Electrocorticography or ECoG is a method of neural interface in which an electrode array, quite like a fine mesh, is draped over the upper surface of the brain directly, under the skull. A section of the skull is removed to allow the array to be fed in, then replaced. The result is near-identical to a high fidelity EEG that is under the skull and thus away from its pattern dampening properties.

It has the advantage of far stronger brainwave detection and neural activity triangulation abilities than EEG, whilst at the same time, it does not cause the trauma to the brain that cutting into it for an implant does. The net does not lose signal strength and can sit in place practically permanently, gathering data.

The ECoG array fits under the skull, over the brain. Higher fidelity than a scalp EEG, lower invasiveness than a true implant.

Those undergoing epileptic seizures serious enough to require corrective surgery, are often the best opportunity for researchers to test such interfaces. If the skull's got to be opened anyway, and the patient agrees, why not use the opportunity to test such systems? This has been the case for nearly a decade now, in fact.

That ECoG nets work is now clearly proven. What work remains is to decrease the size of the array without losing data fidelity, or find a means to implant laproscopically, removing the need to take out a large section of skull. Chances are, both avenues will be pursued over the next few years.

References

Reading the Surface of the Brain

Brain-Computer Interface Technology Licensed to Neurolutions