Researchers have demonstrated a simple artificial neural circuit (news.ucsb.edu)

It doesn't get into the fact that they're using memristors until paragraph 8. They should really put that up front and center -- simple artificial neural circuits are old hat. :)

So they can scale up the strength of a connection. Can they also scale down the strength of a connection? You can't build a properly functioning neural network unless you dial the strength of the connection both up and down.