[FieldTrip] Estimate coherence between conditions?

[Maité Crespo García]

Hi Maria,
for obtaining the sources timecourses (aka virtual channels) you can follow the tutorials pasted below. 

Best,Maité

http://www.fieldtriptoolbox.org/tutorial/connectivity#extract_the_virtual_channel_time-series

http://www.fieldtriptoolbox.org/tutorial/shared/virtual_sensors#extract_the_virtual_channel_time-series


 

    El Lunes 26 de junio de 2017 12:02, Maria Hakonen <maria.hakonen at gmail.com> escribió:
 

 Hi Maria,
maybe in this case it is better that you export the sources timecourses, build a data matrix with them and treat them in the same way as you did with the channels. 

Best,Maité 

Hi Maité,
Could you please yet let me know how to get the sources timecources? source = ft_sourceanalysis(cfg, freq); only gives  source = 
         freq: 18    cumtapcnt: [180x1 double]          dim: [19 15 15]       inside: [4275x1 logical]          pos: [4275x3 double]       method: 'average'          avg: [1x1 struct]          cfg: [1x1 struct]
Best,Maria
2017-06-25 13:53 GMT+03:00 Maria Hakonen <maria.hakonen at gmail.com>:

Hi Maité,Thank you for your answer!I have managed to calculate the coherence between two conditions in the sensor space in the way you suggested. However, I haven't managed to calculate the coherence between conditions in the source space (i.e. Appendix 1 in http://www.fieldtriptoolbox. org/tutorial/coherence). ft_sourceanalysis doesn't have channelcmb. I wonder if anyone has any solutions for this?BTW. I didn't get the answer to my question in my email but found it from Fieldtrip archive. However, I have also got some other emails from fieldtrip discussion forum.Best,Maria
Hi Maria,
Here it is a possible solution. First, rename channels from one of both conditions: for example, for condition 2, {'ch01cond2', 'ch02cond2', ...}. Then, append the data from both conditions. In ft_freqanalysis introduce all the channels combinations you want: 

cfg.channel    = {'MEG' 'ch01cond2' 'ch02cond2' ...};
cfg.channelcmb = {'ch01' 'ch01cond2'; 'ch02' 'ch02cond2'};
As I understand, you could use the same channelcmb later on in ft_connectivityanalysis.
I hope it helps.
Best wishes,Maité

Dear FieldTrip experts,

I have just started to use Fieldtrip and would like to estimate coherence between MEG responses measured in two different conditions from the same cortical areas. The example in Appendix 1 is close to what I would like to do:
http://www.fieldtriptoolbox.or g/tutorial/coherence

However, in the example, coherence is calculated between the reference signal (EMG) and all MEG channels. Could it be possible to calculate coherence between each MEG channel in one condition and the same MEG channels in the other condition, that is: 
ch1 in cond1 vs. ch1 in cond2, ch2 in cond1 vs. ch2 in cond2, ... 

As far as I understand, the example in Appendix 1 would do this: 
ch1 in cond1 vs. all channels in cond2, ch2 in cond ch1 all channels in cond2, ...

Best,
Maria



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