View source for Grey matter

{{short description|Areas of neuronal cell bodies in the brain}}
{{Other uses|Grey Matter (disambiguation){{!}}Grey Matter}}
{{Use British English|date=September 2019}}
{{Infobox anatomy
| Name        = Grey matter
| Latin       = substantia grisea
| Image       = spinal nerve.svg
| Caption     = The formation of the spinal nerve from the dorsal and ventral roots (with grey matter labelled at centre right).
| Width       =
| Image2      = Grey matter and white matter - very high mag.jpg
| Caption2    = [[Micrograph]] showing grey matter, with the characteristic [[neuron|neuronal cell bodies]] (dark shade of pink), and [[white matter]] with its characteristic fine meshwork-like appearance (left of image; lighter shade of pink). [[HPS stain]].
| Precursor   =
| System      =
| Artery      =
| Vein        =
| Nerve       =
| Lymph       =
}}

'''Grey matter''' ('''gray matter''' in [[American English]]) is a major component of the [[central nervous system]], consisting of [[neuron]]al [[Soma (biology)|cell bodies]], [[neuropil]] ([[dendrite]]s and unmyelinated [[axon]]s), [[Glia|glial cells]] ([[astrocyte]]s and [[oligodendrocyte]]s), [[synapse]]s, and [[Capillary|capillaries]]. Grey matter is distinguished from [[white matter]] in that it contains numerous cell bodies and relatively few myelinated axons, while white matter contains relatively few cell bodies and is composed chiefly of long-range myelinated axons.<ref name="Purves" >{{cite book | last1 = Purves | first1 = Dale | first2 = George J. | last2 = Augustine | first3 = David | last3 = Fitzpatrick | first4 = William C. | last4 = Hall | first5 = AS | last5 = LaMantia| first6 = James O. | last6 = McNamara | first7 = Leonard E. | last7 = White | name-list-style = vanc | title = Neuroscience | edition = 4th | publisher = Sinauer Associates | pages = 15–16 | year = 2008  | isbn = 978-0-87893-697-7 }}</ref> The colour difference arises mainly from the whiteness of [[myelin]]. In living tissue, grey matter actually has a very light grey colour with yellowish or pinkish hues, which come from capillary blood vessels and neuronal cell bodies.<ref>{{cite book|last1=Kolb|first1=Bryan | first2 =Ian Q.| last2 =Whishaw | name-list-style = vanc |title=Fundamentals of human neuropsychology|date=2003|publisher=Worth Publishing|location=New York|isbn=978-0-7167-5300-1|edition=5th| page = 49 }}</ref>

== Structure ==
Grey matter refers to unmyelinated [[neuron]]s and other cells of the [[central nervous system]]. It is present in the [[brain]], [[brainstem]] and [[cerebellum]], and present throughout the [[spinal cord]].

Grey matter is distributed at the surface of the [[cerebral hemisphere]]s ([[cerebral cortex]]) and of the cerebellum ([[cerebellar cortex]]), as well as in the depths of the cerebrum (the [[thalamus]]; [[hypothalamus]]; [[subthalamus]], [[basal ganglia]] – [[putamen]], [[globus pallidus]] and [[nucleus accumbens]]; as well as the [[septal nuclei]]), cerebellum (deep cerebellar nuclei – the [[dentate nucleus|dentate nuclei]], [[globose nucleus]], [[emboliform nucleus]], and [[fastigial nucleus]]), and [[brainstem]] (the [[substantia nigra]], [[red nucleus]], [[olivary body|olivary nuclei]], and [[cranial nerve nuclei]]).

Grey matter in the spinal cord is known as the [[grey column]] which travels down the spinal cord distributed in three grey columns that are presented in an "H" shape. The forward-facing column is the [[anterior grey column]], the rear-facing one is the [[posterior grey column]] and the interlinking one is the [[lateral grey column]]. The grey matter on the left and right side is connected by the [[gray commissure|grey commissure]]. The grey matter in the spinal cord consists of [[spinal interneuron|interneuron]]s, as well as the [[Soma (biology)|cell bodies]] of [[Projection fiber|projection neurons]].

<gallery>
File:Cervical_vertebra_english.png|Cross-section of a spinal [[vertebra]] with the spinal cord in the centre (and grey matter labelled).
File:Medulla spinalis - Section - English.svg|Cross-section of [[spinal cord]] with the grey matter labelled.
</gallery>

Grey matter undergoes development and growth throughout childhood and adolescence.<ref>{{cite journal | vauthors = Sowell ER, Thompson PM, Tessner KD, Toga AW | title = Mapping continued brain growth and gray matter density reduction in dorsal frontal cortex: Inverse relationships during postadolescent brain maturation | journal = The Journal of Neuroscience | volume = 21 | issue = 22 | pages = 8819–29 | date = November 2001 | pmid = 11698594 | pmc = 6762261 | doi = 10.1523/JNEUROSCI.21-22-08819.2001 }}</ref> Recent studies using cross-sectional neuroimaging have shown that by around the age of 8 the volume of grey matter begins to decrease.<ref name = "Gennatas_2017">{{cite journal | vauthors = Gennatas ED, Avants BB, Wolf DH, Satterthwaite TD, Ruparel K, Ciric R, Hakonarson H, Gur RE, Gur RC | title = Age-Related Effects and Sex Differences in Gray Matter Density, Volume, Mass, and Cortical Thickness from Childhood to Young Adulthood | journal = The Journal of Neuroscience | volume = 37 | issue = 20 | pages = 5065–5073 | date = May 2017 | pmid = 28432144 | pmc = 5444192 | doi = 10.1523/JNEUROSCI.3550-16.2017 }}</ref> However, the density of grey matter appears to increase as a child develops into early adulthood.<ref name = "Gennatas_2017" /> Males tend to exhibit grey matter of increased volume but lower density than that of females.<ref>{{cite journal |last1=Luders |first1=Eileen |last2=Gaser |first2=Christian |last3=Narr |first3=Katherine L. |last4=Toga |first4=Arthur W. |title=Why Sex Matters: Brain Size Independent Differences in Gray Matter Distributions between Men and Women |journal=The Journal of Neuroscience |date=11 November 2009 |volume=29 |issue=45 |pages=14265–14270 |doi=10.1523/JNEUROSCI.2261-09.2009 |pmid=19906974 |pmc=3110817 }}</ref>

== Function ==
Grey matter contains most of the brain's neuronal cell bodies.<ref>{{cite journal | vauthors = Miller AK, Alston RL, Corsellis JA | title = Variation with age in the volumes of grey and white matter in the cerebral hemispheres of man: measurements with an image analyser | journal = Neuropathology and Applied Neurobiology | volume = 6 | issue = 2 | pages = 119–32 | year = 1980 | pmid = 7374914 | doi = 10.1111/j.1365-2990.1980.tb00283.x | s2cid = 23201991 }}</ref> 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.

The grey matter in the [[spinal cord]] is split into three grey columns:
* The [[anterior grey column]] contains [[motor neuron]]s. These [[synapse]] with interneurons and the [[axon]]s of cells that have travelled down the [[pyramidal tract]]. These cells are responsible for the movement of muscles.
* The [[posterior grey column]] contains the points where [[sensory neuron]]s synapse. These receive sensory information from the body, including [[fine touch]], [[proprioception]], and [[vibration]]. This information is sent from receptors of the skin, bones, and joints through sensory neurons whose cell bodies lie in the dorsal root ganglion. This information is then transmitted in axons up the spinal cord in spinal tracts, including the [[dorsal column-medial lemniscus tract]] and the [[spinothalamic tract]].
* The [[lateral grey column]] is the third column of the spinal cord.

The grey matter of the spinal cord can be divided into different layers, called [[Rexed laminae]]. These describe, in general, the purpose of the cells within the grey matter of the spinal cord at a particular location.

<gallery>
File:Anatomy and physiology of animals A reflex arc.jpg|[[Interneuron]]s present in the grey matter of the spinal cord
File:Medulla spinalis - Substantia grisea - English.svg|[[Rexed laminae]] groups the grey matter in the spinal cord according to its function.
</gallery>

==Clinical significance==
High [[alcohol consumption]] has been correlated with significant reductions in grey matter volume.<ref>{{cite journal | vauthors = Yang X, Tian F, Zhang H, Zeng J, Chen T, Wang S, Jia Z, Gong Q | title = Cortical and subcortical gray matter shrinkage in alcohol-use disorders: a voxel-based meta-analysis | journal = Neuroscience and Biobehavioral Reviews | volume = 66 | pages = 92–103 | date = July 2016 | pmid = 27108216 | doi = 10.1016/j.neubiorev.2016.03.034 | s2cid = 19928689 }}</ref><ref>{{cite journal | vauthors = Xiao P, Dai Z, Zhong J, Zhu Y, Shi H, Pan P | title = Regional gray matter deficits in alcohol dependence: A meta-analysis of voxel-based morphometry studies | journal = Drug and Alcohol Dependence | volume = 153 | pages = 22–8 | date = August 2015 | pmid = 26072220 | doi = 10.1016/j.drugalcdep.2015.05.030 }}</ref> Short-term [[cannabis]] use (30 days) is not correlated with changes in [[white matter|white]] or grey matter.<ref>{{cite journal | vauthors = Thayer RE, YorkWilliams S, Karoly HC, Sabbineni A, Ewing SF, Bryan AD, Hutchison KE | title = Structural neuroimaging correlates of alcohol and cannabis use in adolescents and adults | journal = Addiction | volume = 112 | issue = 12 | pages = 2144–2154 | date = December 2017 | pmid = 28646566 | pmc = 5673530 | doi = 10.1111/add.13923 }}</ref> However, several cross-sectional studies have shown that repeated long-term cannabis use is associated with smaller grey matter volumes in the [[hippocampus]], [[amygdala]], medial [[temporal cortex]], and [[prefrontal cortex]], with increased grey matter volume in the cerebellum.<ref>{{cite journal | vauthors = Lorenzetti V, Lubman DI, Whittle S, Solowij N, Yücel M | title = Structural MRI findings in long-term cannabis users: what do we know? | journal = Substance Use & Misuse | volume = 45 | issue = 11 | pages = 1787–808 | date = September 2010 | pmid = 20590400 | doi = 10.3109/10826084.2010.482443 | s2cid = 22127231 }}</ref><ref>{{cite journal | vauthors = Matochik JA, Eldreth DA, Cadet JL, Bolla KI | title = Altered brain tissue composition in heavy marijuana users | journal = Drug and Alcohol Dependence | volume = 77 | issue = 1 | pages = 23–30 | date = January 2005 | pmid = 15607838 | doi = 10.1016/j.drugalcdep.2004.06.011 }}</ref><ref>{{cite journal | vauthors = Yücel M, Solowij N, Respondek C, Whittle S, Fornito A, Pantelis C, Lubman DI | title = Regional brain abnormalities associated with long-term heavy cannabis use | journal = Archives of General Psychiatry | volume = 65 | issue = 6 | pages = 694–701 | date = June 2008 | pmid = 18519827 | doi = 10.1001/archpsyc.65.6.694 | doi-access = free }}</ref> Long-term cannabis use is also associated with alterations in white matter integrity in an age-dependent manner,<ref>{{cite journal | vauthors = Jakabek D, Yücel M, Lorenzetti V, Solowij N | title = An MRI study of white matter tract integrity in regular cannabis users: effects of cannabis use and age | journal = Psychopharmacology | volume = 233 | issue = 19–20 | pages = 3627–37 | date = October 2016 | pmid = 27503373 | doi = 10.1007/s00213-016-4398-3 | s2cid = 5968884 | url = http://ro.uow.edu.au/ihmri/904 }}</ref> with heavy cannabis use during adolescence and early adulthood associated with the greatest amount of change.<ref>{{cite journal | vauthors = Becker MP, Collins PF, Lim KO, Muetzel RL, Luciana M | title = Longitudinal changes in white matter microstructure after heavy cannabis use | journal = Developmental Cognitive Neuroscience | volume = 16 | pages = 23–35 | date = December 2015 | pmid = 26602958 | pmc = 4691379 | doi = 10.1016/j.dcn.2015.10.004 }}</ref>

Meditation has been shown to change grey matter structure.<ref name=pmid25632405>{{cite journal | vauthors = Kurth F, Luders E, Wu B, Black DS | title = Brain Gray Matter Changes Associated with Mindfulness Meditation in Older Adults: An Exploratory Pilot Study using Voxel-based Morphometry | journal = Neuro | volume = 1 | issue = 1 | pages = 23–26 | year = 2014 | pmid = 25632405 | pmc = 4306280 | doi = 10.17140/NOJ-1-106 }}</ref><ref>{{cite journal | vauthors = Hölzel BK, Carmody J, Vangel M, Congleton C, Yerramsetti SM, Gard T, Lazar SW | title = Mindfulness practice leads to increases in regional brain gray matter density | journal = Psychiatry Research | volume = 191 | issue = 1 | pages = 36–43 | date = January 2011 | pmid = 21071182 | pmc = 3004979 | doi = 10.1016/j.pscychresns.2010.08.006 }}</ref><ref>{{cite journal | vauthors = Kurth F, MacKenzie-Graham A, Toga AW, Luders E | title = Shifting brain asymmetry: the link between meditation and structural lateralization | journal = Social Cognitive and Affective Neuroscience | volume = 10 | issue = 1 | pages = 55–61 | date = January 2015 | pmid = 24643652 | pmc = 4994843 | doi = 10.1093/scan/nsu029 }}</ref><ref name="Fox et al 2014">{{cite journal | vauthors = Fox KC, Nijeboer S, Dixon ML, Floman JL, Ellamil M, Rumak SP, Sedlmeier P, Christoff K | title = Is meditation associated with altered brain structure? A systematic review and meta-analysis of morphometric neuroimaging in meditation practitioners | journal = Neuroscience and Biobehavioral Reviews | volume = 43 | pages = 48–73 | date = June 2014 | pmid = 24705269 | doi = 10.1016/j.neubiorev.2014.03.016 | s2cid = 207090878 }}</ref><ref name=pmid19776221>{{cite journal | vauthors = Hölzel BK, Carmody J, Evans KC, Hoge EA, Dusek JA, Morgan L, Pitman RK, Lazar SW | title = Stress reduction correlates with structural changes in the amygdala | journal = Social Cognitive and Affective Neuroscience | volume = 5 | issue = 1 | pages = 11–7 | date = March 2010 | pmid = 19776221 | pmc = 2840837 | doi = 10.1093/scan/nsp034 }}</ref>

Habitual playing of action video games has been reported to promote a reduction of grey matter in the hippocampus while 3D platformer games have been reported to increase grey matter in the hippocampus.<ref>{{cite journal |last1=West |first1=Greg L. |last2=Drisdelle |first2=Brandi Lee |last3=Konishi |first3=Kyoko |last4=Jackson |first4=Jonathan |last5=Jolicoeur |first5=Pierre |last6=Bohbot |first6=Veronique D. |title=Habitual action video game playing is associated with caudate nucleus-dependent navigational strategies |journal=Proceedings of the Royal Society B: Biological Sciences |date=7 June 2015 |volume=282 |issue=1808 |article-number=20142952 |doi=10.1098/rspb.2014.2952 |pmid=25994669 |pmc=4455792}}
* {{cite press release |date=2017-08-07 |title=Playing action video games can actually harm your brain |publisher=Université de Montréal |url=https://nouvelles.umontreal.ca/en/article/2017/08/07/playing-action-video-games-can-actually-harm-your-brain/}}</ref><ref>{{cite web|url=http://qz.com/1050472/video-games-can-either-grow-or-shrink-part-of-your-brain-depending-on-how-you-play|title=Video games can either grow or shrink part of your brain, depending on how you play|first=Keith|last=Collins | name-list-style = vanc |website=qz.com|date=10 August 2017 |access-date=5 May 2018|url-status=live|archive-url=https://web.archive.org/web/20180414092101/https://qz.com/1050472/video-games-can-either-grow-or-shrink-part-of-your-brain-depending-on-how-you-play/|archive-date=14 April 2018}}</ref><ref>{{cite journal | vauthors = West GL, Zendel BR, Konishi K, Benady-Chorney J, Bohbot VD, Peretz I, Belleville S | title = Playing Super Mario 64 increases hippocampal grey matter in older adults | journal = PLOS ONE | volume = 12 | issue = 12 | article-number = e0187779 | date = 5 May 2018 | pmc = 5718432 | doi = 10.1371/journal.pone.0187779 | pmid = 29211727 | doi-access = free }}</ref>

Women and men with equivalent IQ scores have differing proportions of grey to white matter in cortical brain regions associated with intelligence.<ref>{{cite journal|title=The neuroanatomy of general intelligence: sex matters.|journal=NeuroImage|vauthors=Haier RJ, Jung RE, Yeo RA, Head K, Alkire MT|date=March 2005|volume=25|issue=1|pages=320–7|pmid=15734366|doi=10.1016/j.neuroimage.2004.11.019|s2cid=4127512}}</ref>

Pregnancy renders substantial changes in brain structure, primarily reductions in grey matter volume in regions subserving social cognition. Grey matter reductions endure for at least 2 years post-pregnancy.<ref>{{cite journal | vauthors = Hoekzema E, Barba-Müller E, Pozzobon C, Picado M, Lucco F, García-García D, Soliva JC, Tobeña A, Desco M, Crone EA, Ballesteros A, Carmona S, Vilarroya O | title = Pregnancy leads to long-lasting changes in human brain structure | journal = Nature Neuroscience | volume = 20 | issue = 2 | pages = 287–296 | date = February 2017 | pmid = 27991897 | doi = 10.1038/nn.4458 | ref = Hoekzema, E., et al. | hdl = 1887/57549 | s2cid = 4113669 | hdl-access = free }}</ref> The profile of brain changes is comparable to that taking place during adolescence, a hormonally similar transitional period of life.<ref>{{cite journal | vauthors = Carmona S, Martínez-García M, Paternina-Die M, Barba-Müller E, Wierenga LM, Alemán-Gómez Y, Cortizo R, Pozzobon C, Picado M, Lucco F, García-García D, Soliva JC, Tobeña A, Peper JS, Crone EA, Ballesteros A, Vilarroya O, Desco M, Hoekzema E | title = Pregnancy and adolescence entail similar neuroanatomical adaptations: A comparative analysis of cerebralmorphometric changes | journal = Hum Brain Mapp | volume = 40 | issue = 7 | pages = 2143–2152 | date = January 2019 | pmid = 30663172 | doi = 10.1002/hbm.24513| pmc = 6865685 | doi-access = free }}</ref>

==History==

===Etymology===
In the current edition<ref name="FCAT">Federative Committee on Anatomical Terminology (FCAT) (1998). ''Terminologia Anatomica''. Stuttgart: Thieme{{page needed|date=April 2020}}</ref> 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]].<ref name="Triepel1910b">{{cite book | vauthors = Triepel H | year = 1910 | title = Die anatomischen Namen. Ihre Ableitung und Aussprache. Mit einem Anhang: Biographische Notizen | edition = 3rd | location = Wiesbaden | publisher = Verlag J.F. Bergmann }}{{page needed|date=April 2020}}</ref> The adjective ''grisea'' is derived from the [[French language|French]] word for grey, ''gris''.<ref name="Triepel1910b"/> Alternative designations like ''substantia cana''<ref name="Triepel1910a">{{cite book | vauthors = Triepel H | year = 1910  | title = Nomina Anatomica. Mit Unterstützung von Fachphilologen | location = Wiesbaden | publisher = Verlag J.F. Bergmann }}{{page needed|date=April 2020}}</ref> and ''substantia cinerea''<ref name="Schreger">{{cite book | vauthors = Schreger CH | year = 1805 | chapter = Synonymia anatomica. Synonymik der anatomischen Nomenclatur | veditors = Fürth | title =  Bureau für Literatur }}{{page needed|date=April 2020}}</ref> are being used alternatively. The adjective ''cana'', attested in classical Latin,<ref name="Lewis & Short">{{cite book | vauthors = Lewis CT, Short C | year = 1879 | title = A Latin dictionary founded on Andrews' edition of Freund's Latin dictionary. | location = Oxford | publisher = Clarendon Press }}{{page needed|date=April 2020}}</ref> can mean ''grey'',<ref name="Triepel1910b"/> or ''greyish white''.<ref name=Stearn1983>{{cite book | vauthors = Stearn WT | year = 1983 | title = Botanical Latin. History, grammar, syntax, terminology and vocabulary. | edition = 3rd | publisher = Newton Abbot | location = London | veditors = Charles D }}{{page needed|date=April 2020}}</ref> The classical Latin ''cinerea'' means ''ash-coloured''.<ref name="Lewis & Short"/>

==Additional images==
<gallery>
 Image:Human brain right dissected lateral view description.JPG |Human brain right dissected lateral view
 Image:Gray678.png|Schematic representation of the chief ganglionic categories (I to V).
</gallery>

== See also ==
* [[Gray matter heterotopia|Grey matter heterotopia]]

== References ==
{{Reflist}}

== External links ==
* {{cite web|last1=May 2010 |first1=Stephanie Pappas |title=Why Is Gray Matter Gray? |url=https://www.livescience.com/32605-why-is-gray-matter-gray.html |work=Live Science |date=24 May 2010 }}

{{Nervous tissue}}
{{Spinal cord}}
{{Cerebral cortex}}
{{Authority control}}

{{DEFAULTSORT:Grey Matter}}
[[Category:Neuroanatomy]]
[[Category:Central nervous system]]