Altered resting-state ascending/descending pathways associated with the posterior thalamus in migraine without aura

This study aimed to investigate the dysfunctional ascending/descending pain pathways at the thalamic level in patients with migraine without aura (MWoA) using the effective connectivity analysis of the resting-state functional MRI. Twenty MWoA and 25 matched healthy controls participated in the resting-state functional MRI scans. The directional interactions between the posterior thalamus (PTH) and other brain regions were investigated using the Granger causality analysis and choosing bilateral PTH as two individual seeds. Pearson's correlation analysis was carried out between the abnormal effective connectivity and the headache duration and pain intensity of MWoA. Compared with healthy controls, MWoA showed decreased inflows to the bilateral PTH from the ventromedial prefrontal cortex and the left precuneus/posterior cingulate cortex, decreased outflow from the left PTH to the ipsilateral dorsomedial prefrontal cortex, and increased inflow to the right PTH from the ipsilateral dorsolateral prefrontal cortex. In addition, the abnormal inflows to the right PTH from the ventromedial prefrontal cortex and the right dorsolateral prefrontal cortex correlated positively with the headache duration and pain intensity, respectively. The abnormal ascending/descending pain pathways between the thalamus and these cortical regions indicate a disrupted pain modulation in affective and sensory domains, which suggests a disequilibrium of pain inhibition and facilitation in MWoA. These findings may help to shed light on the pathophysiologic mechanisms of migraine.