[FieldTrip] Using PPC method

[Andreas Wutz]

Dear Julia,

your frequency resolution depends on the time window you give to the FFT (cfg.timwin). Increasing that window will increase your freq resolution.


________________________________
From: fieldtrip-bounces at science.ru.nl [fieldtrip-bounces at science.ru.nl] on behalf of Julia Coopi [juliacoopiza at gmail.com]
Sent: Monday, September 11, 2017 9:24 AM
To: FieldTrip discussion list
Subject: Re: [FieldTrip] Using PPC method

Dear Andreas,

Finally, I managed to get PPC result from fliedtrip, now I have a problem:  I am using mtmfft as method I wnat to have fine frequency resolution atleast I wan to have a point for each 1 hz. I have used
 cfg.foi       =2:1:80;

But it did't work, my output has a frequncy vector like this:[ 5 10 15 20 ... 80];

do you have any suggestion for better frequency resolution.
If any body has a suggestion, that woulb be great to share it.

Thanks,
Julia

On Mon, Sep 4, 2017 at 6:24 AM, Andreas Wutz <awutz at mit.edu<mailto:awutz at mit.edu>> wrote:
Dear Julia,

I did not see your error message. Maybe, your lfp data structure is still in a continuous recording format without a trial definition?

________________________________
From: fieldtrip-bounces at science.ru.nl<mailto:fieldtrip-bounces at science.ru.nl> [fieldtrip-bounces at science.ru.nl<mailto:fieldtrip-bounces at science.ru.nl>] on behalf of Julia Coopi [juliacoopiza at gmail.com<mailto:juliacoopiza at gmail.com>]
Sent: Sunday, September 03, 2017 11:14 AM

To: FieldTrip discussion list
Subject: Re: [FieldTrip] Using PPC method

Dear Andreas,

Thanks for your response, I am going through your suggestion. did you have any problem regarding the appending spikes and lfp. I got this error:

Error using ft_appendspike (line 112)
could not find the trial information in the continuous data

thanks.
Julia

On Mon, Aug 28, 2017 at 4:55 PM, Andreas Wutz <awutz at mit.edu<mailto:awutz at mit.edu>> wrote:
Dear Tianyang,

maybe it's a good idea to download the accompanying sample data from the tutorial and look if you can recreate the shown data structure. Then look closer into the values of the respective fields. That should give you a better grasp on what is required there.

I have not fully looked into the code but my feeling is that spikeTrials.timestamp is not of any further use and is just carried from the data structure before (which was not cut into trials and where the raw timestamps were useful). The timing of spikes relative to the trial zero point is fully described in the fields ".time", ".trial" and ".trialtime".
Best,
Andreas


From: fieldtrip-bounces at science.ru.nl<mailto:fieldtrip-bounces at science.ru.nl> [fieldtrip-bounces at science.ru.nl<mailto:fieldtrip-bounces at science.ru.nl>] on behalf of 马天阳 [tianyangma2013 at gmail.com<mailto:tianyangma2013 at gmail.com>]
Sent: Monday, August 28, 2017 5:31 PM
To: FieldTrip discussion list
Subject: Re: [FieldTrip] Using PPC method

Dear Andreas,

I still don't quite understand the tutorial.

spikeTrials =
         label: {'sig002a_wf'  'sig003a_wf'}
     timestamp: {[1x83601 int32<http://www.mathworks.com/access/helpdesk/help/techdoc/ref/int32.html>]  [1x61513 int32<http://www.mathworks.com/access/helpdesk/help/techdoc/ref/int32.html>]}
      waveform: {[1x32x83601 double<http://www.mathworks.com/access/helpdesk/help/techdoc/ref/double.html>]  [1x32x61513 double<http://www.mathworks.com/access/helpdesk/help/techdoc/ref/double.html>]}
          unit: {[1x83601 double<http://www.mathworks.com/access/helpdesk/help/techdoc/ref/double.html>]  [1x61513 double<http://www.mathworks.com/access/helpdesk/help/techdoc/ref/double.html>]}
           hdr: [1x1 struct<http://www.mathworks.com/access/helpdesk/help/techdoc/ref/struct.html>]
        dimord: '{chan}_lead_time_spike'
           cfg: [1x1 struct<http://www.mathworks.com/access/helpdesk/help/techdoc/ref/struct.html>]
          time: {[1x83601 double<http://www.mathworks.com/access/helpdesk/help/techdoc/ref/double.html>]  [1x61513 double<http://www.mathworks.com/access/helpdesk/help/techdoc/ref/double.html>]}
         trial: {[1x83601 double<http://www.mathworks.com/access/helpdesk/help/techdoc/ref/double.html>]  [1x61513 double<http://www.mathworks.com/access/helpdesk/help/techdoc/ref/double.html>]}
     trialtime: [600x2 double<http://www.mathworks.com/access/helpdesk/help/techdoc/ref/double.html>]

Like here, I don't know why for timestamp,time and trial, there are same number of values. If I have one unit, 60 trials and focus on -0.5 s to 0.5 s around stimulus event, I think trial means which trial of the 60 trials has spikes in this 1 s. The time means time point of spikes located in the 1 s around stimulus for each trial. Is it correct? But what about the timestamp? It means from the beginning of recording to the end and has nothing to do with trials?

I feel I am quite lost.

Best,

Tianyang

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