[FieldTrip] Sample script for spike+LFP analysis?

Jay Hegdé jhegde at gru.edu
Tue Jan 21 10:20:18 CET 2014

Hi Eelke,

Thank you very much.  But I'm afraid this doesn't solve my problem.  My 
problem is not that I don't understand the nature of the trl matrix 
(which is easy enough to surmise by looking at ft_definetrial.m). 
Rather, it is understanding how the whole script is supposed to work -- 
which is why I was looking for a working script. (I haven't been able to 
find one in http://fieldtrip.fcdonders.nl/example.) So in this case, one 
script would be worth a thousand words for me.

Which is why I'd like to respectfully ask again: does anyone have a 
working script (plus a datafile, if the script does something other than 
spike-LFP analysis) that they can share?


On 1/21/2014 3:30 AM, Eelke Spaak wrote:
> Hi Jay,
> A "trl" matrix is an Nx3 matrix that gives, for each of N trials, the
> begin and end sample, and the 'offset' (shift in time axis to
> determine t=0; offset=0 means begin sample will be t=0).
> In typical cognitive experiments, such a matrix is generated by a call
> to ft_definetrial, which in turn calls either a user-specified
> "trialfun" to find events of interest in the data (recorded in a
> trigger channel), or ft_trialfun_general. ft_trialfun_general is a
> simple trialfun that looks for specified event values in a specified
> trigger channel, and creates trials spanning from X seconds before the
> event to Y seconds after the event. For using ft_definetrial, see this
> tutorial: http://fieldtrip.fcdonders.nl/tutorial/preprocessing
> If for any reason (e.g. you don't have triggers) you don't want to use
> ft_definetrial, you can simply create a trl matrix yourself by
> specifying the sample indices and offset.
> Best,
> Eelke
> On 21 January 2014 02:30, Jay Hegdé <jhegde at gru.edu> wrote:
>> Hi Everyone,
>> I'd like to use FieldTrip for the joint analysis of spike and local field
>> potential (LFP) data.  I'm proficient in Matlab, but very new to FieldTrip.
>> I'm trying to write a script by precisely following the relevant tutorial
>> (http://fieldtrip.fcdonders.nl/tutorial/spikefield). Everything goes OK for
>> the first couple of steps, but I'm getting stuck when it comes to
>> constructing "a cfg.trl matrix to preprocess the LFP data" described in the
>> tutorial.
>> So can anyone share an example script that actually runs and does this
>> analysis, so I can see what the tutorial is talking about?
>> Thank you very much in advance,
>> Jay Hegdé
>> Medical College of Georgia
>> Georgia Regents University
>> Augusta, GA, USA
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