Dopaminergic prefrontal connectivity promotes schema-dependent learning

Le résumé fourni par la source

Long-term memory for novel information can be supported by presenting it within a known semantic context. This so-called congruency effect has long been described as an example for schema-dependent learning, but the underlying neural mechanisms still remain unclear. Therefore, we tested the hypothesis that dopamine plays a critical role through the regulation of prefrontal connectivity. In a double-blind between-subjects design, healthy humans received either a dopamine agonist (1.25 mg bromocriptine), a dopamine antagonist (400 mg sulpiride), or a placebo before the encoding of semantically congruent and incongruent words, while their brain activity was scanned using fMRI. Behaviorally, semantic congruency enhanced recognition memory on the next day in all three groups, and this effect was modulated by drug following an inverted U-shaped function. Specifically, the congruency effect was highest under placebo and significantly reduced by both the agonist and antagonist. On the neural level, subsequent memory effects for congruent items in the left inferior frontal gyrus and its connectivity with the left substantia nigra and right nucleus accumbens, respectively, were also modulated by drug in a quadratic fashion resembling the behavioral pattern. Our findings give novel insights by showing that schema-dependent learning is modulated by prefrontal dopamine and interconnected mesolimbic regions.

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