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.
1 Nondiscriminating oral behavior: In individuals with mental retardation, pica has been suggested to result from an inability to discriminate between food and nonfood items; however, this theory is not supported by findings of selection of pica items and the often aggressive search for nonfood items of choice.