Chapter 3 - Chemical Neurotransmission

Abstract

As in the rest of the neocortex, there are three major categories of excitatory neurotransmitters and receptors in the prefrontal cortex: glutamate, monoamines, and acetylcholine. The essential monoamines are norepinephrine, dopamine, and serotonin. All excitatory neurotransmitters activate cognitive prefrontal functions. Norepinephrine and dopamine commonly produce inverted-U dose-related effects, with detrimental effects on cognition at high doses. Some neuropeptides have general excitatory functions by modulating norepinephrine and dopamine. γ-Aminobutyric acid (GABA) is the most prevalent inhibitory neurotransmitter. In the attention deficit/hyperactivity disorder of childhood, there is a deficit in tyrosine hydroxylase expression leading to a dopamine imbalance and secondary GABA deficit in orbitofrontal cortex. Schizophrenia is accompanied by cortical and striatal connectivity imbalance in several neurotransmitter and receptor systems, notably dopamine and GABA. Depression affects prefrontal serotonin. Parkinson’s disease is characterized by a dopamine deficit in the basal ganglia, secondarily affecting prefrontal cortex. Dementia commonly affects cholinergic and monoaminergic systems.