Discrepancy between perceived pain and cortical processing: A voxel-based morphometry and contact heat evoked...

Area of Science:

• Neuroscience
• Neuroimaging
• Pain Perception

Background:

• Individual variability exists in pain perception and evoked potential responses.
• Understanding the neuroanatomical basis of this variability is crucial for accurate pain assessment.

Purpose of the Study:

• To investigate if local gray and white matter volume differences correlate with variability in contact heat evoked potential (CHEP) stimulation responses.
• To determine the role of neuroanatomy in the discrepancy between subjective pain ratings and objective physiological measures.

Main Methods:

• Utilized structural magnetic resonance imaging (MRI) and voxel-based morphometry (VBM) on 30 healthy subjects.
• Administered contact heat stimulation to the hand and recorded evoked potentials.
• Analyzed correlations between brain morphometry, CHEP amplitude, and pain ratings.

Main Results:

• No significant correlation was found between CHEP amplitude, pain rating, and overall brain morphometry after controlling for covariates.
• A significant interaction between pain rating and N2 amplitude was identified in the right insular cortex gray matter (p<0.05, FWE).
• A significant interaction was also found in the white matter, specifically the right inferior frontal occipital fasciculus (p<0.05, FWE).

Conclusions:

• Gray matter volume in the right insular cortex significantly mediates the relationship between CHEP amplitude and pain perception.
• Observed discrepancies between pain ratings and evoked potential amplitudes are partly due to individual anatomical variations, not solely measurement artifacts.