Brain-computer interface signal extraction methods range from non-invasive EEG to highly invasive implanted electrodes.

“You mentioned earlier there are at least two broadly, you know, two broad ways to extract that information. A non-invasive way where presumably you're putting electrodes all over a head that's as well shorn as mine. Um, alternatively, a very invasive way where you actually remove the scalp and you lay these things on the cortex itself. Correct. Yeah. So the range would be EEG which is where sensors are placed on the scalp directly recording non-invasively. You can remove them at any time. And then the far other extreme is uh electrodes that are actually placed into the brain.”