ABSTRACT
Objective To investigate the functional activity and connectivity of the insular cortex at rest in persons with low back pain (LBP).Methods Twelve healthy subjects (male 6,female 6 ; age 24.8 ± 3.3 years) were given fMRI 3.0T scans at rest.Back muscle pain was then induced with an intramuscular injection of 3％ hypertonic saline solution and a second scan was performed.The pain-free and in-pain fMRI data were compared using paired t-tests to highlight any changes in the functional connectivity of the anterior and posterior insular cortex on both sides.Pain severity was quantified using a visual analogue scale (VAS).Results Ratings of LBP severity peaked at 6.02 ± 1.96 on the VAS.The functional connectivity of the inferior insular cortex with the frontal cortex,the thalamus and the parahippocampal gyrus was enhanced when the subjects were in pain,but connectivity with the posterior cingulate cortex,the precuneus,the temporal cortex,the paracentral lobule and the cerebellar tonsil was reduced.The inferior parietal lobule exhibited significantly enhanced connectivity with the anterior insular cortex,but reduced connectivity with the posterior insular cortex.In addition,the medial cingulate cortex displayed decreased functional connectivity with the anterior insular cortex,but increased functional connectivity with the posterior insular cortex when the subjects were in pain.Conclusion This study has revealed impeded functional connectivity of the insular cortex when experiencing LBP at rest.This may possibly be related to pain's disruption of cognition and emotion.