Plays a role in signal transduction by regulating the intracellular concentration of cyclic nucleotides (PubMed:10373451, PubMed:10393245, PubMed:16330539, PubMed:17389385, PubMed:27058447). Can hydrolyze both cAMP and cGMP, but has higher affinity for cAMP and is more efficient with cAMP as substrate (PubMed:10373451, PubMed:10393245, PubMed:17389385, PubMed:27058447). May play a critical role in regulating cAMP and cGMP levels in the striatum, a region of the brain that contributes to the control of movement and cognition (PubMed:27058447). {ECO:0000269|PubMed:10373451, ECO:0000269|PubMed:10393245, ECO:0000269|PubMed:16330539, ECO:0000269|PubMed:17389385, ECO:0000269|PubMed:27058447}. This is the function of PDE10A (phosphodiesterase 10A, Ensembl gene identifier ENSG00000112541).