The present invention discloses a compound of formula I, or a pharmaceutically acceptable salt thereof: (I) wherein --U--V-- represents --CH.dbd.CH--, or --CH.sub.2--CH.sub.2--, --N.dbd.CH-- or --CH.dbd.N--; X.sup.1 represents hydrogen, halogen, C.sub.1-6 alkyl, trifluoromethyl or C.sub.1-6 alkoxy; X.sup.2 represents hydrogen or halogen; Y represents a chemical bond, an oxygen atom, or a --NH-- or --OCH.sub.2-- linkage; Z represents an optionally substituted aryl or heteroaryl group; R.sub.1 represents hydrocarbon, a heterocyclic group, trifluoromethyl, --SO.sub.2R.sup.a, --SO.sub.2NR.sup.aR.sup.b, --COR.sup.a, --CO.sub.2R.sup.a or --CONR.sup.aR.sup.b; and R.sup.a and R.sup.b independently represent hydrogen, hydrocarbon or a heterocyclic group; pharmaceutical compositions comprising it; its use in methods of treatment; use of it in the manufacture of a medicament for treating and/or preventing anxiety; convulsions or a cognitive disorder; and methods of treatment using it. ##STR00001##