested in the correlation along the time dimension, and I averaged some frequencies to examine my behavioural-power change correlation with specific frequency bands (e.g. 2 - 4 Hz for Delta band, 4 - 8 Hz for Theta band, etc).

it says "create a variable for the behavioural measure such that the variable contains a powspctrm field with the behavioural information for every frequency" as the other Input for ft_freqstatistica. Here "design" has two rows.

                cfg.design = [];
                cfg.design(1,:) = [ones(1,lenght(Y)) 2*ones(1,length(Y))];
                cfg.design(2,:) = [1:length(Y) 1:length(Y)];
                freq_stat = ft_freqstatistica(cfg,AVG,dum);

Therefore the information is not consistent. Could someone help me understanding it?

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