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The gray matter changes can be observed via both gray matter density and gyrification. That the white matter loss is not nearly as clear as that for gray matter indicates that changes also occur in non-neural tissue, e.g. the vasculature or microglia.
White matter is composed of bundles, which connect various grey matter areas (the locations of nerve cell bodies) of the brain to each other, and carry nerve impulses between neurons. Myelin acts as an insulator, which allows electrical signals to jump , rather than coursing through the axon, increasing the speed of transmission of all nerve ...
Grey matter is distinguished from white matter in that it contains numerous cell bodies and relatively few myelinated axons, while white matter contains relatively few cell bodies and is composed chiefly of long-range myelinated axons. [1] The colour difference arises mainly from the whiteness of myelin. In living tissue, grey matter actually ...
However, detailed analyses of white matter microstructure revealed that superagers had higher fractional anisotropy and lower mean diffusivity — two measures related to brain decline at a ...
The VBM analysis showed global gray matter was decreased linearly with age, especially for men, whereas global white matter did not decline with age. A key description of the methodology of voxel-based morphometry is Voxel-Based Morphometry—The Methods [9] —one of the most cited articles in the journal NeuroImage. [10]
On images of the brain, this sequence has a more pronounced distinction between grey matter (bright) and white matter (darker grey), but with little contrast between brain and CSF. [36] It is very useful for the detection of arthropathy and injury.
Diffusion tensor imaging (DTI) is important when a tissue—such as the neural axons of white matter in the brain or muscle fibers in the heart—has an internal fibrous structure analogous to the anisotropy of some crystals. Water will then diffuse more rapidly in the direction aligned with the internal structure (axial diffusion), and more ...
Histologically, grey matter is more vulnerable than white matter to necrosis due to lack of oxygen. The third layer of the grey matter is the most vulnerable. Damage is greater in the sulci when compared to gyri of the brain. [2] When seen on CT scan, it shows hyperdensity in the surface of the cortex.