Final answer:
The post-synaptic membranes of individuals not dependent on drugs typically have higher numbers of dopamine receptors compared to those who are addicted, as illustrated by PET scan studies showing more dopamine binding in non-addicted brains.
Step-by-step explanation:
The number of dopamine receptors in the post-synaptic membrane of an individual who is not dependent on drugs is usually higher compared to those who are addicted. This is supported by the observation that non-addicted individuals exhibit more binding to dopamine receptors in the brain, implying a larger number of receptors, whereas addicted individuals show less binding, which indicates fewer receptors.
Various studies and analyses have highlighted the impact of controlled stimulations, such as drug administration, on the number of dopamine molecules. For example, PET scans depicted in studies show differential dopamine binding in brains between normal and addicted individuals. These insights, along with the measurable changes in the number of dopamine molecules stored in vesicles after exposure to different drugs, help infer the change in the number of receptors and neurotransmitter release in relation to drug dependence.