Glutamate:

Glutamate is an amino acid that’s the most abundant excitatory neurotransmitter in the central nervous system (CNS), carrying signals between neurons, attaching itself to new cells by binding onto NMDA receptors (N-methyl-D-aspartate). Glutamate passes calcium into cells, carrying electrical or chemical signals important for learning, memory, and other cognitive functions. It’s also found in foods (cheese, tomatoes, soy sauce), though excessive consumption leads to headache, nausea, and flushing (MSG in Chinese restaurants). Glutamate is involved in: learning and memory, cognition, movement control, sensory perception, and mood regulation