Gustatory Signal Processing in Mammalian Systems

Gustatory signal processing in mammals encompasses a cascade of events beginning with the molecular recognition of tastants by specialised epithelial cells in the oral cavity and concluding with the integration of taste signals in higher brain centres that guide feeding behaviours. Taste receptor cells (TRCs) within taste buds detect five basic modalities—sweet, sour, salty, bitter and umami—via G protein-coupled receptors or ion channels. These receptor events elicit intracellular calcium transients and trigger the release of neurotransmitters such as ATP through dedicated channels. Afferent fibres then transmit the encoded information to the nucleus of the solitary tract in the brainstem, where initial integration occurs before relaying to the thalamus and gustatory cortex. Parallel circuits involving the amygdala and hypothalamus integrate taste with emotional valence and homeostatic state. Plasticity within these pathways underlies short-term taste memory, aversive or appetitive learning from postingestive consequences and the capacity for regeneration following injury. Recent advances have illuminated receptor structures, ion-channel mechanisms and central coding strategies, underscoring the complexity and adaptability of the gustatory system in regulating food choice, nutrition and health.

Research from Nature Portfolio

Recent studies have shown that delayed postingestive feedback can reactivate neural representations of novel flavours in the amygdala, thereby solving the problem of temporal credit assignment in aversive learning. Optogenetic stimulation of malaise-coding hindbrain neurons during delay periods selectively reinstates flavour-specific activity patterns, strengthening memory retrieval and stabilising population codes for those flavours. In parallel, investigations into proton-selective ion channels have revealed that OTOP1, expressed in sour (Type III) TRCs, acts as a sensor for ammonium chloride. Mutation of a key arginine residue in OTOP1 selectively attenuates responses to ammonium while preserving acid sensitivity. Loss-of-function models demonstrate that OTOP1 is essential for physiological and behavioural sensitivity to ammonium, expanding the repertoire of ion channels that mediate taste detection at the periphery.

Gustatory Signal Processing in Mammalian Systems publication trend

The graph below shows the total number of articles in gustatory signal processing in mammalian systems across all publications each year (not limited to Nature Index journals).

Technical terms

G protein-coupled receptor (GPCR): A cell-surface receptor that initiates intracellular signalling cascades when bound by specific ligands, such as sweet or umami tastants.

Taste receptor cell (TRC): An epithelial cell within a taste bud specialised for detecting tastants and transmitting signals to gustatory nerves.

OTOP1: A proton-selective ion channel in Type III TRCs that mediates detection of sour stimuli and ammonium chloride.

CALHM channel: Calcium homeostasis modulator proteins that form voltage-gated channels for ATP release from Type II TRCs.

Postingestive feedback: Physiological signals arising after nutrient ingestion that modify neural flavour representations and guide learning.

Persistent activity: Sustained neural firing in sensory cortex that supports short-term memory of recent stimuli.

References

1. A neural mechanism for learning from delayed postingestive feedback. Nature (2025).
2. The proton channel OTOP1 is a sensor for the taste of ammonium chloride. Nature Communications (2023).
3. The structure of human sweetness. Cell (2025).
4. A neural substrate for short-term taste memories. Neuron (2023).
5. CALHM3 Is Essential for Rapid Ion Channel-Mediated Purinergic Neurotransmission of GPCR-Mediated Tastes. Neuron (2018).