Warm pleasant feelings in the brain

Area of Science:

• Neuroscience
• Affective Science
• Sensory Processing

Background:

• Thermal stimuli (warmth and cold) possess affective qualities (pleasantness/unpleasantness) potentially linked to survival through evolved approach/avoidance behaviors.
• Understanding the neural basis of these prototypical reinforcers offers insight into the brain mechanisms underlying emotion.

Purpose of the Study:

• To investigate the brain processing associated with the affective experience of thermal stimuli using functional magnetic resonance imaging (fMRI).
• To differentiate neural correlates of affective value (pleasantness) from sensory intensity in thermal perception.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was employed in human participants.
• Participants rated the pleasantness of warm (41°C), cold (12°C), and combined thermal stimuli applied to the hand.
• Brain activation patterns were correlated with subjective pleasantness ratings and stimulus intensity.

Main Results:

• Activation in the mid-orbitofrontal cortex, pregenual cingulate cortex, and ventral striatum correlated with subjective pleasantness of thermal stimuli.
• The lateral and anterior orbitofrontal cortex showed activations correlated with stimulus unpleasantness.
• Somatosensory cortex and ventral posterior insula activations correlated with stimulus intensity, but not pleasantness.

Conclusions:

• Neural processing of the affective value and subjective emotional experience of survival-relevant thermal stimuli occurs in distinct brain areas compared to sensory property processing (e.g., intensity).
• This principle, observed with prototypical thermal stimuli, supports a broader model of sensory processing where affective and sensory information are segregated.
• Findings provide strong evidence for distinct neural substrates underlying the emotional and sensory aspects of thermal perception.