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I recently received an Open BCI headset, and have been experimenting with it. One interesting is my brain gives off very regular pulses. My wife tested the headset too, and she also had these pulses. I'm not sure if this is some artifact of the headset, or if there is something like a 'brain beat' similar to a heart beat.

Here is an example readout from the headset's 8 channels.

enter image description here

The pulse frequency seems to change based on activity. Here is another sample after I've been chatting with some people online. You can see the frequency seems to have doubled, possibly due to increased cognitive load from interaction.

Is there a name for this phenomena, and is there any idea what it is?

enter image description here

One odd thing about the pulses is that they are synchronized across my brain. Here is an image of the 8 electrodes placement on my head, which you can see are spread across the top of my head from the front to the back.

Any idea what can cause the pulses to synchronize like this?

enter image description here

UPDATE: At Bryan Krause suggestion, I looked into whether it is some sort of cardiac pulse. To get ECG data, I attached two skin patches to my biceps and a ground to my elbow. The exact same pattern shows up. I'm guessing it is the electric pulse that drives my heart, but the strange thing is the pulse is much slower than my heart, and does not correspond too closely to my heart rate. For example, at rest I measured 8 beats per pulse. Then I did some exercise to elevate my heart rate. The pulses remained the same frequency but I now had 12 heart beats per pulse.

Here is a shot of the channels. Channel #1 is the ECG data, and rest of the channels are the EEG.

enter image description here

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    $\begingroup$ This is definitely an artifact. I'm not sure what kind, but you should read up on EEG artifacts if you plan to use EEG for anything. My first guess for something so rhythmic would be heartbeat, although if the time axis is correct it looks too slow. $\endgroup$ – Bryan Krause Nov 11 at 23:48
  • $\begingroup$ @BryanKrause I added ECG data to the question, showing it is the same signal across both ECG and EEG. However, it does not correspond clearly to my heartbeat. $\endgroup$ – yters Nov 12 at 1:07
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    $\begingroup$ Looks like a mix of heartbeat (the sharp spikes) and a muscle artifact of some sort (the bursts of high frequency activity). I don't know what 8-12 beats per "pulse" means, but these look spaced at 70-80 bpm which corresponds well to a typical heart rate. $\endgroup$ – Bryan Krause Nov 12 at 2:24
  • $\begingroup$ @BryanKrause I'm highly doubtful it is heartbeat. See the first image, where the pulses are spaced every two seconds. I don't believe my heartbeat is 30 bpm... I also tried the headset on a coworker today, and his signals were spaced every 5 seconds. $\endgroup$ – yters Nov 13 at 0:54
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    $\begingroup$ Yeah, I thought the same about the first image but wasn't sure if there might be a scale error - I guarantee you, though, that you haven't discovered some new brain rhythm. I don't know what the artifact is caused by for sure, but it's an artifact. Professionals that record EEG go to great lengths to avoid artifacts and process data to remove artifacts - it's a key part of electrophysiological recording. $\endgroup$ – Bryan Krause Nov 13 at 1:28
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Turns out these pulses are due to software latency in the OpenBCI GUI. One particular widget, the headshot widget, uses a lot of the CPU causing packet delay, and leads to the pulse pattern. Once the headshot widget is turned off, then the pulse artifact disappears.

https://github.com/OpenBCI/OpenBCI_GUI/issues/349

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