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White matter is the tissue through which messages pass between different areas of grey matter within the central nervous system. The white matter is white because of the fatty substance (myelin) that surrounds the nerve fibers (axons). This myelin is found in almost all long nerve fibers, and acts as an electrical insulation.
Grey matter contains most of the brain's neuronal cell bodies. [6] The grey matter includes regions of the brain involved in muscle control, and sensory perception such as seeing and hearing, memory, emotions, speech, decision-making, and self-control. The grey matter in the spinal cord is split into three grey columns:
Tangential growth suggests that the grey matter grows at a faster rate than the inner white matter and that the growth rate of the grey matter determines the growth rate of the white matter. Though both methods are differential, with the cortex growing more rapidly than the subcortex, tangential growth has been suggested as a more plausible model.
Similar to grey matter, white matter has been shown to correlate positively with intelligence in humans. [1] [4] White matter consists mainly of myelinated neuronal axons, responsible for delivering signals between neurons. The pinkish-white color of white matter is actually a result of these myelin sheaths that electrically insulate neurons ...
Researchers analyzing the white matter of superagers over a 5-year period found that despite comparable overall white matter health with typical older adults, superagers exhibited superior ...
The brain can thus be described as being divided into left and right cerebral hemispheres. Each of these hemispheres has an outer layer of grey matter, the cerebral cortex, that is supported by an inner layer of white matter. In eutherian (placental) mammals, the hemispheres are linked by the corpus callosum, a very large bundle of nerve fibers.
The cortical layers of neurons constitute much of the cerebral grey matter, while the deeper subcortical regions of myelinated axons, make up the white matter. [7] The white matter of the brain makes up about half of the total brain volume. [16]
The cerebral blood volume value of gray matter is about 3.5 +/- 0.4 ml/100g, and the white matter is about 1.7 +/- 0.4 ml/100g. The gray matter is nearly twice that of white matter. [3] In both white and gray matter, cerebral blood volume decreases by about 0.50% per year with increasing age. [4]