[[Electrocorticography]] (ECoG) measures brain electrical activity from beneath the skull in a way similar to non-invasive electroencephalography, using electrodes embedded in a thin plastic pad placed above the cortex, beneath the [[dura mater]].<ref>{{cite book | last1=Serruya | first1=Mijail | last2=Donoghue | first2=John | chapter = Chapter III: Design Principles of a Neuromotor Prosthetic Device | title = Neuroprosthetics: Theory and Practice | veditors = Horch KW, Dhillon GS | publisher = Imperial College Press | year=2004 |pages=1158–1196 | doi=10.1142/9789812561763_0040 | archive-url=https://web.archive.org/web/20050404155139/http://donoghue.neuro.brown.edu/pubs/2003-SerruyaDonoghue-Chap3-preprint.pdf | archive-date=4 April 2005 |chapter-url=httphttps://donoghue.neuro.brown.edu/pubs/2003-SerruyaDonoghue-Chap3-preprint.pdf}}</ref> ECoG technologies were first trialled in humans in 2004 by Eric Leuthardt and Daniel Moran from [[Washington University in St. Louis]]. In a later trial, the researchers enabled a teenage boy to play [[Space Invaders]].<ref>{{cite web | url = http://news-info.wustl.edu/news/page/normal/7800.html | title = Teenager moves video icons just by imagination | work = Press release | publisher = Washington University in St Louis | date = 9 October 2006 }}</ref> This research indicates that control is rapid, requires minimal training, balancing signal fidelity and level of invasiveness.{{refn|group=note|These electrodes had not been implanted in the patient with the intention of developing a BCI. The patient had had severe [[epilepsy]] and the electrodes were temporarily implanted to help his physicians localize seizure foci; the BCI researchers simply took advantage of this.<ref>{{cite journal | vauthors = Schalk G, Miller KJ, Anderson NR, Wilson JA, Smyth MD, Ojemann JG, Moran DW, Wolpaw JR, Leuthardt EC | display-authors = 6 | title = Two-dimensional movement control using electrocorticographic signals in humans | journal = Journal of Neural Engineering | volume = 5 | issue = 1 | pages = 75–84 | date = March 2008 | pmid = 18310813 | pmc = 2744037 | doi = 10.1088/1741-2560/5/1/008 | bibcode = 2008JNEng...5...75S }}</ref>}}
Signals can be either subdural or epidural, but are not taken from within the brain [[parenchyma]]. Patients are required to have invasive monitoring for localization and resection of an epileptogenic focus.{{Citation needed|date=May 2024}}
