Abstract
Dopaminergic projections to the prefrontal cortex support higher-order cognitive functions, and are critically involved in many psychiatric disorders that involve memory deficits, including schizophrenia. The role of prefrontal dopamine in long-term memory, however, is still unclear. We used an imaging genetics approach to examine the hypothesis that dopamine availability in the prefrontal cortex ...
Abstract
Dopaminergic projections to the prefrontal cortex support higher-order cognitive functions, and are critically involved in many psychiatric disorders that involve memory deficits, including schizophrenia. The role of prefrontal dopamine in long-term memory, however, is still unclear. We used an imaging genetics approach to examine the hypothesis that dopamine availability in the prefrontal cortex selectively affects the ability to suppress interfering memories. Human participants were scanned via fMRI while practicing retrieval of previously studied target information in the face of interference from previously studied non-target information. This retrieval practice rendered the non-target information less retrievable on a later final test – a phenomenon known as retrieval-induced forgetting. The fifty-four participants were genotyped for the catechol-O-methyl transferase (COMT) Val108/158Met polymorphism. We found that COMT Val108/158Met genotype showed a selective and linear gene-dose effect on retrieval-induced forgetting, with the Met allele, which leads to higher prefrontal dopamine availability, being associated with greater retrieval-induced forgetting. Mirroring the behavioural pattern, the fMRI data revealed that Met allele carriers, compared with Val allele carriers, showed a greater response reduction in inhibitory control areas of the right inferior frontal cortex during retrieval practice, suggesting that they more efficiently reduced interference. These data support the hypothesis that the cortical dopaminergic system is centrally involved in the dynamic control of human long-term memory, supporting efficient remembering via the adaptive suppression of interfering memories.
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