Neuroeconomics is the study of how we make decisions using brain activity (neuroscience), economics and psychology. Think of it as the behavioral finance of our intuition and reactions. Multiple studies have shown how our brains react to different forms of stimulus (mostly gains and losses). For example:

The brain activity of a person that’s making money on their investments is indistinguishable from a person who is high on cocaine or morphine. The brain of a cocaine addict who is expecting to get a fix and people who are expecting to make a profitable financial gamble are virtually the same. This explains why we tend to get overconfident and greedy with our investments. We want more, more, more because of the rush.