Cell
Volume 184, Issue 1, 7 January 2021, Pages 257-271.e16
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Article
Top-Down Control of Sweet and Bitter Taste in the Mammalian Brain

https://doi.org/10.1016/j.cell.2020.12.014Get rights and content
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Highlights

  • Sweet and bitter are represented in the brainstem by genetically distinct neurons

  • SST+ and CALB2+ neurons in the brainstem carry bitter and sweet signals to the cortex

  • Feedback from bitter cortex amplifies bitter but suppresses incoming sweet taste signals

  • Cortical feedback via amygdala ensures bitter-evoked behavioral aversion remains robust

Summary

Hardwired circuits encoding innate responses have emerged as an essential feature of the mammalian brain. Sweet and bitter evoke opposing predetermined behaviors. Sweet drives appetitive responses and consumption of energy-rich food sources, whereas bitter prevents ingestion of toxic chemicals. Here we identified and characterized the neurons in the brainstem that transmit sweet and bitter signals from the tongue to the cortex. Next we examined how the brain modulates this hardwired circuit to control taste behaviors. We dissect the basis for bitter-evoked suppression of sweet taste and show that the taste cortex and amygdala exert strong positive and negative feedback onto incoming bitter and sweet signals in the brainstem. Finally we demonstrate that blocking the feedback markedly alters responses to ethologically relevant taste stimuli. These results illustrate how hardwired circuits can be finely regulated by top-down control and reveal the neural basis of an indispensable behavioral response for all animals.

Keywords

taste
feeding
cortex
feedback
inhibition
suppression
sweet
bitter
amygdala
behavior

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2

These authors contributed equally

3

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