[FieldTrip] Freq baseline correction to separately recorded resting state file

[Schoffelen, J.M. (Jan Mathijs)]

Hi Matthew,

FieldTrip does not provide a ready-made function to do this. Yet, with a little bit of coding it can be done. You would need to make an estimate of the power (using ft_freqanalysis) of your baseline segments (ideally using the same parametrization of the (time-)frequency spectrum as you use for the data of interest. Then you’d need to average the baseline estimate across time (use ft_selectdata with cfg.avgovertime = ‘yes’) for that, and then you could use ft_math to do the baseline correction (after you have expanded the chanxfreq baseline powerspctrm back into a chanxfreqxtime matrix (repmat(freq.powspctrm, [1 1 numel(otherfreq.time)]);), either by subtracting the baseline power estimate, or do something more fancy.

Best wishes,
Jan-Mathijs




> On 22 Apr 2024, at 23:36, Matthew Mitchell via fieldtrip <fieldtrip at science.ru.nl> wrote:
>
> Dear Fieldtrip experts
> I am new to Fieldtrip and would very much appreciate insight on the below
>
> Instead of using the pre-stimulus interval for baseline correction after ft_freqanalysis, I would like to correct the post-stimulus segment to a separately recorded 2min resting state file (Biosemi) (recorded before an experiment).
> I am currently correcting the post stimulus segment to a [-2 -0.5] pre-stimulus period but I want to ascertain if this baseline period is 'clean' from the influence of the previous trial.
> any help is appreciated, thank you
>
> Matthew
>
>
>
>
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