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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 ...
These perisomatic (around the cell body) and basal dendrites project into all cortical layers, but most of their horizontal branches/arbors populate layers V and VI, some reaching down into the white matter. [5] According to one study, Betz cells represent about 10% of the total pyramidal cell population in layer Vb of the human primary motor ...
Pathways through cerebral white matter can be charted by histological dissection and staining, by degeneration methods, and by axonal tracing. Axonal tracing methods form the primary basis for the systematic charting of long-distance pathways into extensive, species -specific anatomical connection matrices between gray matter regions.
The white matter is located outside of the gray matter and consists almost totally of myelinated motor and sensory axons. “Columns” of white matter carry information either up or down the spinal cord. Within the CNS, nerve cell bodies are generally organized into functional clusters, called nuclei. Axons within the CNS are grouped into tracts.
A deficiency in GALC thus causes a buildup of these fatty acids, leading to an incursion by cells called "globoid macrophages" that destroy oligodendrocytes, thereby inhibiting any further myelin formation. [20] Given the presence of globoid macrophages clustered near white matter, Krabbe disease often is called globoid cell leukodystrophy.
In neuroanatomy, the medullary pyramids are paired white matter structures of the brainstem's medulla oblongata that contain motor fibers of the corticospinal and corticobulbar tracts – known together as the pyramidal tracts. The lower limit of the pyramids is marked when the fibers cross .
OPCs comprise approximately 3–4% of cells in grey matter and 8–9% in white matter, making them the fourth largest group of glia after astrocytes, microglia and oligodendrocytes. [ 6 ] OPCs are present throughout the brain, including the hippocampus and in all layers of the neocortex . [ 7 ]
There are four paired deep cerebellar nuclei embedded in the white matter centre of the cerebellum.The nuclei are the fastigial, globose, emboliform, and dentate nuclei.. In lower mammals the emboliform nucleus appears to be continuous with the globose nucleus, and these are known together as the interposed nucleus.