I am a plasma physicist so I apologize in advance for my biology ignorance.
I recall from a neuropsychology class I took in college (used Lezak, Howieson, and Loring, 4th Edition) that there are several types of glial cells, at least one of which acts to prune neurons in your brain. I am curious if those with an eidetic memory have fewer or different or altered glial cells? That is, could the pruning done by some glial cells affect long-term memory or brain function but not be operating (or at least in a diminished capacity) in those with an eidetic memory?
I found a somewhat related question but it's not directly tied to this one: Is an Eidetic Memory (or other unusual forms of memory) less susceptible to anterograde amnesia?
Lezak, M.D., D.B. Howieson, and D.W. Loring Neuropsychological Assessment, 4th Edition, Oxford University Press, Inc., New York, New York, 2004.