Inconsistency in Gamma activity
srpatil
India
Hello,
I have little to no experience in Neuroscience. Then I started playing around with the Ganglion board and am learning a lot, Thanks to this wonderful community and the moderators.
The first couple of sessions I had, I was getting strong Gamma activity. William J Croft rightfully pointed out that it is most likely due to due to scalp EMG (https://www.frontiersin.org/articles/10.3389/fnhum.2013.00138/full). He remarked that the amount of EMG scalp noise differs for individual subjects. Typical gamma band (actual EEG) amplitude is very low, generally in the range of few microvolts.
In another session with the same subject (me), my Gamma values were low. More in the range specified earlier. What explains this inconsistency in Gamma activity ? Also I was using the SSVEP widget but I didn't find any correlation with my brainwaves. I was trying hard to focus on the blinking widget but I didn't see any change in the focus widget. The only tangible thing I have discovered till now is that I get a strong Delta wave when I blink my eyes.
Regards,
Suraj
Comments
Suraj, hi.
The "strong Delta wave" associated with your eye blinks, is also correlated with EMG / EOG muscle activity. The frequency of the activity just shows up in the FFT at delta range.
https://www.google.com/search?q=eog+eeg
The amount of EOG you see will depend on how close the electrode(s) are to your eyes. Sites farther back, such as Cz Pz Oz, will have less than frontal sites.
It's hard to say what is the explanation for the difference you saw, that was registered as gamma. Could be related to some transient tension you were having in that area of the scalp, eye tension, caffeine levels, etc.
Regards, William
It is not delta, but EOG. See this Backyard Brains explanation:
https://backyardbrains.com/experiments/EOG