Functionally, these neurons are either motor (conducting impulses that will cause activity such as the contraction of muscles) or association (conducting impulses and permitting 'communication' between neurons within the central nervous system).
The scant research that has been done on the causes of pica suggests that the disorder is a specific appetite caused by mineral deficiency in many cases, such as iron deficiency, which sometimes is a result of celiac disease or hookworm infection.
I Have Pica Syndrome. Xylophagia. I admit it; I have Pica Syndrome. I didn't even know I had this eating disorder before, I just always had a craving, an urge to eat toilet paper or any paper of that matter. I finally realized it when I was watching 1000 Ways To Die on Spike TV and there was this guy with Pica Syndrome who swallowed pennies, pins, any metal object.