Nitish Thakor introduces us to the electrocorticogram (ECoG). The ECoG is a measurement of brain activity by means of “a mesh of electrodes” inserted beneath the skull and draped over the surface of a brain – over the cerebral cortex to be precise. Next, the resulting signals are interpreted. “Raw ECoG signals appear to be a confused mess of squiggly lines with little discernible pattern. To make sense of the data, our team performs a spectral analysis to deconstruct the signal and find oscillations at certain specific frequencies. These are the brain waves you may have heard about. Neuroscientists have learned that different oscillation frequencies are associated with specific mental states, such as deep sleep, focused attention, or meditative contemplation.”
By means of ECoG neural prostheses become possible. “ECoG systems also hold the promise of being able to convey both motor and sensory signals. If a prosthetic limb has sensors that register when it touches an object, it could in principle send that sensory feedback to a patient by stimulating the brain through the ECoG electrodes.” Another option is speach prosthesis: “When ECoG electrodes are placed over the language areas of the brain, including the regions that govern the muscles of speech articulation, the resulting signals presumably carry information pertaining to both language generation and the physical production of words. A speech prosthesis could decode those signals and send commands to a device that would give voice to the patient’s intended sentences.”