Editing Precuneus

{{Short description|Region of the parietal lobe of the brain}}

{{Infobox brain
| Name            = Precuneus
| Latin           = praecuneus
| Image           = Sobo 1909 624 - Precuneus.png
| Caption         = Medial surface of left cerebral hemisphere. (Precuneus visible at top left.) (Anterior to the right.)
| Image2          = Precuneus.png
| Caption2        = [[Sagittal plane|Sagittal]] MRI slice with the precuneus shown in red. (Anterior to the left.)
| IsPartOf        =
| Components      =
| Artery          =
| Vein            =
}}

In [[neuroanatomy]], the '''precuneus''' is the portion of the [[superior parietal lobule]] on the [[Anatomical terms of location#Medial_and_lateral|medial]] surface of each brain [[cerebral hemisphere|hemisphere]]. It is located in front of the [[cuneus]] (the upper portion of the [[occipital lobe]]). The precuneus is bounded in front by the [[marginal sulcus|marginal branch]] of the [[cingulate sulcus]], at the rear by the [[parieto-occipital sulcus]], and underneath by the [[subparietal sulcus]]. It is involved with [[episodic memory]], [[visuospatial]] processing, reflections upon [[Self (psychology)|self]], and aspects of [[consciousness]].

The location of the precuneus makes it difficult to study. Furthermore, it is rarely subject to isolated injury due to [[stroke]]s, or trauma such as gunshot wounds. This has resulted in it being "one of the less accurately mapped areas of the whole cortical surface".<ref name="Cavanna06"/>  While originally described as homogeneous by [[Korbinian Brodmann]], it is now appreciated to contain three subdivisions.<ref name="Margulies"/>

It is also known after [[Achille-Louis Foville]] as the ''quadrate lobule of Foville''.<ref name="Cavanna06">{{cite journal |vauthors=Cavanna A, Trimble M |title=The precuneus: a review of its functional anatomy and behavioural correlates |journal=Brain |volume=129 |issue=Pt 3 |pages=564–83 |year=2006 |pmid=16399806 |doi=10.1093/brain/awl004 |doi-access=free }}</ref><ref name="Cavanna"/><ref>Foville AL. (1844). Traité complêt de l’anatomie, de la physiologie et de la pathologie du système nerveux cérébro-spinal. Paris, France: Fortin, Masson</ref> The Latin form of {{lang|la|praecuneus}} was first used in 1868 and the English ''precuneus'' in 1879.<ref>[[Oxford English Dictionary]], ''Precuneus''.</ref>

== Structure ==
[[File:Precuneus connectivity new.gif|thumb|300px|Subdivisions of precuneus and posterior cingulate in the human based upon [[Default mode network|resting state]] functional connectivity.<ref name="Margulies"/>
{{Legend|#6367c5|Blue: Sensorimotor Anterior Region and its connections}}
{{Legend|#84b29c|Green: Cognitive/Associative Central Region}}
{{Legend|#c9ae73|Yellow: Visual Posterior Region}}
(The red color shows the [[posterior cingulate]] and its connections.)]]

The precuneus is located on the inside between the two [[cerebral hemisphere]]s in the rear region between the [[somatosensory|somatosensory cortex]] and forward of the [[cuneus]] (which contains the [[visual cortex]]). It is above the [[posterior cingulate]]. Following [[Korbinian Brodmann]] it has traditionally been considered a homogeneous structure and with limited distinction between it and the neighboring [[posterior cingulate]] area. Brodmann mapped it as the medial continuation of lateral parietal [[Brodmann area 7|area 7]].

[[Anterograde tracing|Axon tracing]] research on [[macaque monkey]]s has established that it consists of three subdivisions which now have been confirmed by [[fMRI]] upon  resting-state [[Functional neuroimaging|functional connectivity]] to also exist in [[human]]s (parallel fMRI research has also been done upon monkeys).<ref name="Margulies">{{cite journal |vauthors=Margulies DS, Vincent JL, Kelly C, Lohmann G, Uddin LQ, Biswal BB, Villringer A, Castellanos FX, Milham MP, Petrides M |title=Precuneus shares intrinsic functional architecture in humans and monkeys |journal=PNAS |year=2009 |doi=10.1073/pnas.0905314106 |pmid=19903877 |volume=106 |issue=47 |pages=20069–74 |pmc=2775700 |bibcode=2009PNAS..10620069M |doi-access=free }}</ref>

=== Subdivisions ===
;Sensorimotor Anterior Region
This occurs around the margin of the [[cingulate sulcus]]  ({{Legend inline|#6367c5}}blue in figure) and is connected with sensorimotor areas of the cerebral cortex such as the [[paracentral lobule]], [[supplementary motor area]], [[premotor cortex]], [[somatosensory area]] ([[Brodmann area 2]]), [[parietal operculum]] and [[insular cortex|insula]]. fMRI Research upon humans finds a connection with the caudalmost part of [[parahippocampus]] and [[superior temporal gyrus]]. No connections with the [[inferior parietal lobule]], [[prefrontal cortex]] nor [[primary motor cortex]].

;Cognitive/Associative Central Region
This occurs around the precuneal sulcus ({{Legend inline|#84b29c}}green in figure) and is connected with the [[inferior parietal lobule]] particularly the [[angular gyrus]] and prefrontal areas [[Brodmann area 10|10]], [[Brodmann area 46|46]] and [[Brodmann area 8|8]]. No connections exist with premotor, motor, or somatosensory areas. The areas with which it links are involved in [[executive functions]], [[working memory]] and [[motor planning]].

;Visual Posterior Region
This occurs along the parieto-occipital fissure ({{Legend inline|#c9ae73}}yellow in figure). This connects with visual areas in the [[cuneus]] and [[primary visual cortex]].

=== Subcortical connections ===
Below the cerebral cortex, the precuneus is connected  with the dorsalmost nuclei of the [[thalamus]], including the [[ventral lateral nucleus]], the central and anterior nuclei of the [[intralaminar nuclear group]],  and the lateral [[pulvinar nuclei|pulvinar]]. Other connections include the [[claustrum]], the dorsolateral [[caudate nucleus]], [[putamen]], and the [[zona incerta]].<ref name="Cavanna06"/><ref name="Cavanna"/> It also has links with the [[brainstem]] areas such as the [[pretectal area]], the [[superior colliculus]], the [[nucleus reticularis tegmenti pontis]], and the [[basis pontis]].<ref name="Cavanna06"/><ref name="Cavanna"/>

== Function ==
The [[mental imagery]] concerning the [[Self (psychology)|self]] has been located in the forward part of the precuneus with posterior areas being involved with [[episodic memory]].<ref>{{cite journal|last=Fletcher|first=P.C.|author2=Frith, C.D. |author3=Baker, S.C. |author4=Shallice, T. |author5=Frackowiak, R.S.J. |author6=Dolan, R.J. |title=The Mind's Eye--Precuneus Activation in Memory-Related Imagery|journal=NeuroImage|year=1995|volume=2|pages=195–200|pmid=9343602|doi=10.1006/nimg.1995.1025 |issue=3|hdl=21.11116/0000-0001-A200-7|s2cid=20334615|hdl-access=free}}</ref> Another area has been linked to [[visuospatial]] imagery. (It is not though clear how these—and the functions noted below—link with the above three subdivisions.)

The precuneus plays a role in itch sensations (there are many different types of itch) and their brain processing <ref>{{Cite journal | doi=10.1111/1346-8138.12956| pmid=26046307|title = Itch and brain| journal=The Journal of Dermatology| volume=42| issue=8| pages=761–767|year = 2015|last1 = Mochizuki|first1 = Hideki| last2=Kakigi| first2=Ryusuke| s2cid=42208021}}</ref> “‘We can’t [yet] pinpoint what the precuneus does in itch, but it’s uniquely activated with itch and not pain.’” <ref>Sutherland, S. 2016. When pain feels good. New Scientist 232(3101):37-38</ref>

=== Self ===
[[Functional imaging]] has linked the precuneus to the processes involved in [[self-consciousness]], such as reflective self-awareness, that involve rating one's own personality traits compared to those judged of other people.<ref>{{cite journal |vauthors=Kjaer TW, Nowak M, Lou HC | year = 2002 | title = Reflective self-awareness and conscious states: PET evidence for a common midline parietofrontal core | journal = NeuroImage | volume = 17 | issue = 2| pages = 1080–6 | doi = 10.1006/nimg.2002.1230 | pmid = 12377180 | s2cid = 23923373 | doi-access = free }}</ref><ref name="Lou">{{cite journal |vauthors=Lou HC, Luber B, Crupain M, Keenan JP, Nowak M, Kjaer TW, Sackeim HA, Lisanby SH |pmc=404216 | pmid = 15096584 |pages=6827–32 | year=2004 | title=Parietal cortex and representation of the mental Self. | volume=101 | issue=17 | doi=10.1073/pnas.0400049101 | journal=Proceedings of the National Academy of Sciences of the United States of America|bibcode=2004PNAS..101.6827L |doi-access=free }}</ref>

Electrical stimulation of the anterior portion can induce an [[out of body experience]].<ref>{{cite news |url=https://www.npr.org/2023/07/28/1190816885/this-sausage-shaped-part-of-your-brain-causes-out-of-body-experiences |title=This sausage-shaped part of your brain causes out-of-body experiences |author=Jon Hamilton |date=August 4, 2023 |publisher=NPR |work=Short Wave}}</ref>

=== Memory ===
The precuneus is involved in memory tasks, such as when people look at images and try to respond based on what they have remembered in regard to verbal questions about their spatial details.<ref>{{cite journal |vauthors=Wallentin M, Roepstorff A, Glover R, Burgess N | year = 2006 | title = Parallel memory systems for talking about location and age in precuneus, caudate and Broca's region | journal = NeuroImage | volume = 32 | issue = 4| pages = 1850–64 | doi = 10.1016/j.neuroimage.2006.05.002 | pmid = 16828565 | citeseerx = 10.1.1.326.8669 | s2cid = 10439632 }}</ref> It is involved with the left prefrontal cortex in the recall of [[episodic memories]]<ref>{{cite journal |vauthors=Lundstrom BN, Petersson KM, Andersson J, Johansson M, Fransson P, Ingvar M | year = 2003 | title = Isolating the retrieval of imagined pictures during episodic memory: activation of the left precuneus and left prefrontal cortex | journal = NeuroImage | volume = 20 | issue = 4| pages = 1934–43 | pmid = 14683699 | doi = 10.1016/j.neuroimage.2003.07.017 | hdl = 11858/00-001M-0000-0013-39A9-E | s2cid = 5953246 | hdl-access = free }}</ref><ref>{{cite journal |vauthors=Sadigh-Eteghad S, Majdi A, Farhoudi M, Talebi M, Mahmoudi J | year = 2014 | title = Different patterns of brain activation in normal aging and Alzheimer's disease from cognitional sight: meta analysis using activation likelihood estimation | journal = Journal of the Neurological Sciences | volume = 343| issue = 1| pages = 159–66 | pmid = 24950901| doi = 10.1016/j.jns.2014.05.066 | s2cid = 24359894 }}</ref> including past episodes related to the self.<ref name="Lou"/> The precuneus is also involved in [[Source amnesia|source memory]] (in which the "source" circumstances of a memory are recalled) with the left inferior prefrontal cortex: here its role is postulated to be providing rich episodic contextual associations used by the prefrontal cortex to select the correct past memory.<ref>{{cite journal |vauthors=Lundstrom BN, Ingvar M, Petersson KM | year = 2005 | title = The role of precuneus and left inferior frontal cortex during source memory episodic retrieval | journal = NeuroImage | volume = 27 | issue = 4| pages = 824–34 | pmid = 15982902 | doi = 10.1016/j.neuroimage.2005.05.008 | hdl = 11858/00-001M-0000-0013-3A7E-4 | s2cid = 8173843 | hdl-access = free }}</ref> In the recollection of memories, it has been postulated that the precuneus discerns whether  contextual information exists that can be useful for involving the aid of the [[hippocampus]].{{citation needed|date=June 2021}} Alternatively it has a different involvement when judging the familiarity as it decides whether the processing of perceptual features would be more useful.<ref name="Dörfel">{{cite journal |pmid = 1989556 | volume=51 | issue=2 | title=Delayed death from aortic root trauma |date=February 1991 |vauthors=Boruchow IB, Hutchins GM | journal=Ann. Thorac. Surg. | pages=317–9 | doi=10.1016/0003-4975(91)90815-8}}</ref> In this way the precuneus gets involved in diverse processes such as attention, episodic memory retrieval, working memory and conscious perception.<ref name="Dörfel"/>

=== Visuospatial ===
The precuneus has been suggested to be involved in directing attention in space both when an individual makes movements and when imaging or preparing them.<ref name="Cavanna06"/><ref>{{cite journal |vauthors=Kawashima R, Roland PE, O'Sullivan BT | year = 1995 | title = Functional anatomy of reaching and visuomotor learning: a positron emission tomography study | journal = Cereb Cortex | volume = 5 | issue = 2| pages = 111–22 | pmid = 7620288 | doi = 10.1093/cercor/5.2.111 }}</ref> It is involved in motor imagery and shifting attention between motor targets.<ref name="Cavanna06"/> It is also involved in [[motor coordination]] that requires shifting attention to different spatial locations.<ref>{{cite journal |vauthors=Wenderoth N, Debaere F, Sunaert S, Swinnen SP | year = 2005 | title = The role of anterior cingulate cortex and precuneus in the coordination of motor behaviour | journal = Eur J Neurosci | volume = 22 | issue = 1| pages = 235–46 | doi = 10.1111/j.1460-9568.2005.04176.x | pmid = 16029213 | s2cid = 25754084 }}</ref> It is also together with the dorsal [[premotor cortex]] involved in [[visuospatial]] mental operations (such as in a modified form of the game of [[Amidakuji]]). It is suggested that while the premotor area engages in the mental operation, the precuneus aids monitoring the success of that operation in terms of internally represented visual images.<ref>{{cite journal | vauthors = Oshio R, Tanaka S, Sadato N, Sokabe M, Hanakawa T, Honda M | year = 2010 | title = Differential effect of double-pulse TMS applied to dorsal premotor cortex and precuneus during internal operation of visuospatial information.| journal = NeuroImage | volume = 49 | issue = 1| pages = 1108–15 | pmid = 19632337 | doi=10.1016/j.neuroimage.2009.07.034| s2cid = 17788847 }}</ref>

The precuneus' role in mental imagery has been suggested to extend  to that of modeling other people's views. It is activated when a person takes a third-person versus first-person visual point of view.<ref>{{cite journal |vauthors=Vogeley K, May M, Ritzl A, Falkai P, Zilles K, Fink GR | year = 2004 | title = Neural correlates of first-person perspective as one constituent of human self-consciousness | journal = J Cogn Neurosci | volume = 16 | issue = 5| pages = 817–27 | pmid = 15200709 | doi = 10.1162/089892904970799 | s2cid = 17578549 }}</ref> Together with the [[superior frontal gyrus]] and [[orbitofrontal cortex]], the precuneus is activated when people make judgments that require understanding whether to act out of [[empathy]] and [[forgiveness]].<ref>{{cite journal |vauthors=Farrow TF, Zheng Y, Wilkinson ID, Spence SA, Deakin JF, Tarrier N, Griffiths PD, Woodruff PW | year = 2001 | title = Investigating the functional anatomy of empathy and forgiveness | journal = NeuroReport | volume = 12 | issue = 11| pages = 2433–8 | pmid = 11496124 | doi = 10.1097/00001756-200108080-00029 | s2cid = 34437619 }}</ref>

===Executive functions===
Precuneus is thought to be related to response inhibition.<ref>{{cite journal |vauthors=Marakshina J, Vartanov A, Buldakova N| year = 2018 | title = Effect of eye dominance on cognitive control| journal = European Proceedings of Social and Behavioral Sciences | series = The European Proceedings of Social and Behavioural Sciences | volume = 49 | pages = 402–408 | doi = 10.15405/epsbs.2018.11.02.43 | doi-access = free }}</ref>

===Consciousness===
It has been suggested that together with the posterior cingulate, the precuneus is "pivotal for conscious information processing".<ref name="Vogt">{{cite book | pmc=2679949 | pmid = 16186025 |vauthors=Vogt BA, Laureys S | year=2005 | chapter=Posterior cingulate, precuneal and retrosplenial cortices: cytology and components of the neural network correlates of consciousness | volume=150 | pages=205–17 | doi=10.1016/S0079-6123(05)50015-3 | series = Progress in Brain Research | isbn = 9780444518514 | title = The Boundaries of Consciousness: Neurobiology and Neuropathology }}</ref> The evidence for this link with [[consciousness]] comes from the effects of its disruption in [[epilepsy]], [[stroke|brain lesion]]s and [[vegetative state]].<ref name="Cavanna">{{cite journal | pmid = 17603406 | author=Cavanna AE | year = 2007 | title = The precuneus and consciousness | volume = 12 | issue = 7 | pages = 545–52 | journal = CNS Spectrums | doi = 10.1017/S1092852900021295 | s2cid=8068770 }}</ref><ref name="Vogt"/> Also, cerebral glucose metabolism is at its highest in these two areas during [[wakefulness]] but is most reduced in them during [[anesthesia]].<ref name="Cavanna"/><ref name="Vogt"/> In addition, it is one of the areas of the brain most deactivated during [[slow-wave sleep]] and [[rapid eye movement sleep]].<ref name="Cavanna"/>

Together with the prefrontal cortex, the precuneus, is more activated upon the learning of words briefly flashed when they are supraliminal (and so enter consciousness) than [[Subliminal message|subliminal]] (and so do not enter consciousness).<ref>{{cite journal |vauthors=Kjaer TW, Nowak M, Kjaer KW, Lou AR, Lou HC | year = 2001 | title = Precuneus-prefrontal activity during awareness of visual verbal stimuli | journal = Conscious. Cogn. | volume = 10 | issue = 3| pages = 356–65 | pmid = 11697869 |doi=10.1006/ccog.2001.0509| s2cid = 39449352 }}</ref>

===Default network===
It has been suggested to be the 'core node' or 'hub' of the [[default mode network]] that is activated during "resting consciousness" in which people do not engage intentionally in sensory or motor activity.<ref name="Cavanna"/> This involvement in the default network is suggested to underlie its role in [[self-consciousness]]. However its involvement in the default network has been questioned.<ref name="Margulies"/><ref>{{cite journal |vauthors=Buckner RL, Andrews-Hanna JR, Schacter DL | year = 2008 | title = The brain's default network: anatomy, function, and relevance to disease | journal = Ann N Y Acad Sci | volume = 1124 | issue = 1| pages = 1–38 | pmid = 18400922 | doi = 10.1196/annals.1440.011 | bibcode = 2008NYASA1124....1B | citeseerx = 10.1.1.689.6903 | s2cid = 3167595 }}</ref>  Though one of the authors raising these doubts noted "our findings in this regard should be treated as preliminary."<ref name="Margulies"/>  A later study in 2012 showed that only ventral precuneus is involved in the default network.<ref>{{cite journal | volume=59 | issue=4 | title=Functional connectivity mapping of the human precuneus by resting state fMRI |date=February 2012 |vauthors=Zhang S, Li CS | journal=NeuroImage | pages=3548–3562 | doi = 10.1016/j.neuroimage.2011.11.023 | pmid=22116037 | pmc=3288461}}</ref>

=== Parietal prefrontal central hub===
[[Olaf Sporns]] and Ed Bullmore have proposed that its functions link to its role as a central and well connected "[[small-world network]]" hub between parietal and prefrontal regions. 
<blockquote>These clusters or modules are interlinked by specialized hub regions, ensuring that overall path lengths across the network are short. Most studies identified [such] hubs among parietal and prefrontal regions, providing a potential explanation for their well-documented activation by many cognitive functions. Particularly notable is the prominent structural role of the precuneus, a region that is homologous to the highly connected posteromedial cortex in the macaque. The precuneus is involved in self-referential processing, imagery and memory, and its deactivation is associated with anaesthetic-induced loss of consciousness. An intriguing hypothesis suggests that these functional aspects can be explained on the basis of its high centrality in the cortical network.<ref>{{cite journal |vauthors=Bullmore E, Sporns O | year = 2009 | title = Complex brain networks: graph theoretical analysis of structural and functional systems | journal = Nat Rev Neurosci | volume = 10 | issue = 3| pages = 186–98 | pmid = 19190637 | doi = 10.1038/nrn2575 | s2cid = 205504722 }}</ref>
</blockquote>

==Correlation of grey matter volume and subjective happiness score==
A positive relationship has been found between the volume of [[grey matter]] in the right precuneus and the subject's subjective happiness score.<ref>{{Cite journal | doi=10.1038/srep16891| pmid=26586449| pmc=4653620| title=The structural neural substrate of subjective happiness| journal=Scientific Reports| volume=5| pages=16891| year=2015| last1=Sato| first1=Wataru| last2=Kochiyama| first2=Takanori| last3=Uono| first3=Shota| last4=Kubota| first4=Yasutaka| last5=Sawada| first5=Reiko| last6=Yoshimura| first6=Sayaka| last7=Toichi| first7=Motomi| bibcode=2015NatSR...516891S}}</ref>

==Impact of mindfulness==
A 6-week [[mindfulness]] based intervention was found to correlate with a significant [[grey matter]] increase within the precuneus.<ref>{{cite journal | pmc = 4306280 | pmid=25632405 | doi=10.17140/NOJ-1-106 | volume=1 | issue=1 | title=Brain Gray Matter Changes Associated with Mindfulness Meditation in Older Adults: An Exploratory Pilot Study using Voxel-based Morphometry | year=2014 | journal=Neuro | pages=23–26 |vauthors=Kurth F, Luders E, Wu B, Black DS }}</ref>

==Other animals==
The precuneus seems to be a recently expanded part of the brain, as in less developed [[primate]]s such as [[New world monkey]]s "the superior parietal and precuneate regions are poorly developed".<ref name="Cavanna06"/> It has been noted that "the precuneus is more highly developed (i.e. comprises a larger portion of the brain volume) in human beings than in non-human primates or other animals, has the most complex columnar cortical organization and is among the last regions to myelinate".<ref name="Cavanna06"/>

==Additional images==
<gallery>
 File:Precuneus animation.gif|Precuneus of left cerebral hemisphere (shown in red).
 File:Cerebral Gyri - Medial Surface1.png|Medial surface of left cerebral hemisphere. (Precuneus visible at top left.)
 File:Human brain inferior-medial view with marked Precuneus.JPG|Medial surface of left cerebral hemisphere. (Precuneus colored in red.)
 File:ParietCapts medial.png|Boundaries of precuneus are defined by the three sulci. (shown in red) {{ordered list |[[marginal sulcus|marginal branch]] of the [[cingulate sulcus]] |[[parieto-occipital sulcus]] |[[subparietal sulcus]]}} The area colored blue represents [[parietal lobe]].
 File:Cerebral Hemisphere Demonstration - Sanjoy Sanyal - Neuroscience Lab Fall 2013 (Cropped from 30m22s to 31m22s) Precuneus.webm|Human brain dissection video (1 min). Demonstrating the location of precuneus. ("SPL" in the video, means [[Superior parietal lobule]])
 File:Precuneus - DK ATLAS.png|Precuneus of right cerebral hemisphere.
 File:Precuneus coronal sections.gif|Precuneus highlighted in green on coronal T1 MRI images
 File:Precuneus sagittal sections.gif|Precuneus highlighted in green on sagittal T1 MRI images
 File:Precuneus transversal sections.gif|Precuneus highlighted in green on transversal T1 MRI images
</gallery>

== References ==
{{Reflist|2}}

== External links ==
{{Commons category|Precuneus}}
* {{UMichAtlas|n1a2p12}} - "Cerebral Hemisphere, Medial View"

{{Prosencephalon}}

{{Authority control}}

[[Category:Articles containing video clips]]
[[Category:Gyri]]
[[Category:Medial surface of cerebral hemisphere]]
[[Category:Parietal lobe]]