Poster # 29

Category: Pre-Doctoral/Post-Doctoral Bio-Medical/Basic Science


RL Quiton1,2, SR Royas3, J Zhuo3, ML Keaser2, RP Gallapalli3, JD Greenspan1,2

1Program in Neuroscience, University of Maryland, Baltimore (UMB); 2Dept. Biomedical Sciences, UMB Dental School; 3Dept. Diagnostic Radiology, UMB School of Medicine

Increased prevalence of persistent pain with advancing age may be due to age-related changes in the nociceptive system.  This study used functional MRI (fMRI) to compare cortical responses to painful heat in healthy young (ages 22-30, n=7) and older (ages 56-57, n=7) subjects.  Subjects participated in 6 fMRI scans (3 sessions, 2 scans/session) in which painful heat stimuli were delivered to the left dorsal forearm.  Using a regression model, significant pain-related activation was identified in cortical regions of interest (ROI) involved in nociceptive processing: 1st and 2nd somatosensory cortices (S1 & S2), anterior cingulate, anterior and posterior insula (aINS & pINS), supplementary motor area (SMA), and inferior frontal gyrus.  For each ROI, two measures of pain-related activation were calculated: number of significantly active voxels (spatial extent) and signal amplitude (amplitude).  Older subjects had a significantly lower signal amplitude in contralateral and ipsilateral aINS (mixed-effects model, p=0.001 and 0.04, respectively) and smaller spatial extent in contralateral S1 (p=0.03), ipsilateral aINS (p=0.03), and ipsilateral SMA (p=0.02).  Gray matter volumes in S1 and aINS were smaller for the older group (t-test, p=0.02 and 0.001, respectively), with no significant differences in any other ROI.  In conclusion, painful heat stimuli produce smaller fMRI signal changes and activation extent for older subjects in the aINS, an area associated with processing emotional aspects of pain and interoception.  Reduced gray matter volume in the aINS and S1 in older subjects may underlie the smaller fMRI responses observed in these regions.  (Supported by NIH R03 AG22223-01/R01 NS39337).