Glutamate is also a neurotransmitter with an excitatory (rather than inhibitory) effect on the Central Nervous System. This, rather than the placebo effect as some claim, is probably what accounts for Chinese Restaurant Syndrome after consuming high levels of Monosodium Glutamate. (Incidentally, high levels of the neurotransmitter dopamine are known to cause psychosis and symptoms of schizophrenia).

Glutamate is the neurotransmitter released by the hair cells of the inner ear responsible for detection of sound. Caffeine acts as a stimulant by suppressing levels of adenosine in the brain, which in turn increases the levels of glutamate.