The present invention relates to the (S)-enantiomer of the chemical compound having the general formula (I):wherein R1 and R2 are, equal or independently, aryl, heteroaryl, fused aryl, fused heteroaryl, mono or multi-substituted aryl, mono or multi-substituted heteroaryl, mono or multi-substituted fused aryl, mono or multi-substituted fused heteroaryl； and RTA is a 2-1,3-, or 4-1,3- or 5-1,3-thiazole ring with the general Formula (IIa), which can also be substituted.The invention also relates to said compound according to formula (I) for use in improving motivation and/or cognitive functions and/or for use in improving the reference memory in human individuals.
