CNS 2013 Meeting: Monkeys Help to Make Sense of Our Decision-Making

“Studying how the brain makes decisions can help treat brain disorders of decision-making. It may eventually help us to improve the way we present information to people when they have to make decisions, like how to save for retirement or whether taxation is the best way to reduce consumption of addictive substances.”
– Michael Platt

With tax time here, many of us are making important financial decisions, such as how much to save for retirement. To help us better understand how we make these decisions, researchers are turning to monkeys. We share with our primate relatives key neural processes that contribute to our everyday decision-making, and cognitive neuroscientists are increasingly learning more about the specific brain regions and chemicals involved.

The relatively new field of neuroeconomics brings together neuroscience with economics, anthropology, and psychology to decode decision-making. “We have known for almost 40 years that humans often make decisions that are ‘consistently irrational,’ to borrow a phrase from the behavioral economist Dan Ariely,” says Paul Glimcher of New York University, who is chairing a session on April 16 at the 20^th annual meeting of the Cognitive Neuroscience Society (CNS) in San Francisco. “We know from the work of primate ethologists that many of our closest animal relatives are consistently irrational in the same ways. But why? Neuroeconomists seek to answer that question by trying to understand how the structure of brains gives rise to these irrationalities.”

While fMRI and other technologies can examine structural brain features, many of the features require direct examination of brain tissue to be understood. “Studies in animals thus provide a critical underpinning for studies of decision making in humans,” Glimcher says. “These animal studies allow us to ask detailed questions about the fine structure of the primate brain that cannot be asked in humans.”

As a result of these studies, we now know so much more than 20 years ago about the processes that govern our decision-making. “Today, we know the basic anatomical, mathematical, and pharmacological properties of the brain systems for learning the values of things,” Glimcher explains, and “we can now see brains making choices.” This knowledge sheds light on everything from the behavior of small groups of investors to how emotions inform good decision-making. “The impact of neuroeconomics is just beginning to be felt in our society at large, and that impact has been in a wide variety of areas,” he says.

Michael Platt of the Duke Institute for Brain Science has conducted a number of studies on non-human primates and decision-making and will be presenting at Glimcher’s session on both past and new work. He talked to CNS about the body of work and its significance.

CNS: Why do you study decision-making in monkeys?

Platt: Although brain-imaging studies in humans can provide valuable insight into what parts of the brain may be involved in decision-making, such studies cannot determine precisely how neurons in these areas signal information or how we can treat problems in these areas that may occur
in decision-making disorders. Monkeys provide a unique opportunity to precisely determine how specific brain regions contribute to decision-making, what happens when that brain region is shut off or
turned on, and how particular naturally-occurring chemicals may alter decision-making.

Rhesus macaques are ideal for such studies because their brains are so similar to ours in terms of structure and function. They show striking similarities to humans in variation in key genes that contribute to neural function, whereas other animals do not. They also exhibit similar decision-making behavior, even in social situations; in fact these behaviors are so similar both qualitatively and quantitatively that they should be considered homologous – serving similar adaptive function, derived from shared developmental pathways, and expressed through common brain mechanisms.

CNS: How does the work with non-human primates translate to humans?

Platt: We have shown direct correspondence between rhesus macaques and humans in a number of decision-making behaviors, including aversion to ambiguity, motivation to reward other individuals, and a sensitivity to “counterfactual” information about what might have been had a different decision been made. Our neurophysiological studies demonstrate that the same brain areas mediate these processes in macaques and humans. Moreover, we have found that treating monkeys with oxytocin – a neuropeptide important for parental and sexual behavior that contributes to social bonding – promotes prosocial decisions in monkeys, as it does in humans. Importantly, we are now determining precisely how brain cells in these circuits interact to generate these decisions.

CNS: What have been the most significant findings in your work?

Platt: There are three significant findings from our work. First, we now understand a lot about the way nerve cells in the brain help us to make decisions. Importantly, there is no single decision-making area
that makes our decisions. Instead, much of the brain interacts to produce a single behavioral choice.

Second, our work shows that humans and monkeys make decisions in similar ways using similar brain
pathways. Essentially, most of our decisions are made using a 30-million-year-old device.

Third, our ongoing studies suggest ways in which can improve decisions and treat neuropsychiatric disorders by developing treatments that shape decisions made by monkeys.

CNS: What do you most want people to understand about this research that you have not already shared?

Platt: Studying how the brain makes decisions can help treat brain disorders of decision-making. It may eventually help us to improve the way we present information to people when they have to make decisions, like how to save for retirement or whether taxation is the best way to reduce consumption of addictive substances. Studying these processes in animals is important because the basic components of the brain cannot be studied easily in people.

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The symposium “Emerging models of human and animal decision-making” will take place April 16, 2013, in the Grand Ballroom at the San Francisco Hyatt Regency during the CNS annual meeting (April 13-16, 2013). Speakers will include Michael Platt, Matthew Rushworth, Antonio Rangel, and Elizabeth Phelps.

Media contact: Lisa M.P. Munoz, CNS Public Information Officer, cns.publicaffairs@gmail.com