To facilitate the selection of appropriate foods, the taste system must be able to determine both the identity and the hedonic value (or valence) of taste cues; however, the circuits that encode these features of taste cues and drive downstream behaviours are unclear. Wang et al. traced the projections of primary gustatory cortex neurons in mice and found that those originating in sweet- and bitter-responsive fields project to the basolateral amygdala (BLA) and central amygdala (CEA), respectively. Optogenetic stimulation of these amygdala subfields showed that they can confer valence to a neutral taste stimulus or transform the hedonic responses to otherwise appetitive or aversive taste stimuli. Silencing amygdala neurons disrupted valence coding without affecting the animals’ ability to identify and discriminate between tastants. Thus, the cortex and amygdala function independently to represent taste identity and valence.
Wang, L. et al. The coding of valence and identity in the mammalian taste system. Nature 558, 127–131 (2018)
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Whalley, K. A matter of taste. Nat Rev Neurosci 19, 444 (2018). https://doi.org/10.1038/s41583-018-0035-y