read NeuroScan avg file

[Robert Oostenveld]

Dear Seapsy

A file with an averaged ERP in it is treated just as any other file. The code below specifies that a single "trial/segment" should be constructed corresponding with the "average" event

cfg = []
cfg.trialdef.eventtype = 'average' % this is the important line
cfg.dataset = '0500e.avg' % this is a testfile I have
cfg = ft_definetrial(cfg);

% the following reads the data as a single trial
% this is also where you would do filters and baseline correction
raw = ft_preprocessing(cfg);

% the following "averages" the single trial, the consequence is just that the raw single-trial data representation is converted to a ERP data structure
avg = ft_timelockanalysis([], raw)

% please compare the raw and the avg data structure, the numbers representing the data are the same, only the structure is different

% the following plots the ERP
% my example file has channel names that correspond to the EEG-1020 layout, which is located in fieldtrip/template/EEG1020.lay
cfg = []
cfg.layout = 'EEG1010.lay'
cfg.interactive = 'yes'
ft_multiplotER(cfg, avg)

The cfg.interactive=yes option allows you to click in the figure select a subset of channels, over which you get the averaged ERP. In the following figure you can subsequently select the time window, resulting in the 3rd figure with the topography. See http://fieldtrip.fcdonders.nl/tutorial/plotting for more details on plotting and http://fieldtrip.fcdonders.nl/tutorial/layout for details on how to create a layout (which is a requirement for the plotting of the data on the correct 2D channel locations).

good luck
Robert



On 30 Nov 2010, at 14:47, Seapsy Seapsy wrote:

> dear all:
> i am the new fieldtripers.
> I got some  averaged *.avg files from neuroscan 4.3 Now i want to plot 
> topographic distributed with fieldtrip. But  i don't know how to convert the AVG 
> file to fieldtrip structure.
> Could anybody help me with this? 
> 
> 
> Thanks a lot
> 
> 
>              seapsy
> 
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You are receiving this message because you are subscribed to
the  FieldTrip list. The aim of this list is to facilitate the discussion
between  users of the FieldTrip  toolbox, to share experiences
and to discuss  new ideas for MEG and EEG analysis.
See also http://listserv.surfnet.nl/archives/fieldtrip.html
and http://www.ru.nl/neuroimaging/fieldtrip.
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