[FieldTrip] Problem with preprocessed data extraction

[Schoffelen, J.M. (Jan Mathijs)]

Dear Dev,

In order to be able to troubleshoot this with you, it would indeed be helpful if we get a bit more detailed insight into what you have been trying to do exactly, and what code you used for that.

But first, I would start with inspecting the EEG data file’s header, by calling:

hdr = ft_read_header(<name-of-the-file>);

Among others, there should be a hdr.label field, which lists the names of the channels in a Nx1 cell-array, where N is the number of detected channels in the data file. N should be hopefully closer to 131 than to 16.

If you can confirm that N is sufficiently large, then I think that in principle the data is OK, and that you need to scrutinize the code you have been using, to try and understand the unexpected outcome.

Perhaps superfluously, but I assume that you also found the following piece of documentation online? https://www.fieldtriptoolbox.org/tutorial/continuous/<https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.fieldtriptoolbox.org%2Ftutorial%2Fcontinuous%2F&data=05%7C01%7Cfieldtrip%40science.ru.nl%7C73dc2dd3880d4ea8743c08dbd6c16217%7C084578d9400d4a5aa7c7e76ca47af400%7C1%7C0%7C638339898297341844%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=1R8f4l6KkEY0mqH5Pv0BZ61g9%2FhNlAK%2FPVMnuRTdASE%3D&reserved=0>, and https://www.fieldtriptoolbox.org/getting_started/brainvision/<https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.fieldtriptoolbox.org%2Fgetting_started%2Fbrainvision%2F&data=05%7C01%7Cfieldtrip%40science.ru.nl%7C73dc2dd3880d4ea8743c08dbd6c16217%7C084578d9400d4a5aa7c7e76ca47af400%7C1%7C0%7C638339898297495168%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=hKulr8QvZSjx19N%2BuQ0DZldZvDR5JVoUf9JebI9HEeI%3D&reserved=0>

Best wishes,
Jan-Mathijs

On 26 Oct 2023, at 22:43, Devika Duggal via fieldtrip <fieldtrip at science.ru.nl<mailto:fieldtrip at science.ru.nl>> wrote:

Dear Community,

I am a clinical psychology student working on a study about rejection sensitivity in a clinical population. We use a modified version of Cyberball that parametrically modulates the rate of exclusion and are collecting data using Brain Vision Recorder.

We are running into an issue relating to extracting waves from the preprocessed data and I am hoping to get some help with this. We preprocessed the data using FieldTrip but when we try to extract, only 16 of the recorded 131 channels are represented. All the channels were recording during data collection (as seen on Recorder) so we are not sure what happened. The channel names were also imported from Recorder for use in Fieldtrip.

I am new to EEG analysis so my apologies if I sound ignorant. If it is helpful to look at our FieldTrip code or some of our raw data, I am happy to send it over.

Best,
Dev

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https://doi.org/10.1371/journal.pcbi.1002202

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