Aspartate and glutamate are both potentially excitotoxic amino acids. Aspartame is made up of aspartic acid (aspartate), phenylalanine, and methyl alcohol (methanol). Heat breaks Aspartame down into the component parts. Furthermore, the body breaks methyl alcohol down into formaldehyde and formic acid. The best book I've found thus far on excitotoxins in general is, _Excitotoxins: The taste that kills_, by Russell Blaylock. If you're interested in reading the scientific literature run a PubMed search on John W Olney. The major sources for excitotoxins in the American diet are Aspartame and MSG (and other food additives high in free glutamate), and Olney does a great job of proving how excitotoxins damage the brain. The whole excitotoxin story is a frightening example of how the food and drug industry can obscure good scientific results.