Illustration of NMDA (N-methyl-D-aspartate, left), AMPA (a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, centre) and GABA (gamma-aminobutyric acid, right) neurotransmitter receptors. NMDA and AMPA receptors are excitatory receptors that transport calcium cations (red) into neurons after being activated by the neurotransmitter glutamate. GABA receptors are inhibitory receptors that transport chloride anions (green) following activation by gamma aminobutyrate. NMDA and AMPA receptors play an important role in memory. GABA receptors act to reduce brain activity.