How is the "multiple identities" of dopamine achieved in "Nature Neuroscience"?

Among the neurotransmitters in the brain, dopamine has acquired an almost mysterious status

Unraveling the various functions of dopamine has always been a challenge, partly because the advanced brains of humans and other mammals contain different types of dopamine neurons, all of which are embedded in highly complex circuits

Like humans, the dopamine neurons in fruit flies provide learning signals that help them associate specific odors with specific results

"There seems to be a close connection between learning and motivation.

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Odor is important to fruit flies

But Ruta and her colleagues have noticed that dopamine continues to signal even when there is no reward

To find out, the team developed a virtual reality system in which fruit flies can navigate in an olfactory environment and walk on a treadmill-like ball, while their brain activity is monitored by an overhead microscope

Using this system, researchers can examine the brain activity of fruit flies under different conditions

When the researchers inhibited the activity of dopamine neurons, the animals' tracking of odors was reduced, and even when they were hungry, they would be more interested in food-related odors

Together, these findings reveal how the dopamine pathway performs two functions: it delivers stimulus signals to quickly shape ongoing behaviors, and at the same time provides guiding signals to guide future behaviors through learning

The next step is to understand how other neurons know what a dopamine burst means at any given time

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