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Two distinct brain regions have independent influence on decision-making

Often when we make a decision, we calculate its “expected value,” by multiplying the value of something (how much we want or need it) with the probability that we might be able to obtain it, a concept first introduced by 17th-century mathematician Blaise Pascal.

Now, research conducted at the Icahn School of Medicine at Mount Sinai and published in the journal Neuron is showing for the first time in monkeys which parts of the brain are involved in the two-pronged decision-making process that determines this expected value.

“For a long time, we thought that representations of value and probability were being evaluated in the same, single part of the brain,” says Peter Rudebeck, PhD, Assistant Professor of Neuroscience and Psychiatry at the Icahn School of Medicine at Mount Sinai and lead author of the new study. “What’s exciting here is that we’re showing that it’s being done in two different parts of the brain, which are separate both functionally and anatomically.”

Mount Sinai researchers focused on two areas of the brain, the orbital frontal cortex (OFC) and the ventrolateral prefrontal cortex (VLPFC). While previous research has indicated that people whose OFC was damaged by injury or disease have impaired decision-making abilities, little was previously known about their precise roles in the decision-making process.

“Depression and anxiety disorders are characterized by changes in the way that people process rewards and make decisions. In some cases, changes in decision-making can be so extreme that individuals are unable to lead normal lives,” says Dr. Rudebeck. “Determining which parts of the brain help us to make decisions based on the subjective value and probability is therefore a critical step in understanding how these debilitating disorders are caused.”