Human cortical representation of oral temperature

Area of Science:

• Neuroscience
• Sensory Science
• Food Science

Background:

• Oral temperature influences food and fluid pleasantness and acceptability.
• Nonhuman primate studies indicate cortical taste neurons process both chemosensory and oral temperature inputs.
• The human insular cortex, particularly middle and posterior regions, is implicated in processing thermal information.

Purpose of the Study:

• To investigate if oral temperature changes activate human taste-related brain areas.
• To identify brain regions responding to intra-oral thermal stimulation.
• To correlate brain activation patterns with subjective pleasantness ratings of oral temperature.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to monitor brain activity.
• Participants received innocuous, temperature-controlled liquid stimuli (5, 20, 50°C) in their mouths.
• Taste stimuli (glucose) were used to identify the insular taste cortex for comparison.

Main Results:

• Intra-oral thermal stimuli activated several brain regions, including the insular taste cortex, somatosensory cortex, orbitofrontal cortex, anterior cingulate cortex, and ventral striatum.
• Brain activations in the orbitofrontal cortex and pregenual cingulate cortex correlated with the pleasantness ratings of oral temperature stimuli.
• A network of taste- and reward-responsive brain regions is activated by oral thermal stimulation.

Conclusions:

• The human brain network involved in taste and reward processing also responds to intra-oral thermal stimulation.
• Pleasant subjective experiences of oral temperature are associated with activity in the orbitofrontal and pregenual cingulate cortices.
• Shared neural representation of oral temperature and taste/flavor pleasantness in the brain may influence overall food palatability.