A study by Elliott and colleagues (2003), published in The Journal of Neuroscience, used a functional magnetic resonance imaging technique (fMRI) to identify the brain areas that are affected by rewards. The parametric technique is a way of investigating how the brain becomes activated when it is exposed to the reinforcement of money.
The study examined both the relative (the actual reward) and the absolute reward (the estimated worth of a reward). It seems that financial reinforcement (money) is affecting the brain in the same way as primary reinforcers (food/sex etc.) do.
Even abstract rewards (symbolic rewards in a fictitious competition) are associated with neuronal responses in the same brain regions that respond to primary reinforcers.
One of the advantages with measuring money is that is quantifiable, which makes it possible to investigate whether the amount of money, and not just money itself, has an impact on the reinforcement mechanisms as well.
The volunteers did a rewarded target detection task, and they received a financial reward when they answered correctly on the detection task. The value of the reward varied between every task so that it was possible to measure how different amounts of rewards would affect the brain.
The following three brain structures were involved in the presence and occurrence of rewards, regardless of reward value: amygdala, striatrum, the dopaminergic midbrain. The dopaminergic midbrain (the brain’s reward system) is involved in reinforcement, and the amygdala is involved in the processing of emotions.
Another interesting finding is that the premotor cortex shows a linear relationship with increasing reward value. This might reflect a (motor) preparedness to respond to larger rewards as we want to be motorically prepared to obtain a large reward.
Also, activity of the orbitofrontal cortex was associated with the coding of relative, rather than absolute, values of rewards.
Taken together, it seems that there is an observable association between money and the activation of brain regions that are involved in reinforcement mechanisms and reward. This might explain why money is addictive, and why gambling is so addictive as well.
At last, it seems that three distinct areas of the brain are manipulated by: (a) the presence of a reward, (b) the value of a reward, (c) the processing of relative and absolute reward values.