By studying animals choosing between two drink options, researchers have discovered that the activity of specific neurons in the brain leads directly to choosing one option over another. The findings could lead to a better understanding of how decision-making goes wrong in addiction and depression conditions. The findings of the study are published in the journal Nature.
When you are faced with a choice, say, whether to have ice cream or chocolate cake for dessert, sets of brain cells just above your eyes fire as you weigh your options. Animal studies have shown that each option activates a distinct set of neurons in the brain. The more enticing the offer, the faster the corresponding neurons fire.
In a new experiment, researchers let animals choose between different juice flavors. By changing the neurons' activity, the researchers changed how appealing the monkeys found each option, leading them to make different choices.
In another experiment, the monkeys saw the first option, then the other, before choosing. Delivering a higher current while the monkey was considering one option disrupted the computation of value taking place at that time, making the monkey more likely to choose whichever option was not disrupted. This result indicates that values computed in the orbitofrontal cortex are a necessary part of making a choice.
"When it comes to this kind of choice, the monkey brain and the human brain appear very similar," Padoa-Schioppa said. "We think that this same neural circuit underlies all sorts of choices people make, such as between different dishes on a restaurant menu, financial investments, or candidates in an election. Even major life decisions like which career to choose or whom to marry probably utilize this circuit. Every time a choice is based on subjective preferences, this neural circuit is responsible for it."