Figure 5.

Midbrain ascending arousal network nuclei under stress. Prolonged or severe stressors can cause degeneration into maladaptation that tips the balance toward a dysfunctional state. Changes compared to Figure 4 emphasize potential alterations in ME/CFS and GWI. Stressors may have exaggerated consequences in particularly vulnerable populations. For example, VTA may balance between reward and motivation vs. anhedonia. DR and MR are poised between tolerance of aversive conditions and anxiety, affective and limbic system dysfunction. Glutamine and GABA balance the tolerance of pain vs. the development of systemic hyperalgesia. Arousal network nuclei with significant incremental changes in BOLD signal between days (∆) were outlined in red.