Editing Subthalamic nucleus (section)

==Physiology==
[[File:Basal ganglia circuits.svg|thumb|320px|Anatomical overview of the main circuits of the [[basal ganglia]]. Subthalamic nucleus is shown in red. Picture shows 2 coronal slices that have been superimposed to include the involved basal ganglia structures. + and - signs at the point of the arrows indicate respectively whether the pathway is excitatory or inhibitory in effect. {{color|green|Green arrows}} refer to excitatory [[:en:Glutamic acid|glutamatergic]] pathways, {{color|red|red arrows}} refer to inhibitory [[:en:gamma-Aminobutyric acid|GABAergic]] pathways and {{color|turquoise|turquoise arrows}} refer to [[:en:dopamine|dopaminergic]] pathways that are excitatory on the direct pathway and inhibitory on the indirect pathway.]]

===Subthalamic nucleus===
The first intracellular electrical recordings of subthalamic neurons were performed using sharp electrodes in a rat slice preparation.{{Citation needed|date=May 2010}}  In these recordings three key observations were made, all three of which have dominated subsequent reports of subthalamic firing properties. The first observation was that, in the absence of current injection or synaptic stimulation, the majority of cells were spontaneously firing. The second observation is that these cells are capable of transiently firing at very high frequencies.   The third observation concerns non-linear behaviors when cells are transiently depolarized after being hyperpolarized below –65mV. They are then able to engage voltage-gated calcium and sodium currents to fire bursts of action potentials.

Several recent studies have focused on the autonomous pacemaking ability of subthalamic neurons. These cells are often referred to as "fast-spiking pacemakers",<ref>{{cite journal | vauthors = Surmeier DJ, Mercer JN, Chan CS | title = Autonomous pacemakers in the basal ganglia: who needs excitatory synapses anyway? | journal = Current Opinion in Neurobiology | volume = 15 | issue = 3 | pages = 312–318 | date = June 2005 | pmid = 15916893 | doi = 10.1016/j.conb.2005.05.007 | s2cid = 42900941 | author-link1 = D. James Surmeier }}</ref> since they can generate spontaneous [[action potential]]s at rates of 80 to 90&nbsp;Hz in primates.

Oscillatory and synchronous activity<ref>{{cite journal | vauthors = Levy R, Hutchison WD, Lozano AM, Dostrovsky JO | title = High-frequency synchronization of neuronal activity in the subthalamic nucleus of parkinsonian patients with limb tremor | journal = The Journal of Neuroscience | volume = 20 | issue = 20 | pages = 7766–7775 | date = October 2000 | pmid = 11027240 | pmc = 6772896 | doi = 10.1523/JNEUROSCI.20-20-07766.2000 }}</ref><ref>{{cite journal | vauthors = Lintas A, Silkis IG, Albéri L, Villa AE | title = Dopamine deficiency increases synchronized activity in the rat subthalamic nucleus | journal = Brain Research | volume = 1434 | issue = 3 | pages = 142–151 | date = January 2012 | pmid = 21959175 | doi = 10.1016/j.brainres.2011.09.005 | s2cid = 14636489 | url = https://inserm.hal.science/inserm-00851266/file/Lintas_2012_Dopamine_Deficiency_AA.pdf }}</ref> is likely to be a typical pattern of discharge in subthalamic neurons recorded from patients and animal models characterized by the loss of dopaminergic cells in the [[substantia nigra pars compacta]], which is the principal pathology that underlies [[Parkinson's disease]].

=== Lateropallido-subthalamic system===
Strong reciprocal connections link the subthalamic nucleus and the external segment of the [[globus pallidus]]. Both are fast-spiking pacemakers. Together, they are thought to constitute the "central pacemaker of the basal ganglia"<ref>{{cite journal | vauthors = Plenz D, Kital ST | title = A basal ganglia pacemaker formed by the subthalamic nucleus and external globus pallidus | journal = Nature | volume = 400 | issue = 6745 | pages = 677–682 | date = August 1999 | pmid = 10458164 | doi = 10.1038/23281 | s2cid = 4356230 | bibcode = 1999Natur.400..677P }}</ref> with synchronous bursts.

The connection of the lateral pallidum with the subthalamic nucleus is also the one in the [[basal ganglia]] system where the reduction between emitter/receiving elements is likely the strongest. In terms of volume, in humans, the lateral pallidum measures 808&nbsp;mm<sup>3</sup>, the subthalamic nucleus only 158&nbsp;mm<sup>3</sup>.<ref>{{cite journal | vauthors = Yelnik J | title = Functional anatomy of the basal ganglia | journal = Movement Disorders | volume = 17 | issue = Suppl. 3 | pages = S15–S21 | year = 2002 | pmid = 11948751 | doi = 10.1002/mds.10138 | s2cid = 40925638 }}</ref> This translated in numbers of neurons represents a strong compression with loss of map precision.

Some axons from the lateral pallidum go to the striatum.<ref>{{cite journal | vauthors = Sato F, Lavallée P, Lévesque M, Parent A | title = Single-axon tracing study of neurons of the external segment of the globus pallidus in primate | journal = The Journal of Comparative Neurology | volume = 417 | issue = 1 | pages = 17–31 | date = January 2000 | pmid = 10660885 | doi = 10.1002/(SICI)1096-9861(20000131)417:1<17::AID-CNE2>3.0.CO;2-I | s2cid = 84665164 }}</ref> The activity of the medial pallidum is influenced by afferences from the lateral pallidum and from the subthalamic nucleus.<ref>{{cite journal | vauthors = Smith Y, Wichmann T, DeLong MR | title = Synaptic innervation of neurones in the internal pallidal segment by the subthalamic nucleus and the external pallidum in monkeys | journal = The Journal of Comparative Neurology | volume = 343 | issue = 2 | pages = 297–318 | date = May 1994 | pmid = 8027445 | doi = 10.1002/cne.903430209 | s2cid = 24968074 }}</ref> The same for the [[substantia nigra pars reticulata]].<ref name=Smith1990 /> The subthalamic nucleus  sends axons to another regulator: the pedunculo-pontine complex (id).

The lateropallido-subthalamic system is thought to play a key role in the generation of the patterns of activity seen in [[Parkinson's disease]].<ref>{{cite journal | vauthors = Bevan MD, Magill PJ, Terman D, Bolam JP, Wilson CJ | title = Move to the rhythm: oscillations in the subthalamic nucleus-external globus pallidus network | journal = Trends in Neurosciences | volume = 25 | issue = 10 | pages = 525–531 | date = October 2002 | pmid = 12220881 | doi = 10.1016/S0166-2236(02)02235-X | s2cid = 8127062 }}</ref>