Electrocorticography (ECoG)

Records the brain's electrical activity from a grid of electrodes placed directly on the brain's own surface, capturing a signal far sharper than a scalp recording without penetrating into the tissue itself.

References

• Buzsáki, G. "Large-Scale Recording of Neuronal Ensembles." Nature Neuroscience 7, no. 5 (2004): 446–451.