Initially, Sestan said, they believed they had found such signals, generating both alarm and excitement in the lab, but they later determined that those signals were artifacts created by nearby equipment.
Sestan now says the organs produce a flat brain wave equivalent to a comatose state, although the tissue itself “looks surprisingly great” and, once it’s dissected, the cells produce normal-seeming patterns.
The lack of wider electrical activity could be irreversible if it is due to damage and cell death. The pigs’ brains were attached to the BrainEx device roughly four hours after the animals were decapitated.
However, it could also be due to chemicals the Yale team added to the blood replacement to prevent swelling, which also severely dampen the activity of neurons. “You have to understand that we have so many channel blockers in our solution,” Sestan told the NIH. “This is probably the explanation why we don’t get [any] signal.”
Sestan told the NIH it is conceivable that the brains could be kept alive indefinitely and that steps could be attempted to restore awareness. He said his team had elected not to attempt either because “this is uncharted territory.”