[FieldTrip] Importing .ses files

Ingrid Sör ingrid.sor at neuro.uu.se
Thu Jul 23 22:37:56 CEST 2015

Dear community,

My name is Ingrid Sör and am working at Uppsala University, Sweden, 
where we have recently started up a lab for studying speech and language 
related issues. At the moment I am trying my hand at analysing some 
trial EEG data with Fieldtrip (an oddball paradigm).

We are using the NeurOne software from MEGA Electronics, which renders 
data in .ses file format. I seem to be having trouble reading this 
format with ft_read_header, so I suspect it isn't supported (but I have 
read different accounts about this here 
<http://www.fieldtriptoolbox.org/dataformat> and here 
<http://www.fieldtriptoolbox.org/getting_started/egi>)? Maybe the file 
formats are also different depending on if they are from NeurOne or Net 

As far as I know, exporting to another format can't be done from 
NeurOne, as is suggested for Net Station. MEGA do supply Matlab 
functions to import the data though. But I thought I'd double check that 
the format actually isn't supported before I go down that route. I would 
also be glad to know if anyone has experience with using .ses data from 
NeurOne and know what alternative might be the best for importing to 
FieldTrip: reformatting the data structure rendered by the Matlab 
functions (from MEGA) to give compatibility with FieldTrip, or extending 
the FieldTrip reading functions to make them implement the .ses file 
format too?

Further below is some info about my code and the error, if the error 
could be explained by this.

Any help would be much appreciated.



This is the line I got stuck on, with the error message below.

cfg = ft_definetrial(cfg);

Warning: could not determine filetype of

 > In ft_filetype at 1221
   In utilities/private/dataset2files at 42
   In ft_checkconfig at 541
   In ft_definetrial at 128
Warning: no trialfun was specified, using ft_trialfun_general
 > In ft_definetrial at 135
evaluating trialfunction 'ft_trialfun_general'
Error using ft_read_header (line 2053)
unsupported header format (unknown)

Error in ft_trialfun_general (line 78)
hdr = ft_read_header(cfg.headerfile, 'headerformat', cfg.headerformat);

Error in ft_definetrial (line 174)
     [trl, event] = feval(cfg.trialfun, cfg);

My cfg structure looks like this:

cfg =

       trialdef: [1x1 struct]
       lpfilter: 'no'
     continuous: 'yes'
        channel: 'EEG'
         layout: 'EEG1020.lay'

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