The invention includes a compound of formula I: wherein R1, Y, A, n, R4 and Z have any of the values described herein, as well as salts of such compounds, compositions comprising such compounds, and therapeutic methods that comprise the administration of such compounds. The compounds are inhibitors of PDE4 function and are useful for improving cognitive function and/or treating cognitive disorders or impairment, traumatic and/or ischemic injuries of the central and peripheral nervous system and/or psychiatric disorders in animals, especially humans.