Dopamine pathway links food flavour to nutrients in mice

A study in Nature describes a dopamine (DA) pathway that lets animals learn the nutrient content of food. The nutrient content of food is first estimated in the mouth as flavour. It is then measured again through slower signals from the gut. How the two signals are integrated to drive learning was unclear, and the authors identify the circuit responsible doi.org.

Dopamine release in the basolateral amygdala

The authors showed that DA neurons in the ventral tegmental area are necessary for associating nutrients with flavours. Post-ingestive nutrients trigger DA release selectively in a small region of the anterior basolateral amygdala (BLA). No such release was seen in the canonical DA targets in the striatum doi.org.

In mice, this nutrient-triggered release occurs preferentially in the left BLA. According to the authors, the same structure is preferentially activated by post-ingestive nutrients in humans doi.org.

The team also identified the gut sensors responsible for the nutrient-triggered DA release. These sensors activate BLA-projecting DA neurons that are defined by expression of cholecystokinin doi.org.

Behavioural tests and neuron imaging

Stimulating DA axon terminals in the anterior BLA drove flavour–nutrient learning. It did not affect other aspects of feeding behaviour, which points to a specific role of this pathway in the learning itself doi.org.

Two-photon imaging of neurons in the left anterior BLA showed that they integrate gustatory and post-ingestive cues. Silencing these neurons prevented flavour–nutrient learning doi.org.

The experiments on the circuit were done in mice, and the human data concern activation of the same brain structure by post-ingestive nutrients. Based on these results, the authors conclude that they have established a neural basis for how animals learn about the nutrient content of their food doi.org.

Dopamine pathway to the left amygdala links food flavour to nutrient content in mice

Dopamine release in the basolateral amygdala

Behavioural tests and neuron imaging

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