Methods for increasing D-Serine concentration and reducing concentration of the toxic products of D-Serine oxidation, for enhancing learning, memory and/or cognition, or for treating schizophrenia, Alzheimer's disease, ataxia or neuropathic pain, or preventing loss in neuronal function characteristic of neurodegenerative diseases involve administering to a subject in need of treatment a therapeutically effective amount of a compound of formula I, or a pharmaceutically acceptable salt or solvate thereof: wherein R1 and R2 are independently selected from hydrogen, halo, nitro, alkyl, acyl, alkylaryl, and XYR5; or R1 and R2, taken together, form a 5, 6, 7 or 8-membered substituted or unsubstituted carbocyclic or heterocyclic group; X and Y are independently selected from O, S, NH, and (CR6R7)n; R3 is hydrogen, alkyl or M+; M is aluminum, calcium, lithium, magnesium, potassium, sodium, zinc ion or a mixture thereof; Z is N or CR4; R4 is from selected from hydrogen, halo, nitro, alkyl, alkylaryl, and XYR5; R5 is selected from aryl, substituted aryl, heteroaryl and substituted heteroaryl; R6 and R7 are independently selected from hydrogen and alkyl; n is an integer from 1 to 6; at least one of R1, R2 and R4 is other than hydrogen; and at least one of X and Y is (CR6R7)n. D-serine or cycloserine may be coadministered along with the compound of formula I.