Mirror neurons are brain cells in the premotor cortex. First identified in macaque monkeys in the early 1990s, the neurons—also known as “monkey-see, monkey-do cells”—fire both when a monkey performs an action itself and when it observes another living creature perform that same action. Though it has been impossible to directly study the analogue of these neurons in people (since human subjects cannot be implanted with electrodes), several indirect brain-imaging measures, including EEG, have confirmed the presence of a mirror neuron system in humans.
As expected, mu wave suppression was recorded in the control subjects both when they moved and when they watched another human move. In other words, their mirror neuron systems acted normally. The mirror neurons of the subjects with autism spectrum disorders, however, responded anomalously—only to their own movement.
“The findings provide evidence that individuals with autism have a dysfunctional mirror neuron system, which may contribute to many of their impairments—especially those that involve comprehending and responding appropriately to others’ behavior,” said Lindsay Oberman, first author of the paper and UCSD doctoral student working in the labs of senior authors V. S. Ramachandran, director of the Center for Brain and Cognition, and Jaime Pineda, director of the Cognitive Neuroscience Laboratory.
Another possible therapy would involve ordinary mirrors. Ramachandran has successfully treated amputees who experience pain or paralysis in their missing, or “phantom,” limbs by using a mirror reflection of their healthy limb to “trick” their brains into believing that the missing limb has been restored to pain-free motion. Since autistics’ mirror neurons respond to their own motion, the researchers say, perhaps their brains can be induced to perceive their own reflected movements as the movements of another human being.
“We have a long way to go before these therapeutic possibilities are a reality, but we’re that much closer now that we’ve linked autism to a specific region of the brain,” said Ramachandran. “More than just documenting a brain anomaly in autism, we’ve been able to relate symptoms that are unique to the disorder—loss of empathy and imitative skills—to the function of a particular circuit, the mirror neuron system.”