<qa>  What is the name of the major excitatory neurotransmitters in the central nervous systemGlutamate and aspartate have been identified as the major excitatory neurotransmitters in the central nervous system. A massive increase in the release of these excitatory amino acids EEA has been described following traumatic brain injury. The resulting overstimulation of neuronal EAA receptors, particularly the N-Methyl-D-Aspartate NMDA receptors, leads to excessive influx of calcium through receptor gated ion-channels, causing metabolic derangement and finally cell death. Although the exact role of EEA in patients who have suffered severe head injury remains to be established, it has been shown that sustained high intracranial pressure ICP and poor outcome are significantly correlated to high levels of EEA using microdialysis. Disadvantages of microdialysis are that it can only be used to evaluate a limited part of the brain and that it can only be applied in the acute phase following injury. The same limits also apply to ICP measurements. Therefore, methods which evaluate both the extent and time course of damage in vivo are urgently needed. 