PRX-07034 is both a potent (Ki = 4-8 nM) and highly selective 5-HT(6) receptor antagonist ( 100-fold selectivity for the 5-HT(6) receptor compared to 68 other GPCRs, ion channels, and transporters, except D(3) (Ki = 71 nM) and 5-HT(1B) (Ki = 260 nM) receptors.?For cyclic AMP quantification, PRX-07034 demonstrated antagonist activity (IC(50) = 19 nM) without an effect on basal levels and did not show any agonist activity up to 10 μM.?PRX-07034 at 1 and 3 mg/kg (but not 0.1 mg/kg) significantly enhanced delayed spontaneous alternation.?The drug at 1 and 3 mg/kg also enhanced switching between a place and response strategy, but did not affect initial learning of either a place or response discrimination.