I see one thread about one person whose EEGs showed abnormalities. It seems possible that other types of brain scans might show clear signs of hypersensitivity. Maybe more rapid firing of specific neural pathways. Maybe greater response to certain inputs. If the brain was a network of electronic amplifiers, we could measure inputs and outputs and find what pathways are reacting abnormally. For actual brains, I'm not sure what the capabilities of measurement technology are. It just seems like it might be a reliable abnormality that could be targeted for study, and maybe answer the question of "what in ME is causing this abnormality?" We can't quantitatively measure PEM or fatigue-like symptoms, but hypersensitivity might be a possibility for quantitative measurement.