Intracranial electrodes are
electrodes that are placed inside the
cranium. They record the activity of brain areas directly, as they are in direct contact with cells. Still used in
animal studies, intracranial electrodes are usually left within the skull for
extended periods of time, and sometimes are only removed after
death. They are not used in human research nowadays, except in extreme
circumstances, although they were used in the past before
ethics became such a big deal in
psychology.
Intracranial electrodes can record activity from specific brain regions, unlike
scalp electrodes, and their recording specificity is not interfered with by the skull or scalp.