a chemical substance, a neurotransmitter, found in the brain that regulates movement, balance, and walking.
Biology Dictionary
Definition:
A hormonelike substance with the chemical formula C8H11NO2. It is found in the nervous system as an important neurotransmitter, or substance which transmits nerve signals from neuron to neuron. It is also an intermediate in the productions of the hormones epinephrine and norepinephrine.