– Crebinostat is a novel cognitive enhancer that inhibits class I HDAC/1/2/3 (IC50=0.7/1.0/2.0 nM), class IIb HDAC6 (IC50=9.3 nM) with weaker inhibition of the class I HDAC8 and no significant inhibition of the class IIa HDAC/4/5/7/9; potently induces acetylation of both histone H3 and histone H4 as well as enhanced the expression of the CREB target gene Egr1 in cultured mouse primary neurons; upregulates Bdnf and Grn, and downregulates Mapt (tau) gene expression-genes; brain penetrant.