Fig. 3.

Significant differences in signal intensity changes during 8 noxious thermal stimuli in migraineurs immediately prior to a migraine headache compared with controls. Significant clusters are overlaid onto a mean T1-weighted anatomical image. Slice locations in Montreal Neurological Institute space are indicated to the top right of each slice. Note that signal increase changes were significantly greater in four main regions; the ipsilateral nucleus accumbens, contralateral ventrolateral prefrontal cortex (vlPFC) and two clusters in the dorsolateral prefrontal cortex (dlPFC). Plots of mean (±SEM) beta values (effect sizes) for each of these four clusters revealed that acute orofacial pain evoked significant signal intensity increases in migraineurs only during the 24-h period immediately prior to migraine, that is signal changes were not different between controls and migraineurs during the interictal phase