Memory-based sequential decision making: neural computations and shaping effects of mood

How does our past experience guide the decisions we make about the future? When planning to achieve a goal, we call upon relevant memories of our past. For example, our memories contain information about what happened to us, what may have stood in our way, and how good those events were. Our decisions are also often influenced by mood. For example, if you are in a low mood, you can more easily imagine your plans going wrong. Such a pessimistic outlook related to a low mood - or an optimistic outlook related to a positive mood - may then affect your motivation to pursue your goals. It is well known that our mood leads to the recollection of memories with a similar mood quality, but my research will for the first time look at how this memory bias affects our decisions. Importantly, the effect of mood on decision-making is likely to have more serious consequences in more severe anxiety and depression, which affect the well-being of millions of people. Proposed Research and Prospective Outcomes My research aims to understand how memory is used to guide our decisions, how these decisions may be biased by mood, and the underlying fast neural processes in the brain. To pursue this, my experiments have healthy volunteers learn about different rewarding goals hidden in mazes, and asks them to make choices to pursue those goals or not. Pursuing a goal in everyday life usually involves multiple steps, for example, being accepted into an education program, completing the degree, and finally finding a good job. At each point along the way, we face some chance of failure. By including such a risk in my experiments, I can see how participants are balancing the rewards of a goal versus the risk that the goal will not be achieved. This balance, reflecting how optimistic or pessimistic people's choices are, is likely to vary greatly across individuals. My experiments will test how this variability may relate to differences in personality and mood, with an expectation that it will relate to low mood and depression. Further studies will also explore how creating a short-term positive or negative mood further pushes people toward more optimistic or pessimistic balancing of goals. To understand the underlying mechanisms in the brain that support our decisions, my experiments also use brain imaging. I use magnetoencephalography (MEG), a non-invasive technique that allows us to record very rapid neural activity from hundreds of different recording sensors arranged in a helmet-like device. Recently, using new techniques we developed in our group, I found that when one remembers a previous event, the brain very rapidly plays through the experience. My ongoing research suggests that the same rapid 'replay' may support the decisions we make about the future by playing through the steps to a goal during planning. Importantly, my findings continue to extend and translate to humans exciting recent research in rodents on replay of experiences in neurons in the hippocampus, a region critical for memory. Expected Benefits By illuminating how the brain supports our decision-making, my research will provide a foundation for future work in mood disorders such as anxiety and depression. Already, our large online studies will provide a high level of variability in depression symptoms, allowing us to examine the relationship between low mood and decision making. Discoveries from my research also have the potential to inform cognitive and behavioral therapy. For example, using behavior and brain imaging measures, I can characterize individual susceptibility to low-mood-related pessimism about the future. For vulnerable individuals, we can develop mental strategies for intervention, limiting mood-related pessimism. Finally, stress, which affects a large proportion of the population, is also likely to influence the use of memory in decisions, and my research can inform understanding of pervasive stress-related influences on behavior.