ADCYAP1 and Headache: In addition to sensory triggers, a peptide trigger, pituitary adenylate cyclase-activating polypeptide-38 (PACAP38), which was reported to induce migraine-like headaches in migraine patients (Schytz et al., 2009; Ghanizada et al., 2020), decreased right cerebellar functional connectivity with default mode network in the early phase of migraine attacks (Amin et al., 2016).