Choosy cortex

brainmaps.org

C. Padoa-Schioppa & J.A. Assad, "Neurons in the orbitofrontal cortex encode economic value," Nature, 441:223-6, 2006. (Cited in 76 papers)

Researchers from Harvard Medical School measured neuronal firing rates in macaques who had been offered different juice rewards. By varying the amounts and types of juice in separate trials the researchers gauged subjective preference for the juices, finding that certain neurons in the orbitofrontal cortex (OFC) only fired for one juice type, while others fired for either juice.

"Now that you know that these neurons exist," says Veit Stuphorn from Johns Hopkins University, "you can compare very different sensory stimuli that also might be [subjectively] rewarding," such as water or photos of female monkeys in estrous.

The researchers used a statistical tool for this study called econometrics, which helped them identify what a given neuron responded to: juice taste, the chosen juice, or either of two offered juices. They have since shown that if a neuron represents the subjective value of one juice, it does not depend on what other juice options are available at the same time (Nat Neurosci, 11:95-102, 2008).

Study co-author Camillo Padoa-Schioppa, now at Washington University in St. Louis, says his group is working with macaques, varying juice quantity and the specific contexts in which they are presented. Some neurons may be able to slow or speed firing, he says, depending on the situation, to change their sensitivity to the amount of juice.