Orbitofrontal encoding regret

You won’t regret reading this

Gregory B Bissonette, Daniel W Bryden, & Matthew R Roesch (based on Steiner & Redish, 2014),
Nature Neuroscience, volume 17, number 7, July 2014

I10-80-prefrontalThe orbitofrontal cortex and ventral striatum encode expected outcomes during decision taking. Activity in these brain regions also reflects the perception of missed opportunities. Neural signals related to regret at missed opportunities are encoded here.

In a recent experiment, rats had to pass through four food-reward zones. Once in a reward zone, the pitch of an acoustic tone informed the rat how long it would have to wait for the reward. The rat had to weigh-up the value of the reward against the cost of waiting for the reward (cost-benefit analysis). This happened at each zone that it passed through. The rat had to decide whether to stay, and wait for the reward, or move to the next zone. Sometimes the decision to move on to the next zone did not work out for the rat, with the next zone giving an even worse reward/time relationship than the previous zone.

When rats discovered that they had made a bad decision in this way, they turned their heads and looked back at the previous zone. Scanning suggests that this looking-back is neurally encoded in the orbitofrontal and the ventral striatum. The rats are suggested to be thinking about the reward they have passed up because their neural activity is similar to their activity when they considered the original reward. The neurons in these areas were found to encode activity for each of the four reward zones. Those neurons that encode, for instance, for cherries as a food-reward are highly active when the rat enters a cherry-reward zone. This activity can be decoded both at the level of single-cells and over the ensemble of neurons in the orbitofrontal.

nrn2672-f2When the rat was looking back, the orbitofrontal and ventral striatum encoded the foregone reward, not the possible current reward. Similarly, other studies show that the orbitofrontal and other prefrontal areas can encode for imagined or possible future outcomes. This suggests the orbitofrontal is important for thinking about both past and future decisions. This experiment was performed with rats, but humans with orbitofrontal damage have problems with experiencing regret for decisions, and corresponding problems in anticipating the negative consequences of future actions.



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