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A collection of fragments of understanding in the pursuit of deeper questions.

White & Grey Matter in the Brain

Grey Matter of the Cortex

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Korbinian Brodmann described in 1909 areas of the cerebral cortex on the basis of cytoarchitectural criteria. Areas differ in cell-types, layering and cell distribution, resulting in 52 Brodmann Areas.

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Examples: Brodmann Area 3,1,2 Primary Somatosensory Cortex S1, Brodmann Area 17 Primary Visual Cortex V1.

Cerebral Convolutions: Species Differences

  • Gyrencephalic (Human, Elephant).
  • Lissencephalic (Rabbit, Mouse) (No gyrus structures). Lissencephaly in Humans is due to a defective migration during early to mid-gestation (12^th^ to 24^th^ weeks), leading to impaired development of gyri and sulci.

White Matter: Macroscopic

  • Association Fibers (Green) link cortical areas of the same hemisphere. Arcuate fibers run over short distances, long-distance association fibers have names, such as the Superior and Inferior Longitudinal Bundle/Fasciculus, the Cingulum and Uncinate Bundle.
  • Commissural Fibers (Red) link areas of the two hemispheres (Corpus Callosum, Anterior Commissure, Posterior Commissure).
  • Projecting Fibers (Blue) link the cortex with subcortical areas of the brain and the spinal cord (e.g., Internal Capsule).
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White Matter: Microscopic

  • Oligodendrocytes
  • Microglia
  • Astrocytes