Stimulus Temperature Modulates the Psychophysical Dimensions of Salt Taste

Temperature is a fundamental yet understudied parameter of gustatory experience. In this study, we designed a set of experiments that examined how stimulus temperature affects the motivational and sensory-discriminative properties of sodium (NaCl) and non-sodium (KCl) salts. In brief-access tests, water-deprived mice consistently preferred cool (14 °C) over warm (36 °C) stimuli regardless of salt content. Progressive ratio tests confirmed cool stimuli possess greater appetitive efficacy, suggesting that, under our experimental conditions, water-deprivation may confound temperature preferences in brief-access procedures. In contrast, operant conditioning tasks revealed robust temperature effects on sensory-discriminative function. In a two-response taste detection tasks in which mice were trained to distinguish each salt from water, enhanced sensitivity to both NaCl and KCl was observed at 36 °C compared to 14 °C, with detection thresholds significantly lower at warm temperatures. Critically, in discrimination tasks where mice were required to distinguish between NaCl and KCl with stimulus intensity controlled by anchoring concentrations at their respective detection thresholds, mice showed significantly impaired discrimination performance at 36 °C compared to 14 °C, indicating that the qualitative signatures of the two salts became perceptually more similar at the warmer temperatures. These findings demonstrate that temperature profoundly modulates the sensory-discriminative properties of salts: while warm temperatures enhance detection sensitivity, they simultaneously reduce qualitative discriminability between sodium and non-sodium salts. Overall, these results have implications for the operational principles of taste function and highlight the promising possibility that temperature manipulation could serve as an effective strategy for dietary sodium reduction.