Selective inactivation of adenosine A_2A receptors in striatal neurons enhances working memory and reversal learning

The adenosine A_2A receptor (A_2AR) is highly enriched in the striatum where it is uniquely positioned to integrate dopaminergic, glutamatergic, and other signals to modulate cognition. Although previous studies support the hypothesis that A_2AR inactivation can be pro-cognitive, analyses of A_2AR's effects on cognitive functions have been restricted to a small subset of cognitive domains. Furthermore, the relative contribution of A_2ARs in distinct brain regions remains largely unknown. Here, we studied the regulation of multiple memory processes by brain region-specific populations of A_2ARs. Specifically, we evaluated the cognitive impacts of conditional A_2AR deletion restricted to either the entire forebrain (i.e., cerebral cortex, hippocampus, and striatum, fb-A_2AR KO) or to striatum alone (st-A_2AR KO) in recognition memory, working memory, reference memory, and reversal learning. This comprehensive, comparative analysis showed for the first time that depletion of A_2AR-dependent signaling in either the entire forebrain or striatum alone is associated with two specific phenotypes indicative of cognitive flexibility - enhanced working memory and enhanced reversal learning. These selective pro-cognitive phenotypes seemed largely attributed to inactivation of striatal A_2ARs as they were captured by A_2AR deletion restricted to striatal neurons. Neither spatial reference memory acquisition nor spatial recognition memory were grossly affected, and no evidence for compensatory changes in striatal or cortical D₁, D₂, or A₁ receptor expression was found. This study provides the first direct demonstration that targeting striatal A_2ARs may be an effective, novel strategy to facilitate cognitive flexibility under normal and pathologic conditions.