Ten percent of the brain myth 20th century. For example, the functions of many brain regions (especially in the cerebral cortex) are complex enough that the effects of damage are subtle, leading early neurologists to wonder what these regions did. The brain was also discovered to consist mostly of glial cells, which seemed to have very minor functions. James W. Kalat, author of the textbook "Biological Psychology", points out that neuroscientists in the 1930s knew about the large number of "local" neurons in the brain. The misunderstanding of the function of local neurons may have led to the ten percent myth. The myth might have been
Electrical conduction system of the heart in every direction, so that the myocardium functions as a single contractile unit. This property allows rapid, synchronous depolarization of the myocardium. While advantageous under normal circumstances, this property can be detrimental, as it has potential to allow the propagation of incorrect electrical signals. These gap junctions can close to isolate damaged or dying tissue, as in a myocardial infarction (heart attack). Embryologic evidence of generation of the cardiac conduction system illuminates the respective roles of this specialized set of cells. Innervation of the heart begins with a brain only centered parasympathetic cholinergic first order. It is then followed by