UC Berkeley researchers pinpoint areas of brain linked with addiction

Researchers at UC Berkeley have determined the specific areas of the brain that value and interpret decisions, which they hope may lead to new treatments for individuals who struggle with addiction. By measuring the neural activity of macaque monkeys, researchers were able to pinpoint the two specific ways the brain makes decisions, which they explained in a study published Sunday in the journal Nature Neuroscience. They now understand that neural activity in the brain’s orbitofrontal cortex determines the value of decisions, while neural activity in the anterior cingulate cortex evaluates the difference between expectations and results, which is responsible for future behavior. “The brain is basically a computer, and the neuron is taking information and then giving information that they’ve calculated,” said Jonathan Wallis, associate professor of psychology at UC Berkeley and the principal investigator of the study. “This is the first time we’ve been able to show the specific computation to decision-making in specific areas of the brain. That was really the novelty.” While previous research has determined that these sections of the brain are dysfunctional in addicts, the new research explains how the damage leads to addiction. If these parts of the frontal cortex are impaired, addicts lack the signals that provide them with accurate information about how valuable a choice is, making it less likely that they will learn the consequences of their actions, according to Wallis. “If you’re an addict and this area is impaired, you may not realize your goals, and you potentially are not going to learn from unhealthy decisions,” Wallis said. Wallis and his team conducted the research by testing the neural activity of macaque monkeys as they played games that gauged their ability to make decisions. Researchers could measure the calculations that the monkeys were making in the different areas of the brain, which mimicked the way that humans make decisions. The researchers completed the experiment in 2006 and have spent the last five years analyzing the data. Although still a few steps in the future, the ultimate goal of the study is to use the results to treat for individuals with addictions. “Besides therapy, there is nothing we can do for someone that is severely addicted,” Wallis said. “So far no surgical or pharmaceutical treatments exist. By figuring out what is going on when healthy people are making decisions, we can figure out what is going wrong when addicts make bad decisions and find some ways to target these specific areas of the brain.” While the study has led to a greater understanding of how the brain values decisions, researchers will still need to further investigate how addictive drugs are valued in order to develop more effective treatments, according to Howard Fields, professor of neurology and director of the Wheeler Center for the Neurobiology of Addiction at UC San Francisco. “This is a new and important scientific advance,” Fields said. “It is likely that addiction involves dysfunction of the relation between valuation of outcomes and subsequent decision making. In other words, drugs become overvalued compared to other action outcomes. Only by understanding the relation of valuation to action selection will we fully understand how drugs become addictive. After we do that, we’ll be able to develop more effective treatments.”