Wil, an Australian shepherd, waited to have his brain scanned in a magnetic resonance imaging machine, part of an experiment by Dr. Gregory Berns. Wil’s head is wrapped with medical gauze to hold in ear-plugs that muffle the noise.Credit...Dustin Chambers for The New York Times Dr. Gregory Berns, 53, a neuroscientist at Emory University in Atlanta, spends his days scanning the brains of dogs, tryi