[FieldTrip] ft_preproc_hilbert questions

Max Cantor mcantor at umich.edu
Tue Oct 28 19:16:19 CET 2014


So this is not a specific method-based question, but something more general.

I've been slowly reading through bits and pieces of Mike Cohen's 'Analyzing
Neural Time Series Data' book, in an attempt to gain a better understanding
of how things like Fourier Transform, Wavelets, and Hilbert work on a more
fundamental level.

Fieldtrip does not have a built in Hilbert time frequency analysis (that
I'm aware of), but from having read through that chapter of Cohen's book
I've been able to effectively create a hilbert analysis of my own.

However, I was wondering if it would be possible to use ft_preproc_hilbert
(setting cfg.hilbert = 'complex', 'real', etc. in ft_preprocessing) to do
this in a more efficient and fieldtrip-compatible way. It seems I can use
this setting to get the analytic signal, phase, power, and other things,
but since this is on raw/epoched data, there is no obvious way I can think
of to apply a time or frequency series as in the other TFRs. It seems I
could either write a fieldtrip function from scratch, which I'm not
prepared to do, or write a function to reformat fieldtrip data to work
using the Cohen function, and then output it back into a fieldtrip
function, which would be fine but I'm more interested to know if the
ft_preproc_hilbert function can do what I want more efficiently.

*So boiling it down**, my questions are:*

1. Can cfg.hilbert parameter for ft_preprocessing (or ft_preproc_hilbert
called directly) be used as an ad hoc hilbert TFR, and if so what ad hoc
steps would one need to take?

2. If it cannot be used this way, what situations is it meant for?

Max Cantor
Lab Manager
Computational Neurolinguistics Lab
University of Michigan
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