Is It The Lone Ranger?
The periaqueductal grey (PAG) also known as the ‘central grey’ is the primary control centre for descending pain modulation i.e. suppression of pain. So I get that dimunition of the PAG influence could be involved in migraine. What I don’t get is that this central, supra spinal influence (if) acting alone results in migraine – a unilateral condition. (Remember the Lone Ranger(?)… probably significantly less powerful without Tonto – not to mention Silver!)
My comprehension is stretched to the limit when considering the PAGs (central, supra spinal influence) relevance to an alternating, unilateral condition. Why does the PAG choose one side only (i.e. side-locked headache or one side and then the other on the next occasion (i.e. alternating)?