ABSTRACT
Positron Emission Tomography (PET) is an imaging modality that uses radiotracers to measure receptor levels in the brain. The dopamine system is closely associated with modulating motivated, reward-driven behavior and it is also directly implicated in addiction. The brain’s dopamine system originates in the midbrain, with the dopamine neuron cell bodies located in the substantia nigra and ventral tegmental area. Cocaine blocks the re-uptake of dopamine, and increases dopamine levels, but it is not selective for dopamine. The most studied addiction using PET imaging is cocaine use disorder, and many of these studies have focused on imaging the D2 receptor and dopamine release. Imaging studies in humans as well as animal models have helped in understanding the neurobiological effects of cocaine and identify substrates of cocaine, and by proxy, other addictions. Cocaine use induces a massive increase in extracellular dopamine in the mesoaccumbens and nigrostriatal pathways, an effect that is likely to enhance the rewarding properties of cocaine.
