An international team led by researchers at Mount Sinai School of Medicine in New York has for the first time shown that one area of the brain, called the anterior insular cortex, is the activity center of human empathy, whereas other areas of the brain are not. The study is published in the September 2012 issue of the journal Brain.

Empathy, the ability to perceive and share another person's emotional state, has been described by philosophers and psychologists for centuries. In the past decade, however, scientists have used powerful functional MRI imaging to identify several regions in the brain that are associated with empathy for pain. This most recent study, however, firmly establishes that the anterior insular cortex is where the feeling of empathy originates.

"Now that we know the specific brain mechanisms associated with empathy, we can translate these findings into disease categories and learn why these empathic responses are deficient in neuropsychiatric illnesses, such as autism," said Patrick R. Hof, MD, Regenstreif Professor and Vice-Chair, Department of Neuroscience at Mount Sinai, a co-author of the study. "This will help direct neuropathologic investigations aiming to define the specific abnormalities in identifiable neuronal circuits in these conditions, bringing us one step closer to developing better models and eventually preventive or protective strategies."

Xiaosi Gu, PhD, who conducted the research in the Department of Psychiatry at Mount Sinai, worked with researchers from the United States and China, to evaluate Chinese patients, at Beijing Tiantan Hospital, who were shown color photographs of people in pain. Three patients had lesions caused by removing brain tumors in the anterior insular cortex; nine patients had lesions in other parts of the brain and 14 patients (the controls) had neurologically intact brains. The research team found that patients with damage restricted to the anterior insular cortex had deficits in explicit and implicit empathetic pain processing.

"In other words, patients with anterior insular lesions had a hard time evaluating the emotional state of people in pain and feeling empathy for them, compared to the controls and the patients with anterior cingulate cortex lesions." said Dr. Jin Fan, corresponding author of this study and an assistant professor at the Department of Psychiatry at Mount Sinai.

According to Dr. Gu, this study provides the first evidence suggesting that the empathy deficits in patients with brain damage to the anterior insular cortex are surprisingly similar to the empathy deficits found in several psychiatric diseases, including autism spectrum disorders, borderline personality disorder, schizophrenia, and conduct disorders, suggesting potentially common neural deficits in those psychiatric populations.

"Our findings provide strong evidence that empathy is mediated in a specific area of the brain," said Dr. Gu, who now works at University College London. "The findings have implications for a wide range of neuropsychiatric illnesses, such as autism and some forms of dementia, which are characterized by prominent deficits in higher-level social functioning."

This study suggests that behavioral and cognitive therapies can be developed to compensate for deficits in the anterior insular cortex and its related functions such as empathy in patients. These findings can also inform future research evaluating the cellular and molecular mechanisms underlying complex social functions in the anterior insular cortex and develop possible pharmacological treatments for patients.

The study was funded by the National Institute of Health, the James S. McDonnell Foundation and a Brain and Behavior Research Foundation NARSAD young investigator award.