Dendritic Spine Morphology: The Role of Micro tubules and Endosomes

Abstract

In Ancient Egypt, the function of the brain was regarded as not much more than cranial stuffing. The brain was regularly removed in preparation for mummification since the heart was assumed to be the organ of intelligence. Over the next five thousand years, this view was reversed; the brain is now known to be the control center of the central nervous system that is responsible for regulating virtually all activities of the body and is the source of perception and higher cognitive functions in humans. The simplest possible multicellular organisms have very simple nervous systems made up of a few neurons that mediate a reflex action. Smaller invertebrates, such as the flatworm, do not have a centralized brain but loose associations of neurons arranged in simple reflex pathways along the body. Larger invertebrates, such as the lobster have simple "brains" that consist oflocalizcd collections of neuronal cell bodies called ganglia. Each ganglion controls sensory and motor functions in its segment through reflex pathways, and the ganglia arc linked together to form a simple nervous system. In higher organisms the nervous systems evolve from the chains of ganglia cells into more centralized brain structures. In mammals the brain is extremely complex and is divided in different functional regions, such as for example the brain stem, cerebellum, and cerebral cortex.