The neurons are responsible for the trnasmission of signals in the
brain. the drugs like narcotis interfere with the neurons and
effect the process of transimitting signals. they can activate
nuerons beacuse of their chemical structure mimics that of a
natural neurotransmittor which helps them to attach to the neurons
and activate them. They are also capable of releasing abnormally
large amounts of neural transmitters or prevent recycling of these
brain chemicals by interfering with transporters, this can disrupt
the normal communication between neurons.
The other parts of the brain which are affected by the drug
addiction include the basal ganglia, which is responsible for the
motivation and other healthy activities, and the extended amygdala,
which is responsible for stressful feelings like anxiety,
irritability. and the prefrontal cortex, which is responsible to
think, make decisions and exert self control.