ECoG

Electrocorticography: recording brain activity with a sheet of electrodes placed on the brain's surface, without piercing tissue.

• Surgeons have long used it for days at a time to find where seizures start before operating on people with epilepsy.
• Each contact captures the combined activity of thousands of neurons, much sharper than EEG recorded through the skull.
• New thin films pack over 1,000 contacts; Precision Neuroscience's 4,096-electrode array won FDA clearance for up to 30 days' use in 2025.
• It can't resolve single neurons, yet surface arrays have decoded speech accurately; permanent surface implants are still in testing.