The Influence of Temporal Spacing on the Cognitive and Neural Systems Supporting Feedback Learning

• Applicant: G. Elliott Wimmer, Ph.D.
• Subject Area: General, Cognitive and Mathematical Psychology ; Human Cognitive and Systems Neuroscience
• Term: from 2016 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 317946335

Rewarding and aversive experiences exert a strong influence on later decision making. When making a choice between an apple and a banana, for example, our decision relies on values built across many experiences. In general, by learning over time which stimuli and actions regularly lead to favorable outcomes, we can make adaptive choices in our complex and changing world. Over the past few decades, neuroscience research has revealed the neural mechanisms supporting learning from reward feedback, demonstrating a critical role for the striatum and midbrain dopamine system. Simple feedback learning paradigms are increasingly being extended to understand learning dysfunctions in mood and psychiatric disorders as well as addiction. However, one important characteristic that this research ignores is the effect of time on learning: events in human feedback learning paradigms are only separated by several seconds, while learning events in the everyday environment are almost always separated by long periods of time. Importantly, early studies on feedback learning in the 20th century found that spacing of learning events strongly increased the rate of learning, suggesting a quantitative or qualitative shift in the underlying learning mechanisms. Remarkably, however, the effect of spacing between learning events on human reward learning has not been investigated. Further, human and animal research has not examined the neural basis of the beneficial effect of spacing on learning. Given that spacing defines most learning conditions in the everyday environment, our understanding of feedback learning mechanisms is likely to be incomplete. The current amended research proposal aims to understand the cognitive and neural mechanisms underlying the effect of temporal spacing on feedback learning. During my fellowship at Stanford, Experiments 1 & 2, reviewed below, examined behavioral and neural characteristics of reward-based feedback learning by manipulating spacing between learning events in a single session or across weeks. We found striking increases in learning due to spacing. At UCL, the proposed Experiments 3 & 4 will provide critical extensions to this work by examining behavioral effects of spaced learning in patients with major depressive disorder, neural activity in healthy young adults using MEG, and test how well-learned associations can be unlearned. The planned research we will take important steps in translating this work to understand learning dysfunctions in mood disorders, and the extension will allow for the completion of this work in the new institution. Overall, these studies will address a large gap in our knowledge of the fundamental processes of feedback learning, with potentially broad implications for our understanding of learning in mood disorders and addiction.

• DFG Programme: Research Fellowships
• International Connection: United Kingdom
• Host: Professor Raymond J. Dolan, Ph.D.