Sources of noise – neurocomputational underpinnings of non-greedy decision-making in youth and ADHD

• Applicants: Professor Dr. Lorenz Deserno; Dr. Maria Waltmann
• Subject Area: Human Cognitive and Systems Neuroscience ; Biological Psychiatry ; Developmental and Educational Psychology ; Clinical Psychiatry, Psychotherapy, Child and Adolescent Psychiatry
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 572000592

Children and adolescents show less consistent choice-behaviour than adults, erratically switching between options. This is often disadvantageous in laboratory tasks but could be adaptive in the long run. Because erratic decision-making favours sampling of less familiar options, it is hypothesised to function as a resource efficient form of exploration as a part of a long-term solution to explore-exploit dilemmas: gather knowledge and experience in youth, exploit it in adulthood. Though convincing in theory, the neurocognitive mechanisms of inconsistent choice-behaviour in youth are still poorly understood. Prior research suggests that rather than by explicit information-search, it is driven by random noise in the decision-making process. However, it has recently been shown that a large part of what looks like noise in the decision-making process may in fact reflect noise in the learning process. There is reason to speculate that learning noise may be a major driver of inconsistent decision-making in youth, but this has not been studied yet. The first objective of this proposal is therefore to determine the contributions and neural correlates of learning and decision noise to erratic choice behaviour from childhood to young adulthood. Erratic choice behaviour is exaggerated in attention deficit hyperactivity disorder (ADHD) as compared to typical development. Given its onset during childhood development, we hypothesise that this may reflect a delayed or incomplete transition to a balance in exploration vs. exploitation. If indeed erratic choice-behaviour in youth is predominantly driven by learning noise, then learning noise peak in ADHD. Recent evidence supports this notion, showing that impulsivity, a hallmark of ADHD, is specifically associated with learning noise. However, the direct association with ADHD has not yet been investigated. Therefore, the second objective of this proposal is to determine the contributions of learning and decision noise to erratic choice behaviour in ADHD. Methylphenidate (MPH), a first line treatment of ADHD, affects the reuptake of dopamine and noradrenaline, both of which have been implicated exploration and noisy decision-making. It is not yet clear whether and how MPH differentially affects decision and learning noise. The third objective of this research proposal is therefore to determine the effects of MPH on learning and decision noise, as well as its neural correlates. Myocardial contractions during the cardiac cycle are starting to be understood as important modulators of the signal to noise ratio in a variety of computations in the brain. Development, ADHD, and catecholaminergic medication have all been associated with cardiovascular changes. Therefore, the fourth objective of this proposal is to explore the interaction between learning and decision noise and cardiovascular changes during development, in ADHD and after catecholaminergic medication.

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr. Arno Villringer