Fig. 1. Biological and bio-inspired gustatory systems for feeding.

a A simplified abstraction of the biological gustatory pathway for feeding. Taste receptors in the tongue generate electrical responses to food stimulants based on the chemical composition of the food, which is conveyed to both the hunger neuron and the appetite neuron, representing the physiological and psychological state of the body. The output from these neurons is subsequently evaluated by a cortical circuit, which makes the decision for feeding. b A bio-inspired gustatory system for making feeding decisions by exploiting heterogeneous integration of graphene chemitransistor-based “electronic tongue” for sensing and encoding taste stimulants and monolayer MoS₂ memtransistor-based “electronic gustatory cortex” for adaptive (in-memory) cortical computing. Additionally, the non-volatile and analog programmability of MoS₂ memtransistors allows for the adjustment of hunger and appetite thresholds, which is necessary to capture the adaptive feeding behavior.