How can I add the event label (ERPs) to the data recorded with OpenBCI? [resolved]
Hi.
I'm confusing with adding the event label to the data which I recorded with OpenBCI.
Could some one teach me how to do it?
Problem detail:
I recorded EEG data with OpenBCI(16chanel), and copy-and-paste the data to MATLAB.
I thought I can use the data in EEGLAB.
The problem is I want to add the event label to this data.
But I don't know how to do it. I can't look at the tutorial file "imag.set" because of text garbling.
(tutorial URL : "https://sccn.ucsd.edu/wiki/I.1:_Loading_Data_in_EEGLAB")
Q1. How should I add the data label? Is that OK, adding the event label just after the EEG(16CH) columns?
Q2. Does there any software which add label to the EEG data? Do I have to add label manually?
I'm glad if you answer the question! 
Comments
Yamada, hi.
ERP / P300 is usually done with an "external trigger" which is applied at the exact timing of your oddball stimulus (or control stimulus). This trigger value is recorded in the 'Aux' channels, which also carry the Accelerometer values. So there are three of these Aux channels. They can be switched to recording analog or digital values from the appropriate PIC32 pins on the breakout headers.
https://www.google.com/search?as_q=p300+trigger&as_sitesearch=openbci.com
https://docs.openbci.com/docs/02Cyton/CytonExternal
https://sccn.ucsd.edu/wiki/Chapter_03:_Event_Processing
https://sccn.ucsd.edu/wiki/A02:_Importing_Event_Epoch_Info
[see Importing events from a data channel]
Regards, William
Thank you for giving me good advice!
First of all, I want to understand what you have told me.
After that, I think I will hear again what I did not understand...
At that time, Thank you in advance again.
I'm sorry for my poor English ...
"Event labels" for ERP, usually correspond to the presentation of stimuli to the subject. These stimuli events can be recorded simultaneously along with the EEG channels, via the 3 'Aux' channels. The Aux channel input pins are on the PIC32 / chipKIT processor. Because external trigger events recorded in the Aux channels have exact timing correspondence to the simultaneous EEG channels, they are the most accurate source of event timing.
Hi Yamada,
Have you done with p300 ? If not then I can help you.
@Rafia
Sorry for the late reply.
I want to answer that question, but it's hard to answer because I don't know exactly what I'm doing ...
Perhaps it feels like a p300 or earlier problem. So maybe I didn't use p300.
I'm glad this is the answer you want.
@wjcroft
I am ignorant and ask questions that I do not understand, but please forgive me.
I haven't understood it yet, but is it that "Enabling Digital Read will record the ERP in the place where AUX was originally recorded" ...?
If so, does the ERP be recorded in three parts?
I also want to apply this ERP to EEGLAB. However, if you look at the EEGLAB event insertion page, you will see that fields like "Latency" and "Type" are set.
Is the ERP stored in AUX divided in this way for each field? Or do you have to sort it out yourself?
Since I am not good at English, this reply is very hard to understand and may be difficult to read.
However, I am very happy if you answer.
Thank you.
hi @Yamada
If I understood clearly, you can use pin d17 and d18 for digital I/O. It will give event number, latency, type, urevent automatically. You will get exact event timing. Then you can also edit many more.
I posted this comment previously, it's the second item in this thread...
--
Yamada, hi.
ERP / P300 is usually done with an "external trigger" which is applied at the exact timing of your oddball stimulus (or control stimulus). This trigger value is recorded in the 'Aux' channels, which also carry the Accelerometer values. So there are three of these Aux channels. They can be switched to recording analog or digital values from the appropriate PIC32 pins on the breakout headers.
https://www.google.com/search?as_q=p300+trigger&as_sitesearch=openbci.com
https://docs.openbci.com/docs/02Cyton/CytonExternal
https://sccn.ucsd.edu/wiki/Chapter_03:_Event_Processing
https://sccn.ucsd.edu/wiki/A02:_Importing_Event_Epoch_Info
[see Importing events from a data channel]
Regards, William
The Aux channel or channels are recording the external trigger event. NOT "record the ERP". The EEG channels are recording the ERP. The external trigger, recorded in the Aux channel, corresponds to the exact timing pulse (leading or trailing edge), when your control or oddball stimulus is presented.
No, the Aux channel is recording your external trigger event timing. It's just a digital or analog leading / trailing edge that corresponds to when you present the oddball stimulus. You might possibly want to use TWO Aux channels, one for recording the trigger for the oddball stimulus. And the other Aux for recording the trigger for your control stimulus.
Thanks for clarifying @wjcroft!
hi @Rafia
Thank you for your reply.
I have a question.
Are the pins d17 and d18 recorded somewhere?
Where can I see event numbers, wait times, types, urevent and other results?
If there is something wrong, I'd be happy to let you know.
hi @wjcroft
Thank you for teaching me carefully.
I'm really sorry for my poor understanding.
I interpreted it as "AUX only records the timing of the event", is that correct?
Also, if I refer to this page, can I understand how to generate events?
I'm glad if you can tell me if something is wrong.
https://sccn.ucsd.edu/wiki/Chapter_03:_Event_Processing
https://sccn.ucsd.edu/wiki/A02:_Importing_Event_Epoch_Info
[see Importing events from a data channel]
@Yamada,
Hi.
Are the pins d17 and d18 recorded somewhere? Yes. You can see at the recorded txt file . There will be 4 digital columns. The last 2 are D17 and D18.
Where can I see event numbers, wait times, types, urevent and other results? You have to extract event info from either channel or file. Then you will get everything.
Feel free to ask me any questions. Also can email me.
[email protected]
There are only THREE Aux channels.
@Rafia
@wjcroft
Thank you for teaching me!
I will proceed with that as a reference.
@Rafia
Sorry for asking questions that are similar again and again.
Is "the recorded txt file" recorded by Openbci itself? Or was it recorded using a micro SD?
What should I do to extract event information?
I am very happy if you can answer.
@Yamada
It is recorded by OpenBCI otself. In file menu, there are option for event. I use "from data channel.
Did you read the links about "external trigger"? One of your EEG channels or an Aux channel, is dedicated to recording the precise event timing of when the stimulus is presented to the subject. In most P300, this is at the moment when the control or oddball stimulus is presented to the subject.
@Rafia
Thank you for teaching.
I will try various things!
@wjcroft
Thank you for your advice.
I may have still misunderstood the event a bit.
I will try to read it again.
https://www.google.com/search?q=p300+tutorial
https://backyardbrains.com/experiments/p300
I'm sorry to bother you. I have pressed the PROG button corresponding to D17 pin manually according to the instructions of the external trigger on the official website, and collected data. At present, no corresponding D17 channel data is found in the txt file. My question is: 1. Can I manually press the PROG button to record into the final txt data? 2. If so, where is the D17 data recorded? I hope I can get your help. Thank you very much!
Before starting the session, you must place the Cyton 'Aux' channels into 'digital' or 'analog' read mode. Using the corresponding Widget in the GUI. If you do not do this, then the Aux channels will show only the Accelerometer values, x, y, z.
William
I have opened the digital read widget in the GUI interface. After pressing the PROG button, the D17 in the widget will show 1. Does it mean that the digital read mode has been opened
I have opened the digital read widget before recording. The data of the AUC channel is all 0, but no 1 is found. What is the problem