ID 379 – Individual operculo-insular responses to painful heat and non-painful heat stimulations with 3Tesla-fMRI

Objective To assess individual brain responses to either painful heat or non-painful heat stimuli in the operculo-insular cortices. To determine whether painful heat stimulations activate specific parts of the insula or whether insula was activated unspecifically by painful and non-painful heat stimulations. Methods Heat stimulations were applied on the back of 20 subjects’ left hand. Twenty-four stimulations (7 s duration) were applied for each session, interleaved with rest periods which duration was randomized. Regions of interest (ROIs) of the MNI template were transformed to match patients’ brain. Within each ROI, intensity of activations and number of activated voxels were statistically compared for painful and non-painful stimulations. Results For painful heat stimulations, contralateral and ipsilateral insulae were activated almost consistently across subjects, especially in the anterior part. For non-painful heat stimulations, both intensity of activation and number of activated voxels are less consistent, located in the same subdivisions but mainly contralateral to stimulation. Conclusions Painful heat stimulations involve quite specifically the ipsilateral insula. Anterior insula is the most consistently activated area with a higher intensity of activation for painful heat as compared to non-painful heat stimulations. Key message Individual fRMI responses to heat pain prevail in anterior insulae and associate bilateral responses.