Where in the brain do neurotransmitters have their effects?

Neurotransmitters are chemicals in your brain that pass along information from one cell to another. Neurotransmitters act in the synapse, the space between two brain cells (neurons). Neurotransmitters released by presynaptic neurons act on receptors on postsynaptic neurons (Figure 3). The amount of neurotransmitter in the synaptic space and the sensitivity of the postsynaptic cell receptors determine the neurotransmitter’s effect on the postsynaptic brain cell.

There are many different neurotransmitters. Although dopamine is probably the neurotransmitter that is maximally involved in ADHD, norepinephrine and serotonin probably play lesser roles. The relative balance among these neurotransmitters may be as important as their absolute amounts. Dopamine is the main neurotransmitter in the striatum, while norepinephrine is the main neurotransmitter in the frontal lobe.