Understanding the Desire to Explore-Value, Risk, and Learning in the Brain
Michael L. Platt, Duke University
Michael Platt is director of the Center for Cognitive Neuroscience and professor of neurobiology, evolutionary anthropology, and psychology at Duke University. His research focuses on the neuroethology and neuroeconomics of human and nonhuman primate behavior and cognition. Michael uses a broad array of techniques, including single neuron recordings, microstimulation, and neuropharmacology in behaving monkeys; eye tracking in free-ranging primates and birds; brain imaging in humans; and genetic association studies to understand how the brain makes decisions in uncertain and socially complex environments. Michael's research is motivated by ethology, evolutionary biology, and economics, with a focus on how specific features of the physical and social environment have shaped both decision-making and biology in different species. Michael received his BA from Yale and his Ph.D. from the University of Pennsylvania, both in biological anthropology. He then did a postdoctoral fellowship in neuroscience at New York University. His work has been supported by the National Institutes of Health, the Klingenstein Foundation, the Sloan Foundation, the McDonnell Foundation, the EJLB Foundation, Autism Speaks, and the Department of Defense. Michael's research has been featured in the New York Times, Washington Post, Wall Street Journal, Newsweek, and National Geographic, as well as on ABC's Good Morning America, NPR, CBC, BBC, and MTV.
Abstract: Whether you are a person driving home from work, a monkey foraging for food, or a rat navigating a maze, unexpected changes in the world require a shift in behavioral policy-rules that guide decisions based on prior knowledge-and potentially promote learning. Changes force individuals to draw upon reinforcement learning, task set switching, and attention, among other processes. The loci of change detection and subsequent policy adjustment within the brain remain unidentified. We propose that the posterior cingulate cortex (CGp)-a central node in the brain's default network-plays a key role in altering behavior in response to unexpected change, and in particular promotes exploration of alternative strategies. I will present evidence that neuronal activity in CGp varies with learning, memory, reward, economic risk, and task engagement. Further, I will show that increased activity in this area promotes exploration and predicts the speed of learning, and electrical stimulation in this area provokes sampling of alternatives. These observations suggest default network areas may be crucial for initiating transitions between basic modes of behavior, or even overriding them to generate new approaches to the world. Consistent with this model, a number of neuropsychiatric and neurological disorders, including depression, anxiety disorders, schizophrenia, Alzheimer's disease, and Parkinson's disease are associated with default-network dysfunction. These observations endorse the idea that a healthy CGp is necessary for organizing flexible behavior in response to an ever-changing environment, by mediating learning, memory, control, and reward systems to promote adaptive behavior.