neurotransmitter norepinephrines molecular level neurotransmitter called GABA GABA, a neurotransmitter GABA as a neurotransmitter GABA involved in mood GABA neurotransmitter neurotransmitter major neurotransmitters GABA contributes GABA regulating anxiety The Brain from Top to Bottom: Neurotransmitters neurotransmitters GABA neurotransmitters neurotransmitter