How do we know if it was worth the wait in line to get a meal at the new restaurant in town? To do this our brain must be able to signal how good the meal tastes and associate this feeling with the restaurant. This is done by a small group of cells deep in the brain that release the chemical dopamine.
The amount of dopamine released by these cells can influence our decisions by telling us how good a reward will be in the future. For example, more dopamine is released to the smell of a cake baking relative to the smell of leftovers. But does waiting change how dopamine is released?
A new study in Cell Reports sheds light on how dopamine cells in the brain signal the passage of time. The study used a technique called voltammetry to record dopamine release in rodents trained using Pavlovian conditioning. This task used two different tones that both predicted the delivery of a food reward. One tone was presented only after a short wait while the other tone was presented only after a long wait. Researchers found that more dopamine was released to the short wait tone. These results highlight that when dopamine neurons respond to cues, faster is better.
Differences in the dopamine response between short wait and long wait cues were evident even when these cues were never experienced together within the same context. Conditioned responding updated accordingly with a change in cue-evoked dopamine release but was unrelated to a difference in the dopamine response between cues.
"The big question that we're focusing on is to identify the brain signals that influence the decisions we make," senior author said. "Many decisions are based upon comparing the value between cues associated with different rewards. There is a lot of evidence to suggest that these dopamine signals and external cues provide useful value-related signals that could inform our decisions to engage in a behavior."
While the researchers are interested in studying how dopamine release is involved with cues triggering behavior, their work could also inform the understanding of drug addiction, which is closely intertwined with dopamine. Drug addiction can "hijack" the brain regions where dopamine is released. "By figuring out how the dopamine system works in normal and abnormal circumstances, we could potentially identify important changes and the ways that could target the dopamine system to rectify the consequences of those behaviors," author said.
How dopamine tells you it isn't worth the wait
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