Dopaminergic Modulation of Visual Attention and Working Memory in the Rodent Prefrontal Cortex

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Abstract
Converging evidence suggests that dopaminergic projections to the prefrontal cortex (PFC) modulate both attention and working memory processes that may be related to either insufficient or excessive dopamine activity specific to a D1 receptor mechanism. We examined the effects of bilateral intraprefrontal cortical infusions of the D1 agonist (SKF 81297) on a novel task specifically designed to assess the animals' ability to attend to a visual target (0.7 or 0.5 s) and then remember the location of that target over a variable delay (0–16 s) within the same test session. Bilateral prefrontal infusions of the low dose of SKF 81297 (0.01 g) had no effect on visual attention or memory throughout the entire testing schedule. The medium (0.06 g) dose preferentially increased attention to the stimulus target but only improved memory for that stimulus at a duration of 0.7 s, although in a delay-independent manner. The high dose (0.3 g) of the D1 agonist also increased attentional accuracy. However, it was only under the more attention challenging condition (0.5 s) that this high dose also produced a baseline delay-dependent modulation of memory for the stimulus target. Specifically, good memory at the short delay was impaired and poor memory at the long delay was improved. These data provide the first demonstration that dopamine D1 receptor stimulation sufficient to improve attentional accuracy, can also disrupt, and facilitate short-term working memory performance in a delay-dependent manner.