“Expected value” is computed by multiplying the value of something (how much we want or need it) by the probability that we might be able to obtain it. The concept, introduced by 17th-century mathematician Blaise Pascal, is a mainstay of our decisionmaking processes. Researchers at Icahn School of Medicine at Mount Sinai examined monkeys to see which parts of the brain are involved in this decision-making process and find that it is being done in two different parts of the brain, the orbital frontal cortex (OFC) and the ventrolateral prefrontal cortex (VLPFC). These two parts of the brain are highly interconnected, with previous research indicating that both send connections to another area of the frontal lobe called the ventromedial prefrontal cortex (VMPFC), and functional magnetic resonance imaging suggestng that the VMPFC may be where choices ultimately get made. The investigators tested whether the VMPFC is involved in comparing different values in a separate set of experiments, where they induced lesions in that area. The monkeys were able to make a decision based on probability or value alone, but when they had to compare values, they were less able to do that. This is consistent with human data showing that people who have brain damage in that area also have trouble with making decisions. Researchers hope their research will aid in the development of treatment interventions for the many people who suffer from depression and anxiety.