Compounds of formula (I) ##STR00001## wherein A and B are amine-substituted sidechains, Y.sup.1 and Y.sup.2 form various tricyclic cores, X.sup.a and X.sup.b are C, CH, or N, as defined herein, and R.sup.x is an optional substituent. Compounds and compositions of formula (I) are contemplated as well as methods for treating conditions or disorders prevented by or ameliorated by .alpha.7nAChR ligands that encompass compounds of formula (I) and other tricyclic derivatives. Methods of using amino-substituted tricyclic derivatives also are described herein.