Grey matter (or gray matter) (lat. Substantia grisea) is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and myelinated as well as unmyelinated axons), glial cells (astroglia and oligodendrocytes) and capillaries. Grey matter is distinguished from white matter, in that grey matter contains numerous cell bodies and relatively few myelinated axons, while white matter is composed chiefly of long-range myelinated axon tracts and contains relatively very few cell bodies. The color difference arises mainly from the whiteness of myelin. In living tissue, grey matter actually has a very light grey color with yellowish or pinkish hues, which come from capillary blood vessels and neuronal cell bodies.
Grey matter contains most of the brain's neuronal cell bodies. The grey matter includes regions of the brain involved in muscle control,and sensory perception such as seeing and hearing, memory, emotions, speech, decision making, and self-control. While 20% of all oxygen taken in by the body goes to the brain, 95% of that goes specifically into the grey matter.
Grey matter is distributed at the surface of the cerebral hemispheres (cerebral cortex) and of the cerebellum (cerebellar cortex), as well as in the depths of the cerebrum (thalamus; hypothalamus; subthalamus, basal ganglia - putamen, globus pallidus, nucleus accumbens; septal nuclei), cerebellar (deep cerebellar nuclei - dentate nucleus, globose nucleus, emboliform nucleus, fastigial nucleus), brainstem (substantia nigra, red nucleus, olivary nuclei, cranial nerve nuclei) and spinal grey matter (anterior horn, lateral horn, posterior horn). Grey matter undergoes development and growth throughout childhood and adolescence.
Volume and cognition in elderly people
Significant positive correlations have been found between grey matter volume in elderly persons and measures of semantic and short-term memory. No significant correlations with white matter volume were found. These results suggest that individual variability in specific cognitive functions that are relatively well preserved with ageing is accounted for by the variability of gray matter volume in healthy elderly subjects.
Volume associated with bipolar disorder
Some structural differences in grey matter may be associated with psychiatric disorders. There was no difference in whole-brain grey matter volume between patients with bipolar I disorder and healthy controls. Subjects with bipolar I disorder had smaller volumes in the left inferior parietal lobule, right superior temporal gyrus, right middle frontal gyrus, and left caudate. Only the volume of the right middle frontal gyrus was correlated with duration of illness and the number of episodes in patients.
Effects of smoking
Older smokers lose grey matter and cognitive function at a greater rate than non-smokers. Chronic smokers who quit during the study lost fewer brain cells and retained better intellectual function than those who continued to smoke.
Effects of child abuse
Adolescents who were subjected to abuse and neglect appear to have decreased grey matter in the prefrontal cortex.
In the current edition of the official Latin nomenclature, Terminologia Anatomica, substantia grisea is used for English grey matter. The adjective grisea for grey is however not attested in classical Latin. The adjective grisea is derived from the French word for grey, gris. Alternative designations like substantia cana and substantia cinerea are being used alternatively. The adjective cana, attested in classical Latin, can mean grey, or greyish white. The classical Latin cinerea means ash-colored.
Human brain right dissected lateral view
Schematic representation of the chief ganglionic categories (I to V).
- Grey matter heterotopia
- Rexed laminae
- Substantia nigra
- White matter
- Grey column
- at eMedicine Dictionary