Researchers at the Boston hospital's Berenson-Allen Center for Noninvasive Brain Stimulation used rapid, repetitive stimulation to simulate what happens in the brain when people learn a new task. Then they gave a single pulse of stimulation and measured minute muscle twitches that told them how long people's brains maintained connections formed by the initial stimulation.In people with no evidence of autism, changes lasted about 30 minutes, on average. But in people on the autism spectrum, the initial stimulation caused brain changes that lasted much longer - on average an hour and a half.