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:whereinR1 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; andat least one of X and Y is (CR6R7)n.D-serine or cycloserine may be coadministered along with the compound of formula I.