Not sure how that would change anything. Think of the brain as a crowd at a soccer field and to decode the brain you'd need a mic on each person to capture every conversation. ECoG is like having a mic shared between every 100 people. While EEG is like having a single mic that is 10K feet over the soccer stadium.
This is my new favorite metaphor, if it's an analogy to how people sing, and how a person can sing somewhat randomly (free) yet controlled. The fact that there are two sides to the party chanting against each other, and the stadion speaker blurting over it occasionally, makes it so much better.
Corallary, you need two microphones at least for simplicities sake, although the repetitivenes of the chants makes it a little easier.
Most likely this will have good use in aphasia research.
