Event Related Potentials (ERP)

What information is in EDF+ annotations?

The EDF+ specification defines additional type of signal, so called "EDF annotations" signal. In EDF+ file exported from WinEEG we have 5 different annotations. EDF specification does not prohibit having several such signals in EDF+ file. Moreover, the Polyman software actually reads EDF+ files with multiple "EDF annotations" signals without any problems. The Polyman simply combines all "EDF annotations" signals into one. You can do it the same way.Labels of the beginning ERP trial with number of trial [...]

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Independent components (ICA) of ERPs

These independent components of ERP linearly mixed will comprise the original averaged ERP signal. Each component is an independent piece of the ERP signal, representing a stage in the processing of the perception and then the motor aspects and then the cingulate’s self monitoring of the response. Though inter-related, each piece is a separate stage in the sequential process that creates the complexity of the ERP itself. In WInEEG software we apply Infomax ICA algorithm to decompose original ERP into [...]

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Subject response (patient button) processing setup for ERP analysis.

If you are using WinEEG+Psytask ERP system, the button response processing is programmed in WinEEG. When you record ERP you should connect patient response button to yellow socket of amplifier. You will see two red channel corresponding to clicking left and right button. To process subject respond channel while computing ERPs go to drop down menu Analysis—Compute ERP. Then you should select Digital 1 for left mouse button or Digital 2 for right button as shown below (arrow 1), after this go to next step (“Define” button, [...]

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WinEEG and e-Prime connection

WinEEG and e-Prime should work on different computers. WinEEG works on WindowXP PC but ePrime works on Windows 98 PC!!! We will call WinEEG computer as recording computer and ePrime computer as presenting computer. The main goal of connection is to synchronize the stimuli presentation process and EEG recording. e-Prime can send codes via COM port and WinEEG can catch this codes and recognize them as stimuli onsets. That is why the next steps should be done to setup this connection. 1.     Connect [...]

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What labels are exported to EDF+?

WinEEG can export to EDF+ format such markers as: Labels of the beginning ERP trial with number of trial typePatient response (with button) for GO task So you can see it below in Polyman software 3. Moments of the beginning photo-stimulation flash series of one frequency with digital label of this frequency in Hz and it looks like this: Other parameters (as user’s labels, markers of every photo-flash and so on) are not exported to the EDF+ files. Behavioral responses can be calculated [...]

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ERP dialog window tips

You can control X axis in the right panel as shown on the picture below, choosing the beginning and end of the time interval you want to see on a diagram. Two dashed vertical lines on the ERP plots mean the moments of appearance and disappearance of sound or image stimulus. The structure of a single trial in the task is shown below Pre-stimuli interval and other parameters are defined in Psytask software where you can set or change them. You can measure [...]

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