Abstract
We investigated the effect of bromocriptine, a dopamine agonist, on individual differences in behavior as well as frontal–striatal connectivity during a working memory task. After dopaminergic augmentation, frontal–striatal connectivity in low working memory capacity individuals increases, corresponding with behavioral improvement whereas decreases in connectivity in high working memory capacity individuals are associated with poorer behavioral performance. These findings corroborate an inverted U-shape response of dopamine function in behavioral performance and provide insight on the corresponding neural mechanisms.
Highlights
Dopamine is critical for working memory (Cools and D’Esposito, 2009), which refers to the temporary retention of information that was just experienced but no longer exists in the external environment, or was just retrieved from long-term memory
In our initial report of this data on the effects of bromocriptine on working memory function (Gibbs and D’Esposito, 2005), we found that the relationship between working memory retrieval processes and prefrontal cortex (PFC) activity was influenced by dopaminergic augmentation
PFC activity was correlated with memory retrieval rate after bromocriptine administration, whereas after placebo administration these measures were uncorrelated
Summary
Dopamine is critical for working memory (Cools and D’Esposito, 2009), which refers to the temporary retention of information that was just experienced but no longer exists in the external environment, or was just retrieved from long-term memory. Depletion of PFC dopamine or pharmacological blockade of dopamine receptors induces impairment on working memory tasks (Brozoski et al, 1979; Sawaguchi and Goldman-Rakic, 1991) and administration of dopamine agonists reverses these impairments (Brozoski et al, 1979; Arnsten et al, 1994). Dopamine in the striatum may rapidly update working memory representations in a task-relevant manner (Frank et al, 2001; Gruber et al, 2006). In support of these hypotheses, a human pharmacological fMRI study found that administration of the dopaminergic agonist bromocriptine modulated striatal and PFC activity during the flexible updating and stable maintenance of representations, respectively (Cools et al, 2007)
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