[FieldTrip] mtmconvol time window

Roemer van der Meij r.vandermeij at donders.ru.nl
Wed Dec 19 13:21:00 CET 2012

Hi Julian,

Your first description is the what it reflects. If you have a cfg.toi =
0.15, the window will be centered at 0.15, going from 0 to 0.3.
If it helps, you can think of cfg.toi purely as a selection. The fourier
decomposition//wavelet convolution will be calculated for all samples in
each trial (with the window centered on each sample), the only thing
cfg.toi does is select which of those to keep as output. Cfg.toi will never
affect computation, only post-computation selection. To be more precise, in
mtmconvol you are doing a wavelet convolution in the time-domain by
multiplication in the frequency-domain. Timeoi and timeboi are used to
select those bits of the resulting complex time-series (and they reflect

All the best,

On Wed, Dec 19, 2012 at 12:30 PM, Julian Keil <julian.keil at gmail.com> wrote:

> Dear all,
> I have a rather specific question on the representation of the time window
> in the mtmconvol freqanalysis.
> In the help-file, it says that cfg.toi is the time vector, on which the
> analysis window should be centered, however as far as I can see in the code
> for the ft_specest_mtmconvol, the time of interest (timeoi), the time-bin
> of interest (timeboi) as well as the requested time bin (reqtimeboi)
> (ft_specest_mtmconvol, fieldtrip-20120815, line 280 ff) seem to suggest
> that the time I set in cfg.toi are actually the starting time for the
> spectrum estimation.
> In other words, if I'm looking to the 10 Hz signal and I set the
> cfg.toi=0.15 and cfg.t_ftimwin=0.3 in order to get 3 cycles of the 10 Hz
> oscillation, will the spectrum be estimated for the interval of 0ms to
> 300ms or for the interval of 150ms to 450ms?
> Thanks a lot!
> Julian
>  ********************
> *Dr. Julian Keil*
> *
> *
> AG Multisensorische Integration
> Psychiatrische Universitätsklinik
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Roemer van der Meij M.Sc.
PhD Candidate
Donders Institute for Brain, Cognition and Behaviour
Centre for Cognition
P.O. Box 9104
6500 HE Nijmegen
The Netherlands
Tel: +31(0)24 3655932
E-mail: r.vandermeij at donders.ru.nl
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