[Eeglablist] EEGLAB data structure layout problems

[E.C. Rocheteau]

Dear List,

I'm having some problems with EEGLAB data structures, and I would be 
most grateful for any help. I'm a new user of EEGLAB, so please bear 
with me!

I had a problem with getting my data into EEGLAB from the software that 
I was using (TDT technologies; my data are LFPs, rather than EEG, from 
ferret auditory cortex). I ended up importing the data into MATLAB using 
a different route and then mimicking the data structure to produce:

EEG =

              setname: 'BIM100E06V'
             filename: ''
             filepath: ''
              subject: ''
                group: ''
            condition: ''
              session: []
             comments: []
               nbchan: 32
               trials: 28
                 pnts: 894
                srate: 595.4650
                 xmin: -0.5000
                 xmax: 1
                times: [1x894 double]
                 data: [32x894x28 single]
               icaact: []
              icawinv: []
            icasphere: []
           icaweights: []
          icachansind: []
             chanlocs: [1x32 struct]
           urchanlocs: []
             chaninfo: [1x1 struct]
                  ref: 'common'
                event: []
              urevent: []
     eventdescription: {}
                epoch: []
     epochdescription: {}
               reject: [1x1 struct]
                stats: [1x1 struct]
             specdata: []
           specicaact: []
           splinefile: []
        icasplinefile: ''
               dipfit: []
              history: '…'
                saved: 'no'
                  etc: []
           speiciaact: []
              datfile: ''

The data field is channels*frames*trials.

I have two questions really:

1: Do any of you see any problems with what I've done? Am I going to 
have problems further down the line from this data format?

2: My main problem is the 'chanlocs' field. My data is taken from a 4X4 
multielectrode array in the auditory cortex from each side of the head. 
I want to tell EEGLAB where the channels were located, but I don't have 
any form of location file from the recording software. I tried to 
manually do it like before, but it doesn't seem to be compatible at all. 
All I want, is for EEGLAB to plot it on a grid structure rather than a 
human head, taking the first 16 channels for the left side and the 
second set for the right side. If I could overlay that on a 2D picture 
of the cortex regions, that would be fantastic.

Here was my attempt:

EEG.chanlocs =

1x32 struct array with fields:

     theta
     radius
     labels
     sph_theta
     sph_phi
     sph_radius
     X
     Y
     Z
     ref
     type
     urchan

All the fields are empty except for X, Y, and Z, which I filled in with 
an arbitrary choice of regular grid coordinates, which I thought would 
have plotted it across two 2D grids.

Do any of you have any suggestions? I would be most grateful!!

-- 
Best Wishes,

Emma
Undergraduate Medical Student
University of Cambridge