The dorsal anterior cingulate cortex (dACC) is crucial for reinforcement learning and decision-making. However, the excitatory and inhibitory mechanisms underlying these functions, governed by glutamate and GABA, are not properly understood. We used 1H-MRS to probe glutamate and GABA in the dACC during a task comprised of three conditions: discrimination, uncertainty and a null condition. A preference to higher gain option during the discrimination condition was reflected by elevated GABA levels during the uncertainty condition compared to the discrimination condition. Elevated GABA levels during the null condition predicted better behavioral-acquisition. These results indicate dACC involvement during learning of high load cognitive situation.