Neurochemical Systems and Signaling

The human brain is made up of billions of neurons that communicate with each other through chemical messengers, which are referred to as neuroactive substances. These neuroactive substances include neurotransmitters, neuromodulators, and neurohormones. Some neurotransmitters also act as neuromodulators and neurohormones. It is unlikely that there would ever be a consensus about the meanings of these neuroactive substances, including neurotransmitters, since the term ‘neurotransmitter’ has tradit