Editing Thalamus (section)

== Function ==
The thalamus has multiple functions, and is generally believed to act as a relay station, or [[hub (network science)|hub]], relaying information between different subcortical areas and the cerebral cortex.<ref>{{Cite book |title=Cognitive Neuroscience - The Biology of The Mind |last1=Gazzaniga |last2=Ivry |last3=Mangun |first1=Michael S. |first2=Richard B. |first3=George R. |publisher=W.W. Norton |year=2014 |isbn=978-0-393-91348-4 |location=New York |pages=[https://archive.org/details/cognitiveneurosc0000gazz/page/45 45] |url=https://archive.org/details/cognitiveneurosc0000gazz/page/45}}</ref> In particular, every sensory system (with the exception of the [[olfactory system]]) includes a thalamic nucleus that receives sensory signals and sends them to the associated primary cortical area.<ref>{{cite book |last1=Hall |first2=John E. |last2=Hall |first1=Michael E. |title=Guyton and Hall textbook of medical physiology |year=2021 |publisher=Elsevier |location=Philadelphia, PA |isbn=978-0-323-59712-8 |edition=14th |pages=682, 728}}</ref><ref>{{cite book |last1=Brodal |first1=Per |title=The Central Nervous System |publisher=Oxford University Press |location=New York |year= 2016 |edition=5th |isbn=978-0-19-022895-8 |page=314}}</ref>

For the visual system, for example, inputs from the [[retina]] are sent to the [[lateral geniculate nucleus]] of the thalamus, which in turn projects to the [[visual cortex]] in the [[occipital lobe]].<ref>{{cite journal |last1=Shin |first1=Lisa M |last2=Liberzon |first2=Israel |title=The Neurocircuitry of Fear, Stress, and Anxiety Disorders |journal=Neuropsychopharmacology |date=January 2010 |volume=35 |issue=1 |pages=169–191 |doi=10.1038/npp.2009.83 |pmid=19625997 |pmc=3055419}}</ref> Similarly the [[medial geniculate nucleus]] acts as a key [[Auditory system|auditory]] relay between the [[inferior colliculus]] of the [[midbrain]] and the [[primary auditory cortex]].{{Citation needed|date=October 2016}} The [[ventral posterior nucleus]] is a key [[somatosensory]] relay, which sends touch and [[proprioceptive]] information to the [[primary somatosensory cortex]].{{Citation needed|date=October 2016}} In rodents, proprioceptive information of head and whisker movements is integrated already at the thalamic level.<ref>{{Cite journal |last1=Oram |first1=Tess Baker |last2=Tenzer |first2=Alon |last3=Saraf-Sinik |first3=Inbar |last4=Yizhar |first4=Ofer |last5=Ahissar |first5=Ehud |date=2024-07-13 |title=Co-coding of head and whisker movements by both VPM and POm thalamic neurons |journal=Nature Communications |language=en |volume=15 |issue=1 |pages=5883 |doi=10.1038/s41467-024-50039-z |pmid=39003286 |pmc=11246487 |bibcode=2024NatCo..15.5883O |issn=2041-1723}}</ref>

The thalamus is believed to both process sensory information as well as relay it—each of the primary sensory relay areas receives strong feedback connections from the cerebral cortex.<ref>{{cite web |title=The thalamus, middleman of the brain, becomes a sensory conductor |publisher=The University of Chicago Medicine |url=https://www.uchicagomedicine.org/forefront/news/the-thalamus-middleman-of-the-brain-becomes-a-sensory-conductor |access-date=10 September 2020}}</ref>

The thalamus also plays an important role in regulating states of [[sleep]], and [[wakefulness]].<ref>{{cite journal |pmid=2839857 |year=1988 |last1=Steriade |first1=Mircea |last2=Llinás |first2=Rodolfo R. |title=The Functional States of the Thalamus and the Associated Neuronal Interplay |volume=68 |issue=3 |pages=649–742 |journal=Physiological Reviews |doi=10.1152/physrev.1988.68.3.649}}</ref> Thalamic nuclei have strong reciprocal connections with the cerebral cortex, forming [[thalamo-cortico-thalamic circuits]] that are believed to be involved with [[consciousness]].<ref>{{cite book |first1=Caroline |last1=Schnakers |first2=Steven |last2=Laureys |title=Coma and Disorders of Consciousness |date=2012 |publisher=Springer |location=London |isbn=978-1-447-12439-9 |page=143}}</ref><ref>{{cite journal |last1=Ward |first1=Lawrence M. |last2=Guevara |first2=Ramón |title=Qualia and phenomenal consciousness arise from the information structure of an electromagnetic field in the brain |journal=Frontiers in Human Neuroscience |date=July 4, 2022 |volume=16 |doi=10.3389/fnhum.2022.874241 |doi-access=free |pmid=35860400 |pmc=9289677}}</ref> The thalamus plays a major role in regulating arousal, the level of awareness, and activity. Damage to the thalamus can lead to permanent [[coma]].<ref>''The Neurology of Consciousness: Cognitive Neuroscience and Neuropathology'' {{ISBN|978-0-123-74168-4}} p. 10</ref>

The role of the thalamus in the more anterior [[pallidal]] and [[nigral]] territories in the [[basal ganglia]] system disturbances is recognized but still poorly understood. The contribution of the thalamus to vestibular or to [[tectal]] functions is almost ignored. The thalamus has been thought of as a "relay" that simply forwards signals to the cerebral cortex. Newer research suggests that thalamic function is more selective.<ref>{{cite web |first=Abigail W. |last=Leonard |date=August 17, 2006 |title=Your Brain Boots Up Like a Computer |url=http://www.livescience.com/980-brain-boots-computer.html |work=LiveScience}}</ref> Many different functions are linked to various regions of the thalamus. This is the case for many of the sensory systems (except for the olfactory system), such as the [[auditory system|auditory]], [[somatic sensory system|somatic]], [[visceral]], [[gustatory]] and [[visual system]]s where localized lesions provoke specific sensory deficits. A major role of the thalamus is support of motor and language systems, and much of the circuitry implicated for these systems is shared.

The thalamus is ''functionally connected'' to the [[hippocampus]]<ref>{{cite journal |pmid=11003270 |year=2000 |last1=Stein |first1=Thor |last2=Moritz |first2=Chad |last3=Quigley |first3=Michelle |last4=Cordes |first4=Dietmar |last5=Haughton |first5=Victor |last6=Meyerand |first6=Elizabeth |title=Functional Connectivity in the Thalamus and Hippocampus Studied with Functional MR Imaging |volume=21 |issue=8 |pages=1397–401 |journal=American Journal of Neuroradiology |pmc=7974059 |url=http://www.ajnr.org/cgi/pmidlookup?view=long&pmid=11003270}}</ref> as part of the extended hippocampal system at the thalamic anterior nuclei.<ref>{{cite journal |doi=10.1017/S0140525X99002034 |title=Episodic memory, amnesia, and the hippocampal–anterior thalamic axis |year=1999 |last1=Aggleton |first1=John P. |last2=Brown |first2=Malcolm W. |journal=Behavioral and Brain Sciences |volume=22 |issue=3 |pmid=11301518 |pages=425–44; discussion 444–89|s2cid=11258997 |url=http://orca.cf.ac.uk/34930/1/Aggleton%201999.pdf}}</ref> With respect to spatial memory and spatial sensory datum they are crucial for human episodic event memory.<ref>{{cite journal |doi=10.1111/j.1460-9568.2010.07251.x |title=Hippocampal-anterior thalamic pathways for memory: Uncovering a network of direct and indirect actions |year=2010 |last1=Aggleton |first1=John P. |last2=O'Mara |first2=Shane M. |last3=Vann |first3=Seralynne D. |last4=Wright |first4=Nick F. |last5=Tsanov |first5=Marian |last6=Erichsen |first6=Jonathan T. |journal=European Journal of Neuroscience |volume=31 |issue=12 |pages=2292–307 |pmid=20550571 |pmc=2936113}}</ref><ref>{{cite journal |doi=10.1016/S0896-6273(02)00830-9 |title=The Human Hippocampus and Spatial and Episodic Memory |year=2002 |last1=Burgess |first1=Neil |last2=Maguire |first2=Eleanor A |last3=O'Keefe |first3=John |journal=Neuron |volume=35 |issue=4 |pages=625–41 |pmid=12194864|s2cid=11989085 |doi-access=free}}</ref> The thalamic region's connection to the [[medial temporal lobe]] provides differentiation of the functioning of recollective and familiarity memory.<ref name=pmid21255590/>

The neuronal information processes necessary for motor control were proposed as a network involving the thalamus as a subcortical motor center.<ref>{{cite journal |doi=10.1146/annurev.ph.31.030169.002315 |title=Motor Mechanisms of the CNS: Cerebrocerebellar Interrelations |year=1969 |last1=Evarts |first1=E V |last2=Thach |first2=W T |journal=Annual Review of Physiology |volume=31 |pages=451–98 |pmid=4885774}}</ref> Through investigations of the anatomy of the brains of primates<ref>{{cite journal |pmid=2478593 |year=1989 |last1=Orioli |first1=PJ |last2=Strick |first2=PL |title=Cerebellar connections with the motor cortex and the arcuate premotor area: An analysis employing retrograde transneuronal transport of WGA-HRP |volume=288 |issue=4 |pages=612–26 |doi=10.1002/cne.902880408 |journal=The Journal of Comparative Neurology|s2cid=27155579}}</ref> the nature of the interconnected tissues of the [[cerebellum]] to the multiple motor cortices suggested that the thalamus fulfills a key function in providing the specific channels from the basal ganglia and cerebellum to the cortical motor areas.<ref>{{cite journal |vauthors=Asanuma C, Thach WT, Jones EG |title=Cytoarchitectonic delineation of the ventral lateral thalamic region in the monkey |journal=Brain Research |volume=286 |issue=3 |pages=219–35 |date=May 1983  |pmid=6850357 |doi=10.1016/0165-0173(83)90014-0|s2cid=25013002}}</ref><ref>{{cite journal |pmid=15703228 |year=2005 |last1=Kurata |first1=K |title=Activity properties and location of neurons in the motor thalamus that project to the cortical motor areas in monkeys |volume=94 |issue=1 |pages=550–66 |doi=10.1152/jn.01034.2004 |journal=Journal of Neurophysiology}}</ref> In an investigation of the [[saccade]] and [[Antisaccade task|antisaccade]]<ref>{{Cite web |url=http://www.optomotorik.de/blicken/anti-rev.htm |title=The Antisaccade - A Review of Basic Research and Clinical Studies |access-date=2012-02-10 |archive-date=2017-09-16 |archive-url=https://web.archive.org/web/20170916182657/http://www.optomotorik.de/blicken/anti-rev.htm |url-status=dead}}{{full citation needed|date=November 2012}}</ref> motor response in three monkeys, the thalamic regions were found to be involved in the generation of antisaccade eye-movement (that is, the ability to inhibit the reflexive jerking movement of the eyes in the direction of a presented stimulus).<ref>{{cite journal |pmid=20371831 |year=2010 |last1=Kunimatsu |first1=J |last2=Tanaka |first2=M |title=Roles of the primate motor thalamus in the generation of antisaccades |volume=30 |issue=14 |pages=5108–17 |doi=10.1523/JNEUROSCI.0406-10.2010 |pmc=6632795 |journal=Journal of Neuroscience|url=http://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/43986/1/JN30-14_5108-5117.pdf}}</ref>

Recent research suggests that the mediodorsal thalamus (MD) may play a broader role in cognition. Specifically, the mediodorsal thalamus may "amplify the connectivity (signaling strength) of just the circuits in the cortex appropriate for the current context and thereby contribute to the flexibility (of the mammalian brain) to make complex decisions by wiring the many associations on which decisions depend into weakly connected cortical circuits."<ref name=":0">{{Cite news|url=http://neurosciencenews.com/pfc-decision-making-6576/|title=New Role Discovered For Brain Region|date=2017-05-03|work=Neuroscience News|access-date=2017-12-03|language=en-US}}</ref> Researchers found that "enhancing MD activity magnified the ability of mice to "think,"<ref name=":0" /> driving down by more than 25 percent their error rate in deciding which conflicting sensory stimuli to follow to find the reward."<ref>{{cite journal |last1=Schmitt |first1=L. Ian |last2=Wimmer |first2=Ralf D. |last3=Nakajima |first3=Miho |last4=Happ |first4=Michael |last5=Mofakham |first5=Sima |last6=Halassa |first6=Michael M. |title=Thalamic amplification of cortical connectivity sustains attentional control |journal=Nature |date=May 2017 |volume=545 |issue=7653 |pages=219–223 |doi=10.1038/nature22073 |pmid=28467827 |pmc=5570520 |bibcode=2017Natur.545..219S}}</ref>