Excitotoxins are a special group of neurotoxic substances that excite somatic and dendritic receptors in such a way that the neurons may die. All excitotoxins are in principle agonists of glutamate receptors in the brain and are structurally related to glutamate. The excitotoxins can be administered systemically before the blood brain barrier is fully developed (at day 10 in rats) or they can be injected locally into the brain. In the latter case, they produce the so called axonsparing/dendrito somatic lesions.