1,2,4-oxadiazole derivatives selected from the group consisting of N-{4-[5-(4-methoxyphenyl)-1,2,4-oxadiazol-3-yl]phenyl}pyridine-4-carboxamide, N-{4-[5-(2-chlorophenyl)-1,2,4-oxadiazol-3-yl]-3-methoxyphenyl}pyridine-2-carboxamide; N-{4-[5-(2-chloro-4-fluorophenyl)-1,2,4-oxadiazol-3-yl]-3-methoxyphenyl} pyridine-2-carboxamide; N-{3-chloro-4-[5-(2-chloro-4-fluorophenyl)-1,2,4-oxadiazol-3-yl]phenyl}pyridine-2-carboxamide; N-{4-[5-(2-chloro-4-fluorophenyl)-1,2,4-oxadiazol-3-yl]-3-fluorophenyl} pyridine-2-carboxamide; N-{4-[5-(2-methoxyphenyl)-1,2,4-oxadiazol-3-yl]-3-fluorophenyl}pyridine-2-carboxamide; N-[4-(5-phenyl-1,2,4-oxadiazol-3-yl)-3-trifluoromethyl)phenyl]pyridine-2-carboxamide; N-{4-[5-(2-chlorophenyl)-1,2,4-oxadiazol-3-yl]-3-(trifluoromethyl)phenyl} pyridine-2-carboxamide; N-[3-methyl-4-(5-phenyl-1,2,4-oxadiazol-3-yl)phenyl]pyridine-2-carboxamide; N-{4-[5-(2-chlorophenyl)-1,2,4-oxadiazol-3-yl]-3-methylphenyl}pyridine-2-carboxamide; N-{4-[5-(2-chlorophenyl)-1,2,4-oxadiazol-3-yl]-3-methoxyphenyl}-6-fluoropyridine-2-carboxamide; 5-chloro-N-{4-[5-(2-chlorophenyl)-1,2,4-oxadiazol-3-yl]-3-methoxyphenyl}-3-fluoropyridine-2-carboxamide; 6-chloro-N-{4-[5-(2-chlorophenyl)-1,2,4-oxadiazol-3-yl]-3-methoxyphenyl}pyridine-2-carboxamide N-{4-[5-(2-chlorophenyl)-1,2,4-oxadiazol-3-yl]-3-methoxyphenyl} pyrimidine-4-carboxamide N-{4-[5-(2-chlorophenyl)-1,2,4-oxadiazol-3-yl]-3-methoxyphenyl}thiophene-2-carboxamide; 6-fluoro-N-{4-[5-(2-fluorophenyl)-1,2,4-oxadiazol-3-yl]-3-methoxyphenyl} pyridine-2-carboxamide; 3,6-dichloro-N-{4-[5-(2-fluorophenyl)-1,2,4-oxadiazol-3-yl]-3-methoxy phenyl}pyridine-2-carboxamide; N-{3-chloro-4-[5-(2-chlorophenyl)-1,2,4-oxadiazol-3-yl]phenyl}-6-fluoropyridine-2-carboxamide; N-(2-chlorophenyl)-4-(5-phenyl-1,2,4-oxadiazol-3-yl)benzene-1-sulfonamide; N-(2,4-difluorophenyl)-4-[5-(pyridin-2-yl)-1,2,4-oxadiazol-3-yl]benzene-1-sulfonamide; N-[4-(3-phenyl-1,2,4-oxadiazol-5-yl)phenyl]benzamide; 3-chloro-N-[4-(3-phenyl-1,2,4-oxadiazol-5-yl)phenyl]benzamide; 4-methoxy-N-[4-(3-phenyl-1,2,4-oxadiazol-5-yl)phenyl]benzamide; 4-nitro-N-[4-(3-phenyl-1,2,4-oxadiazol-5-yl)phenyl]benzamide; 1-methyl-N-[4-(3-phenyl-1,2,4-oxadiazol-5-yl)phenyl]-1H-pyrrole-2-carboxamide; or pharmaceutically acceptable salts, hydrates or solvates thereof, for use as positive allosteric modulator ligands of metabotropic glutamate receptors of group III subtype 4 (mGluR4) in the treatment of the central nervous disorders modulated by mGluR4 receptors. N-{4-[5-(4-methoxyphenyl)-1,2,4-oxadiazol-3-yl]phenyl}pyridine-4-carboxamide, N-{4-[5-(2-chlorophenyl)-1,2,4-oxadiazol-3-yl]-3-methoxyphenyl}pyridine-2-carboxamide; N-{4-[5-(2-chloro-4-fluorophenyl)-1,2,4-oxadiazol-3-yl]-3-methoxyphenyl} pyridine-2-carboxamide; N-{3-chloro-4-[5-(2-chloro-4-fluorophenyl)-1,2,4-oxadiazol-3-yl]phenyl}pyridine-2-carboxamide; N-{4-[5-(2-chloro-4-fluorophenyl)-1,2,4-oxadiazol-3-yl]-3-fluorophenyl} pyridine-2-carboxamide; N-{4-[5-(2-methoxyphenyl)-1,2,4-oxadiazol-3-yl]-3-fluorophenyl}pyridine-2-carboxamide; N-[4-(5-phenyl-1,2,4-oxadiazol-3-yl)-3-trifluoromethyl)phenyl]pyridine-2-carboxamide; N-{4-[5-(2-chlorophenyl)-1,2,4-oxadiazol-3-yl]-3-(trifluoromethyl)phenyl} pyridine-2-carboxamide; N-[3-methyl-4-(5-phenyl-1,2,4-oxadiazol-3-yl)phenyl]pyridine-2-carboxamide; N-{4-[5-(2-chlorophenyl)-1,2,4-oxadiazol-3-yl]-3-methylphenyl}pyridine-2-carboxamide; N-{4-[5-(2-chlorophenyl)-1,2,4-oxadiazol-3-yl]-3-methoxyphenyl}-6-fluoropyridine-2-carboxamide; 5-chloro-N-{4-[5-(2-chlorophenyl)-1,2,4-oxadiazol-3-yl]-3-methoxyphenyl}-3-fluoropyridine-2-carboxamide; 6-chloro-N-{4-[5-(2-chlorophenyl)-1,2,4-oxadiazol-3-yl]-3-methoxyphenyl}pyridine-2-carboxamide N-{4-[5-(2-chlorophenyl)-1,2,4-oxadiazol-3-yl]-3-methoxyphenyl} pyrimidine-4-carboxamide N-{4-[5-(2-chlorophenyl)-1,2,4-oxadiazol-3-yl]-3-methoxyphenyl}thiophene-2-carboxamide; 6-fluoro-N-{4-[5-(2-fluorophenyl)-1,2,4-oxadiazol-3-yl]-3-methoxyphenyl} pyridine-2-carboxamide; 3,6-dichloro-N-{4-[5-(2-fluorophenyl)-1,2,4-oxadiazol-3-yl]-3-methoxy phenyl}pyridine-2-carboxamide; N-{3-chloro-4-[5-(2-chlorophenyl)-1,2,4-oxadiazol-3-yl]phenyl}-6-fluoropyridine-2-carboxamide; N-(2-chlorophenyl)-4-(5-phenyl-1,2,4-oxadiazol-3-yl)benzene-1-sulfonamide; N-(2,4-difluorophenyl)-4-[5-(pyridin-2-yl)-1,2,4-oxadiazol-3-yl]benzene-1-sulfonamide; N-[4-(3-phenyl-1,2,4-oxadiazol-5-yl)phenyl]benzamide; 3-chloro-N-[4-(3-phenyl-1,2,4-oxadiazol-5-yl)phenyl]benzamide; 4-methoxy-N-[4-(3-phenyl-1,2,4-oxadiazol-5-yl)phenyl]benzamide; 4-nitro-N-[4-(3-phenyl-1,2,4-oxadiazol-5-yl)phenyl]benzamide; 1-methyl-N-[4-(3-phenyl-1,2,4-oxadiazol-5-yl)phenyl]-1H-pyrrole-2-carboxamide; or pharmaceutically acceptable salts, hydrates or solvates thereof, for use as positive allosteric modulator ligands of metabotropic glutamate receptors of group III subtype 4 (mGluR4) in the treatment of the central nervous disorders modulated by mGluR4 receptors.