Search results
Results from the WOW.Com Content Network
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.
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.
Myelination is only prevalent in a few brain regions at birth and continues into adulthood. The entire process is not complete until about 25–30 years of age. [24] Myelination is an important component of intelligence, and white matter quantity may be positively correlated with IQ test results in children. [24]
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 ...
A structure that Sachs labeled the stratum profundum convexitatis in his atlas was the subject of controversy at the time, with leading neuropathologist Theodor Meynert denying its very existence; it is now known as the vertical occipital fasciculus. [3] [4] Sachs also published on aphasia (1893, 1905) and traumatic neurosis (1909). [2]
The medial lemniscus carries axons from most of the body and terminates by synapsing with third-order neurons in the ventral posterolateral nucleus of the thalamus. [3] at the level of the mamillary bodies. Sensory axons transmitting information from the head and neck via the trigeminal nerve synapse at the ventral posteromedial nucleus of the ...
The uncinate fasciculus is a white matter association tract in the human brain that connects parts of the limbic system such as the temporal pole, anterior parahippocampus, and amygdala in the temporal lobe with inferior portions of the frontal lobe such as the orbitofrontal cortex.
White matter, which is mostly composed of myelinated axons (hence its white color) and glial cells, is generally not considered to be a part of the neuropil. [citation needed] Neuropil (pl. neuropils) comes from the Greek: neuro, meaning "tendon, sinew; nerve" and pilos, meaning "felt". [2] The term's origin can be traced back to the late 19th ...