| Factors | Regions |
| Chronic pain | Cingulate cortex, prefrontal cortex, insula, and dorsal pons [55] |
| Personality | Orbitofrontal, occipital, and parietal structures; anterior prefrontal cortex (negatively related to women) [63] |
| Stress | Right orbitofrontal area of the prefrontal cortex [66ā68] |
| Psychiatric disorder | Amygdala, hippocampal and parahippocampal, the ventral, medial temporal lobes, insular cortex [80] |
| Physical activity | Right prefrontal and cingulate cortex, left prefrontal cortex, cingulate cortex, bilateral occipitotemporal regions, and cerebellum, right anterior frontal cortex, middle prefrontal gyrus, anterior cingulate cortex, and supplementary motor area [83, 84] |
| Insomnia | Left orbitofrontal cortex, bilateral anterior precuneus of the parietal cortex, and bilateral posterior precuneus in the occipitoparietal cortex [85] |
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