UCLA Neuroscientists Pinpoint New Function For Mirror Neurons

A study by UCLA neuroscientists featuring functional magnetic resonance imaging and a well-stocked tea service suggests for the first time that mirror neurons help people understand the intentions of others -- a key component to social interaction.

Reporting Feb. 22 in the online edition of PLoS Biology, the UCLA team found that pre motor mirror neuron areas of the brain -- areas active during the execution and the observation of an action -- ascribe intentions to actions when presented within a context. Previously, these neurons were thought to be involved only in action recognition.

In addition to expanding knowledge of how the brain functions, the findings support a growing body of evidence that imitation-based forms of treatments in patients with autism and similar disorders may help stimulate the function of these neurons, helping these patients improve their ability to understand the intentions of others and empathize with their thoughts and feelings.

"Understanding the intentions of others while watching their action is a fundamental building block of social behavior," said principal investigator Dr. Marco Iacoboni, an associate professor in-residence of psychiatry and biobehavioral sciences at the UCLA Neuropsychiatric Institute's Ahmanson Lovelace Brain Mapping Center and the David Geffen School of Medicine at UCLA. "Our findings show for the first time that intentions behind actions of others can be recognized by the motor system using a mirror mechanism in the brain. The same area of the brain responsible for understanding behavior can predict behavior as well."

Twenty-three research subjects underwent functional MRI while alternately viewing three stimuli presented in the form of short videos: 1) a hand grasping a cup without context; 2) a tea service stocked with food and drink before use and after use, or context only; and 3) the grasping of a tea cup within each of the two contexts, signaling intent either to drink or to clean.

Actions embedded in context, compared with the other two conditions, increased blood flow in the posterior part of the brain's inferior frontal gyrus, known to be important for grasping control, and in the adjacent sector of the ventral premotor cortex, where hand actions are represented. Increased blood flow is an indicator of increased neural activity.

Iacoboni also is affiliated with the UCLA Brain Research Institute and the UCLA Center for Culture, Brain and Development. Other members of the research team included Istvan Molnar Szakacs and John C. Mazziotta of UCLA, and Vittorio Gallese, Giovanni Buccino and Giacomo Rizzolatti of the University of Parma, Italy.