Dopaminergic Neuromodulation and Age-Related Changes of Curiosity-Dependent Memory Formation

• Applicant: Professor Dr. Nico Bunzeck
• Subject Area: Biological Psychology and Cognitive Neuroscience ; Human Cognitive and Systems Neuroscience
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 505656522

Curiosity is a form of intrinsic motivation to seek and explore new information. While such a view is primarily based on developmental and psychological studies in children and younger adults, the underlying neural mechanisms and possible age-related changes remain unclear. In younger adults, increased states of curiosity for unknown information (i.e. epistemic curiosity, EC) promote hippocampus-dependent learning and memory formation via the dopaminergic mesolimbic system. Although this parallels previous findings by suggesting a link between intrinsic curiosity and extrinsic reward motivation, there is no direct evidence that the effects of state EC on long-term memory are modulated by dopamine. State EC has similar positive effects on long-term memory in both young and older humans. This is surprising since the dopaminergic mesolimbic system typically degenerates during healthy aging, which should reduce the effects of state EC on long-term memory in older adults. One possible explanation is that age-related structural degenerations of the mesolimbic system are compensated by neural upregulation (i.e. enhanced activation of a brain region typically involved) or reorganization (i.e. additional activation of another brain region not typically involved). Therefore, the overarching goal of the project is to investigate the underlying psychological and neurobiological principles of curiosity. I will address the following research questions: (1) Is curiosity-dependent long-term memory formation modulated by dopamine? (2) How are the positive effects of state EC on long-term memory maintained during healthy aging, given that it is typically associated with structural degeneration of the dopaminergic mesolimbic system? I plan to use an established curiosity paradigm in combination with functional magnetic resonance imaging (fMRI) in two studies. Study 1 will employ healthy young and older adults and a double-blind, placebo controlled, between-subjects design including a dopamine antagonist (sulpiride). I expect that, in contrast to placebo, the dopamine antagonist will diminish the curiosity effect (at the behavioural and neural level) in both age groups but to a larger extend in older adults. Study 2 will use functional and advanced structural MRI in a group of young and older adults without psychopharmacological interventions. I expect that the curiosity-dependent memory benefit in older adults is associated with functional compensation of structural degeneration (either though upregulation or reorganization). The expected results would give further insights into the underlying mechanisms of curiosity processing, and they would provide missing empirical evidence for specific concepts in aging research (i.e. compensation by upregulation and reorganization).

• DFG Programme: Research Grants