Empathy Influenced by Brain Chemistry

Provocative new research suggests the neurochemical balance in a part of the brain influences our sensitivity to inequality.

Conceptually, this finding could lead to development of a pill that could make a person more compassionate.

University of California, Berkeley scientists believe they have taken a big step in that direction. Researchers at University of California, Berkeley and University of California, San Francisco found that giving a drug that changes the neurochemical balance in the prefrontal cortex of the brain causes a greater willingness to engage in prosocial behaviors.

An example of a prosocial behavior is a sense of fairness that ensures resources are divided more equally.

The researchers also say that future research may lead to a better understanding of the interaction between altered dopamine-brain mechanisms and mental illnesses, such as schizophrenia or addiction. This knowledge could potentially lead to diagnostic tools or treatments for these disorders.

“Our study shows how studying basic scientific questions about human nature can, in fact, provide important insights into diagnosis and treatment of social dysfunctions,” said Ming Hsu, a co-principal investigator and assistant professor at University of California, Berkeley’s Haas School of Business.

“Our hope is that medications targeting social function may someday be used to treat these disabling conditions,” said Andrew Kayser, a co-principal investigator on the study, an assistant professor of neurology at University of California, San Francisco.

As published online in the journal Current Biology, researchers provided study participants a pill containing either a placebo or tolcapone, a drug that prolongs the effects of dopamine, a brain chemical associated with reward and motivation in the prefrontal cortex. This intervention was performed on two separate visits.

Participants then played a simple economic game in which they divided money between themselves and an anonymous recipient. After receiving tolcapone, participants divided the money with the strangers in a fairer, more egalitarian way than after receiving the placebo.

“We typically think of fair-mindedness as a stable characteristic, part of one’s personality,” said Hsu.

“Our study doesn’t reject this notion, but it does show how that trait can be systematically affected by targeting specific neurochemical pathways in the human brain.”

In this double-blind study of 35 participants, including 18 women, neither participants nor study staff members knew which pills contained the placebo or tolcapone, an FDA-approved drug used to treat people with Parkinson’s disease.

Computational modeling showed Hsu and his colleagues that under tolcapone’s influence, game players were more sensitive to and less tolerant of social inequity, the perceived relative economic gap between a study participant and a stranger.

By connecting to previous studies showing that economic inequity is evaluated in the prefrontal cortex — a core area of the brain that dopamine affects — the new findings help researchers come closer to pinpointing how prosocial behaviors (such as fairness) are initiated in the brain.

“We have taken an important step toward learning how our aversion to inequity is influenced by our brain chemistry,” said the study’s first author, Ignacio Sáez, a postdoctoral researcher.

“Studies in the past decade have shed light on the neural circuits that govern how we behave in social situations. What we show here is one brain ‘switch’ we can affect.”

Source: University of California, Berkeley