Grey matter is a major component of the central nervous system

Central nervous system

The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...

, consisting of neuron

Neuron

A neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...

al cell bodies

Soma (biology)

The soma , or perikaryon , or cyton, is the bulbous end of a neuron, containing the cell nucleus. The word "soma" comes from the Greek σῶμα, meaning "body"; the soma of a neuron is often called the "cell body"...

, neuropil

Neuropil

In neuroanatomy, a neuropil, which is sometimes referred to as a neuropile, is a region between neuronal cell bodies in the gray matter of the brain and blood-brain barrier . It consists of a dense tangle of axon terminals, dendrites and glial cell processes...

 (dendrites and unmyelinated

Myelin

Myelin is a dielectric material that forms a layer, the myelin sheath, usually around only the axon of a neuron. It is essential for the proper functioning of the nervous system. Myelin is an outgrowth of a type of glial cell. The production of the myelin sheath is called myelination...

 axons), glial cell

Glial cell

Glial cells, sometimes called neuroglia or simply glia , are non-neuronal cells that maintain homeostasis, form myelin, and provide support and protection for neurons in the brain, and for neurons in other parts of the nervous system such as in the autonomous nervous system...

s (astroglia and oligodendrocytes) and capillaries

Capillary

Capillaries are the smallest of a body's blood vessels and are parts of the microcirculation. They are only 1 cell thick. These microvessels, measuring 5-10 μm in diameter, connect arterioles and venules, and enable the exchange of water, oxygen, carbon dioxide, and many other nutrient and waste...

. Grey matter contains neural cell bodies, in contrast to white matter

White matter

White matter is one of the two components of the central nervous system and consists mostly of myelinated axons. White matter tissue of the freshly cut brain appears pinkish white to the naked eye because myelin is composed largely of lipid tissue veined with capillaries. Its white color is due to...

, which does not and mostly contains myelinated axon tracts. The color difference arises mainly from the whiteness of myelin. In living tissue, grey matter actually has a grey-brown color, which comes from capillary blood vessels and neuronal cell bodies.

Function

Grey matter is made up of neuronal cell bodies. The grey matter includes regions of the brain involved in muscle control, sensory perception such as seeing and hearing, memory, emotions, and speech.

Distribution

Grey matter is distributed at the surface of the cerebral hemisphere

Cerebral hemisphere

A cerebral hemisphere is one of the two regions of the eutherian brain that are delineated by the median plane, . The brain can thus be described as being divided into left and right cerebral hemispheres. Each of these hemispheres has an outer layer of grey matter called the cerebral cortex that is...

s (cerebral cortex

Cerebral cortex

The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different...

) and of the cerebellum

Cerebellum

The cerebellum is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses, but its movement-related functions are the most solidly established...

 (cerebellar cortex), as well as in the depths of the cerebrum (thalamus

Thalamus

The thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections...

; hypothalamus

Hypothalamus

The Hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions...

; subthalamus

Subthalamus

The subthalamus is a part of the diencephalon. Its major part is the subthalamic nucleus. Functionally, it also encompasses the globus pallidus, which is topographically part of the telencephalon.-Anatomy:...

, basal ganglia

Basal ganglia

The basal ganglia are a group of nuclei of varied origin in the brains of vertebrates that act as a cohesive functional unit. They are situated at the base of the forebrain and are strongly connected with the cerebral cortex, thalamus and other brain areas...

 - putamen

Putamen

The putamen is a round structure located at the base of the forebrain . The putamen and caudate nucleus together form the dorsal striatum. It is also one of the structures that comprises the basal ganglia. Through various pathways, the putamen is connected to the substantia nigra and globus pallidus...

, globus pallidus

Globus pallidus

The globus pallidus also known as paleostriatum, is a sub-cortical structure of the brain. Topographically, it is part of the telencephalon, but retains close functional ties with the subthalamus - both of which are part of the extrapyramidal motor system...

, nucleus accumbens

Nucleus accumbens

The nucleus accumbens , also known as the accumbens nucleus or as the nucleus accumbens septi , is a collection of neurons and forms the main part of the ventral striatum...

; septal nuclei

Septal nuclei

The septal area are structures that lie below the rostrum of corpus callosum in front of lamina terminalis , composed of medium-size neurons grouped into medial, lateral, and posterior groups...

), cerebellar (deep cerebellar nuclei - dentate nucleus

Dentate nucleus

The dentate nucleus is located within the deep white matter of each cerebellar hemisphere, and it is the largest single structure linking the cerebellum to the rest of the brain. It is the largest and most lateral, or farthest from the midline, of the four pairs of deep cerebellar nuclei, the...

, globose nucleus

Globose nucleus

The globose nucleus is one of the deep cerebellar nuclei. It is located medial to the emboliform nucleus and lateral to the fastigial nucleus. This nucleus contains primarily large and small multipolar neurons....

, emboliform nucleus

Emboliform nucleus

The emboliform nucleus lies immediately to the medial side of the nucleus dentatus, and partly covering its hilus. It is one among the four pairs of cerebellar nuclei, which are from lateral to medial: the dentate, interposed , and fastigial nuclei...

, fastigial nucleus

Fastigial nucleus

The fastigial nucleus or nucleus fastigii refers specifically to the concentration of gray matter nearest to the middle line at the anterior end of the superior vermis, and immediately over the roof of the fourth ventricle, from which it is separated by a thin layer of white matter...

), brainstem (substantia nigra

Substantia nigra

The substantia nigra is a brain structure located in the mesencephalon that plays an important role in reward, addiction, and movement. Substantia nigra is Latin for "black substance", as parts of the substantia nigra appear darker than neighboring areas due to high levels of melanin in...

, red nucleus

Red nucleus

The red nucleus is a structure in the rostral midbrain involved in motor coordination. It comprises a caudal magnocellular and a rostral parvocellular part.-Function:...

, olivary nuclei

Olivary body

In anatomy, the olivary bodies or simply olives are a pair of prominent oval structures in the medulla oblongata, the lower portion of the brainstem...

, cranial nerve nuclei) and spinal

Spinal cord

The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system...

 grey matter (anterior horn

Anterior horn (spinal cord)

The anterior horn of the spinal cord is the ventral grey matter section of the spinal cord. The anterior horn contains motor neurons that affect the axial muscles while the posterior horn receives information regarding touch and sensation...

, lateral horn

Lateral horn

In the thoracic region, the postero-lateral part of the anterior column projects lateralward as a triangular field, which is named the lateral column .-Nerve Cells in the Lateral Column:...

, posterior horn

Posterior horn of lateral ventricle

The posterior horn of the lateral ventricle passes into the occipital lobe, its direction being backward and lateralward, and then medialward....

).

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

Bipolar I disorder

Bipolar I disorder is a mood disorder that is characterized by at least one manic or mixed episode. There may be episodes of hypomania or major depression as well...

 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.

See also

• Gray matter heterotopia
  Gray Matter Heterotopia
  Gray matter heterotopia is a neurological disorder caused by clumps of grey matter being located in the wrong part of the brain. It is characterized as a type of cortical dysplasia. The neurons in heterotopia appear to be normal, except for their mislocation; nuclear studies have shown glucose...
  
  
• Neuropil
  Neuropil
  In neuroanatomy, a neuropil, which is sometimes referred to as a neuropile, is a region between neuronal cell bodies in the gray matter of the brain and blood-brain barrier . It consists of a dense tangle of axon terminals, dendrites and glial cell processes...
  
  
• Rexed laminae
  Rexed laminae
  The Rexed laminae comprise a system of ten layers of grey matter , identified in the early 1950s by Bror Rexed to label portions of the spinal cord...
  
  
• Substantia nigra
  Substantia nigra
  The substantia nigra is a brain structure located in the mesencephalon that plays an important role in reward, addiction, and movement. Substantia nigra is Latin for "black substance", as parts of the substantia nigra appear darker than neighboring areas due to high levels of melanin in...
  
  
• White matter
  White matter
  White matter is one of the two components of the central nervous system and consists mostly of myelinated axons. White matter tissue of the freshly cut brain appears pinkish white to the naked eye because myelin is composed largely of lipid tissue veined with capillaries. Its white color is due to...
  
  

External links