Based on the recording location, BCIs can be divided into:
(i) invasive, (ii) moderately invasive, and (iii) non-invasive
systems. Invasive BCIs involve electrodes or electrode arrays
that are directly implanted into the brain during a surgery.
They enable the highest quality measurements of neural activity.
Moderately invasive BCIs, such as electrocorticography
(ECoG) are implanted inside the skull, typically on top of
the brain.