This includes: (a) the ability of D-isoleucine to stimulate D-serine release without adding to cognitive decline, (b) the discovery of D-leucine as an anti-seizure agent, (c) the ability of D-threonine to potentiate currents within the hippocampus, and (d) the ability of D-tyrosine to inhibit tyrosinase. Here, TYR is linked to Mental deterioration.