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Grey matter, or brain matter in American English, is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and unmyelinated axons), glial cells (astrocytes and oligodendrocytes), synapses, and capillaries.
The neurons of the cerebral cortex reside in a thin layer of gray matter, only 2–4 mm thick, at the surface of the brain. [2] Much of the interior volume is occupied by white matter, which consists of long axonal projections to and from the cortical neurons residing near the
The periaqueductal gray (PAG), also known as the central gray, is a brain region that plays a critical role in autonomic function, motivated behavior and behavioural responses to threatening stimuli. [1] [2] PAG is also the primary control center for descending pain modulation. It has enkephalin-producing cells that suppress pain.
The cortical layers of neurons constitute much of the cerebral grey matter, while the deeper subcortical regions of myelinated axons, make up the white matter. [7] The white matter of the brain makes up about half of the total brain volume. [16]
The thalamus is a paired structure of gray matter about four centimetres long, located in the forebrain which is superior to the midbrain, near the center of the brain with nerve fibers projecting out to the cerebral cortex in all directions.
In humans, the cerebrum is the largest and best-developed of the five major divisions of the brain. The cerebrum is made up of the two cerebral hemispheres and their cerebral cortices (the outer layers of grey matter), and the underlying regions of white matter. [2] Its subcortical structures include the hippocampus, basal ganglia and olfactory ...
When examining blood oxygen levels, scientists found that lower oxygen levels during sleep was correlated with both higher hippocampal volume and white matter hyperintensities, or areas of brain ...
The substantia nigra is a third colored component found in the brain that appears darker due to higher levels of melanin in dopaminergic neurons than its nearby areas. Note that white matter can sometimes appear darker than grey matter on a microscope slide because of the type of stain used.