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Fractional anisotropy – a measure often used in diffusion imaging where it is thought to reflect fiber density, axonal diameter, and myelination in white matter. The FA is an extension of the concept of eccentricity of conic sections in three dimensions, normalized to the unit range.
White matter is named for its relatively light appearance resulting from the lipid content of myelin. However, the tissue of the freshly cut brain appears pinkish-white to the naked eye because myelin is composed largely of lipid tissue veined with capillaries. Its white color in prepared specimens is due to its usual preservation in formaldehyde.
The following diagram is provided as an overview of and topical guide to the human nervous system: Human nervous system. Human nervous system – the part of the human body that coordinates a person's voluntary and involuntary actions and transmits signals between different parts of the body.
Being rich in lipid, myelin appears white, hence the name given to the "white matter" of the CNS. Both CNS white matter tracts (e.g. the optic nerve, corticospinal tract and corpus callosum) and PNS nerves (e.g. the sciatic nerve and the auditory nerve, which also appear white) each comprise thousands to millions of axons, largely aligned in ...
The atlas is based on magnetic resonance imaging (MRI). It traces the growth, white matter, connectivity, and development of the C57BL/6 mouse brain from embryonic day 12 to postnatal day 80. [5] This atlas enhances the ability of neuroscientists to study how pollutants and genetic mutations effect the development of
Diffusion tensor imaging is being developed for studying the diseases of the white matter of the brain as well as for studies of other body tissues (see below). DWI is most applicable when the tissue of interest is dominated by isotropic water movement e.g. grey matter in the cerebral cortex and major brain nuclei, or in the body—where the ...
Myelin is formed by oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system.Therefore, the first stage of myelinogenesis is often defined as the differentiation of oligodendrocyte progenitor cells (OPCs) or Schwann cell progenitors into their mature counterparts, [4] followed by myelin formation around axons.
A functional brain atlas is made up of regions of interest, where these regions are typically defined as spatially contiguous and functionally coherent patches of gray matter. [2] In most atlases, the three dimensions are: latero-lateral (x), dorso-ventral (y) and rostro-caudal (z). The possible sections are coronal; sagittal; transverse