Hi:
I am new to LV. I am trying to perform offline analysis of the electromyographic signal from the blink reflex, but I need to condition the signal, which is quiet complex in my experimental setting. I am analyzing the blink imposed in an already contracted Orbicularis oculi muscle. The signal is mainly composed by an EMG segment previous to the electrical stimulus that evokes the reflex blinking. This segment of 60 ms serves for quantifying the basal level of activity. Then an electric stimulus is applied, and 9 to 12 ms afterwards appears the R1, a short lasting burst of EMG activity, mostly a two-peaked waveform that fades into a silent period until the second bout, the R2, appears. The R2 is more variable, seems as any fragment of EMG activity taken from any muscle. The signal is commonly obscured by the artifacts provoked by the inevitable movement of the recording electrodes during blink , by the electric shock that serves as stimulus, and finally, by the movement of the eyeball, which acts as a dipole. I need to stabilize the signal in a true baseline, before rectyfing it. Rectifying is necessary on purpose of averagingseveral trials without having any phase cancelation in the process. Finally, in the averaged signal, I want to mark latencies and calculate the area of R1, R2 and the silent period in between, automatically. The areas are calculated considering the mean of the EMG of the prestimuli segment. Most of the spurious activity that is required to remove is in a low frequency range.
Í have each signal in a txt.They are grouped in files considering experimental paradigm and subjects. I have already developed some VI´s for converting the txt to waveforms. But the real problem comes when i tried to filter them. I had previous experience processing emg signals from hand muscles, but now I could not find the way.
Sorry for the delay in posting.
