Head Lines; April/May 2008; Scientific American Mind; by Katherine Leitzell, Sara Goudarzi, Emily Anthes, Christopher Intagliata, Rachel Dvoskin, Kurt Kleiner, Graciela Flores, Sandy Fritz, Erica Westly, Nicole Branan, Peter Sergo, Aimee Cunningham, Corey Binns, Karen A. Frenkel; 9 Page(s)

"You're never fully dressed without a smile," sang Little Orphan Annie in the Broadway musical. It turns out Annie may have been giving some shrewd advice--studies have repeatedly shown that people remember smiling faces better than neutral ones. Now researchers at Duke University have found a physical explanation for the phenomenon. Roberto Cabeza and his colleagues "introduced" volunteers to a number of people by showing them a picture and telling them a name. Using MRI, the investigators found that both learning and recalling the names associated with smiling faces preferentially activated the orbitofrontal cortex, an area of the brain involved in reward processing. Cabeza says that although the studies are preliminary, it makes evolutionary sense that a smile would be rewarding to the onlooker. "We are sensitive to positive social signals," Cabeza explains. "We want to remember people who were kind to us, in case we interact with them in the future."

One of the first things neuroscience students learn is that the brain's right hemisphere controls the left side of the body, and vice versa. Brain-computer interfaces, which employ brain signals to control an external device such as a robotic arm or a wheelchair, also utilize these opposing-side signals. Such technology is therefore unable to help victims of stroke and brain trauma, who often have one seriously damaged hemisphere that cannot be enlisted for motor commands.