According to the biobehavioral model for migraine, intrisic (brain) noradrenergic system was considered the prime source of origin of migraine attacks (Prof. Welch).

This put the autonomic nervous system's role in migraine in a jeopardy, as we all scientists began believing the same and labelling the "sleeping" but most effective "protective" system of our bodies directly in the pathway of the pathogenesis of migraine attacks. Prof. Welch himself declared in his seminal article that such pathogenetic involvement of the intrinsic brain noradrenergic system was speculative. But the damage to conceptual thinking was done, and, carried forward the serendipity of migraine pathophysiology that had started much earlier in 1967.  

This was the era of the beginning of the impact of high-technology in Neuroscience to hit migraine research and researchers. The twin whammy of added speculation regarding migraine mechanisms and the get-lost factor of high technology proved detrimental to progress in migraine research. The vogue of thinking-through-technology has settled in the deepest and farthest nooks-and-crannies of our minds. 

From a humble, cautious, almost disdain-laden start, mathematics invaded medical research via the portal of statistics, and, grew up into an independent specialization by itself around the same era. From around 1980, the p-value has a life to itself, and, if you (or the reviewer or the editorial team) can still understand the esoteric subject, perhaps the statistician hasn't done her/his job well. Standing tall against logic, common sense, clinical jugdment, and sense and sensibility, statistics towers in Medicine, in clinical trials, in meta-analysis and has left the science of the biology of medicine floundering as never before. More, in the next question.