Salt taste inhibition by cathodal current

Area of Science:

• Neuroscience
• Sensory Science
• Electrophysiology

Background:

• Taste perception is influenced by the ionic composition of stimuli.
• Electrically charged ions play a critical role in taste receptor activation.
• Understanding ion-specific effects is crucial for elucidating taste mechanisms.

Purpose of the Study:

• To investigate the role of cations and anions in human salt taste perception using cathodal current.
• To determine how cathodal current affects various taste qualities, including salty, bitter, sour, and sweet.
• To explore the underlying mechanisms of cathodal current's influence on taste receptors.

Main Methods:

• Applying cathodal currents (-40 microA to -80 microA) to human tongues using supra-threshold salt solutions.
• Testing a range of salts including sodium chloride, potassium chloride, calcium chloride, and various sodium salts with different anions.
• Recording analogous effects from the hamster chorda tympani nerve to corroborate human findings.

Main Results:

• Cathodal current inhibited the taste of sodium chloride, chloride salts, and sodium nitrate, suggesting cation displacement from receptors.
• Bitter tastes of non-halide sodium salts were not inhibited, indicating anion involvement in some bitter taste pathways.
• A metallic taste was evoked upon current cessation, similar to anodal electrogustometry findings.
• Cathodal current did not enhance tastes associated with saccharin or benzoate anions, suggesting limited anion transport to sweet receptors.

Conclusions:

• Cathodal current selectively inhibits salty and bitter-salty tastes mediated by cation stimuli.
• Taste receptor responses to anions may differ from those to cations, particularly for bitter and sweet tastes.
• Electrically-induced ion movement provides insights into the specific roles of cations and anions in taste perception.