Final answer:
The PET scan study found that normal-weight individuals have higher levels of dopamine receptors compared to obese individuals, indicating a difference in the brain's reward system potentially contributing to obesity.
Step-by-step explanation:
The PET scan study comparing normal-weight and obese individuals with regard to dopamine receptors found that normal-weight individuals had higher levels of dopamine receptors. This suggests that obese individuals may have fewer dopamine receptors, which aligns with the findings in studies of individuals with addiction, where it has been observed that addicted persons show less binding to dopamine receptors. Dopamine plays a crucial role in the brain's reward system, and its action contributes significantly to behavior patterns in addiction, obesity, and other psychiatric conditions.