Dopamine is then chemically converted to norepinephrine. This chemical process is outlined simply in the following figure. Dopamine can have either an excitatory or inhibitory effect on the postsynaptic potential. In other words, when dopamine leaves the presynaptic neuron and goes into the synapse, it can then bind to receptors on the postsynaptic neuron. After dopamine is bound to the postsynaptic cell, it can either facilitate an action potential or inhibit it.
Neurotransmitters are the messengers within the central nervous system.
They are responsible for communicating with other neurons either through chemical or electrical signals. A neuron that classically releases dopamine is called a dopaminergic neuron. A series of neurons that are connected by synapses forms a pathway called a dopaminergic pathway. This system is concerned with the intiation and maintenance of motor behaviors. The striatum and the Substantia Nigra are both key players in a group of structures called the basal ganglia.