The phrase "certain brain chemicals" refers to neurotransmitters, which are substances that transmit signals across a synapse from one nerve cell (neuron) to another. Full definition
The brains of people with the schizophrenia show various abnormalities, including faulty neural connections or an imbalance of certain brain chemicals. (sciencedaily.com)
The monthly fluctuation of estrogen and progesterone (and other hormones like FSH and LH) largely controls a woman's cycle and there are theories that these hormones can interact with certain brain chemicals, creating real symptoms during these times. (wellnessmama.com)
It is thought that one component, californidine, acts on the central nervous system to promote sleep, while others, including protopine, cryptopine and allocryptopine, enhance certain brain chemicals that inhibit nerve impulses, resulting in a calming effect on the brain, peripheral nerves and muscles. (orangenaturals.com)