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Encyclopedia > Subthalamic nucleus
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Coronal slices of human brain showing the basal ganglia, globus pallidus: external segment (GPe), subthalamic nucleus (STN), globus pallidus: internal segment (GPi), and substantia nigra (SN).

The subthalamic nucleus is a small lens-shaped nucleus in the brain where it is a part of the basal ganglia system. As suggested by its name, the subthalamic nucleus is located ventral to the thalamus. It is also dorsal to the substantia nigra and medial to the internal capsule. It was first described by Jules Bernard Luys in 1865[1], and the term corpus Luysi or Luys' body is still sometimes used. Image File history File links Basal-ganglia-coronal-sections-large. ... Image File history File links Basal-ganglia-coronal-sections-large. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... The globus pallidus (Latin for pale body) is a sub-cortical structure in the brain. ... The globus pallidus (Latin for pale body) is a sub-cortical structure in the brain. ... The substantia nigra (Latin for black substance) is a portion of the midbrain thought to be involved in certain aspects of movement and attention. ... In neuroanatomy, a nucleus is a central nervous system structure that is composed mainly of gray matter, and which acts as a hub or transit point for electrical signals in a single neural subsystem. ... Comparative brain sizes In animals, the brain, or encephalon (Greek for in the head), is the control center of the central nervous system. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... In human and zoological anatomy (sometimes called zootomy), several terms are used to describe the location of organs and other structures in the body of bilateral animals. ... Please wikify (format) this article as suggested in the Guide to layout and the Manual of Style. ... The internal capsule is an area of white matter in the brain that separates the caudate nucleus and the thalamus from the lenticular nucleus. ... Jules Bernard Luys (1828–1897) was a French neurologist who made important contributions to the fields of neuroanatomy and neuropsychiatry. ...

Contents


Anatomy

Structure

The principal type of neuron found in the subthalamic nucleus have rather long dendrites . The dendritic arborizations are elipsoid, replicating in smaller dimension the shape of the nucleus[2]. The dimensions of these arborizations (1200,600 and 300 μm) are similar across many species—including rat, cat, monkey and man—which is unusual. However, the number of neurons increases across evolution as well as the external dimensions of the nucleus. These principal neurons are glutamatergic, which give them a particular functional position in the basal ganglia system. In humans there are also a small number (about 7.5%) of GABAergic interneurons that participate in the local circuitry[3]. Drawing by Santiago Ramón y Cajal of cells in the pigeon cerebellum. ... The term Dendrite stems from the Greek word dendron (literally “tree”), and typically refers to the branched projections of a neuron that act to conduct the electrical stimulation received from other cells to and from the cell body, or soma of the neuron from which the dendrites project. ... Glutamic acid or glutamate (the anionic form of glutamic acid) is one of the 20 most common natural amino acids. ... Chemical structure of GABA Gamma-aminobutyric acid (GABA) is a neurotransmitter in widely divergent species. ... An interneuron (also called relay neuron or association neuron) is a neuron that communicates only to other neurons. ...


Afferent axons

The subthalamic nucleus receives its main input from the external segment of the globus pallidus (84.2% of its axons[4]) through the ansa lenticularis. This afference is GABAergic, inhibiting the neurons of the subthalamic nucleus. Excitatory, glutamatergic inputs come from the cerebral cortex (particularly the motor cortex), and from the pars parafascicularis of the central complex.The subthalamic nucleus also receives neuromodulatory inputs, notably dopaminergic axons from the substantia nigra pars compacta[5]. The globus pallidus (Latin for pale body) is a sub-cortical structure in the brain. ... Location of the cerebral cortex Slice of the cerebral cortex, ca. ... A neuromodulator is a substance other than a neurotransmitter, released by a neuron at a synapse and conveying information to adjacent or distant neurons, either enhancing or damping their activities. ... Dopamine is a chemical naturally produced in the body. ... The substantia nigra (Latin for black substance) is a portion of the midbrain thought to be involved in certain aspects of movement and attention. ...


Efferent targets

The axons of subthalamic nucleus neurons leave the nucleus dorsally. The efferent axons are glutamatergic (excitatory). Except for the connection to the striatum (17.3% in macaques), most of the subthalamic principal neurons are multitargets and directed to the other elements of the core of the basal ganglia[4]. Some send axons to the substantia nigra medially and to the medial and lateral nuclei of the pallidum lateraly (3-target, 21.3%). Some are 2-target with the lateral pallidum and the substantia nigra (2.7%) or the lateral pallidum and the medial (48%). Less are single target for the lateral pallidum. In the pallidum, subthalamic terminals end in bands parallel to the pallidal border[6] and Smith et al.1990). When all axons reaching this target are added, the main afference of the subthalamic nucleus is, in 82.7% of the cases, clearly the lateral pallidum (external segment of the globus pallidus). Coronal slices of human brain showing the basal ganglia, globus pallidus: external segment (GPe), subthalamic nucleus (STN), globus pallidus: internal segment (GPi), and substantia nigra (SN). ...


Some researchers have reported internal axon collaterals[7]. However, there is little functional evidence for this. An axon, or nerve fiber, is a long slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neurons cell body or soma. ...


Physiology

The subthalamic neurons are "fast-spiking pacemakers"[8], spontaneously generating action potentials at rates of 80 to 90Hz in primates (4–40 Hz in rodents). A. A schematic view of an idealized action potential illustrates its various phases as the action potential passes a point on a cell membrane. ...


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"[9] with synchronous bursts. The connection of the lateral pallidum with the subthalamic nucleus is also that in the basal ganglia system where the reduction between emmiter/receiving elements is likely the strongest. In terms of volume, in humans, the lateral pallidum mesures 808mm3, the subthalamic only 158mm3 (Yelnik, 2002). This tanslated in numbers of neurons represents a strong compression with loss of map precision. The systemic position of this circuit is particular in the basal ganglia system. There are two outputs paths starting from the stiatum. The first has a first relay in the medial pallidum (GABAegic inhibitory), sends axons to a particular place of the thalamus, the nucleus ventralis oralis VO (again GaBaergic and inhibitory). VO sends its axons to the accessory motor and the motor cortex (this time with glutamate as the mediator). The second output subsystem follows exactly the same pattern, this time starting from the nigra reticulata (GABA) to the nucleus ventralis anterior VA (GABA again) and from there to the frontal cortex and oculomotor areas (again glutamate). These two output subsystems do not send regulatory messages either to the striatum, lateral pallidum or subthalamic nucleus. The lateropallido-subthalamic subsystem is particular in that it does the reverse. It does not send axons to the thalamus and from there to the cortex. All efferent axons are returning inside the basal ganglia system. Some from the lateral pallidum go to the striatum (Sato et al.2000). The activity of the medial pallidum is influenced by afferences from the lateral pallidum and from the subthalamic nucleus (Smith, Y., Wichmann,T.,DeLong, M.R. 1994).So is that of the nigra reticulata (Smith, Y., Hazrati, L_N, Parent, A. 1990). The subthalamic nucleus sends axons to another regulator the pedunculo-pontine complex (id). This network is thought to play a key role in the generation of the patterns of activity seen in Parkinson's disease[10]. Please wikify (format) this article as suggested in the Guide to layout and the Manual of Style. ...


Physiopathology and interventions

The chronic stimulation of the nucleus leads to a clear improvement of Parkinsonian symptoms. The first to be stimulated are the terminal arborisations of afferent axons which modifies the activity of subthalamic neurons. However trigger zones may also send fastly the signals to the output axons.The effects of stimulation are the objects of many works. Deep brain stimulation (DBS) is one of a group of treatments involving surgical implantation of a medical device called a brain pacemaker, which sends electrical impulses to specific parts of the brain. ...


Pathology

Unilateral destruction or disruption of the subthalamic nucleus – which can commonly occur via a small vessel stroke in patients with diabetes, hypertension, or a history of smoking – produces hemiballismus. Hemiballismus is a movement disorder characterised by unilateral wild, large amplitude flinging movements of the arm and leg, normally causing falls and preventing postural maintenance. ...


References

  1. ^ Luys, Jules Bernard (1865). Recherches sur le système cérébro-spinal, sa structure, ses fonctions et ses maladies (in French). Paris: Baillière.
  2. ^ Yelnik, J. & Percheron, G. (1979). "Subthalamic neurons in primates : a quantitative and comparative anatomy". Neuroscience 4 (11): 1717–1743. PMID 117397.
  3. ^ Levesque J.C. & Parent A. (2005). "GABAergic interneurons in human subthalamic nucleus". Movement Disorders 20 (5): 574–584. PMID 15645534.
  4. ^ a b Sato F.; Parent M.; Levesque M.; & Parent A. (2000). "Axonal branching pattern of neurons of the subthalamic nucleus in primates". Journal of Comparative Neurology 424 (1): 142–152. PMID 10888744.
  5. ^ Cragg S.J.; Baufreton J.; Xue Y.; Bolam J.P.; & Bevan M.D. (2004). "Synaptic release of dopamine in the subthalamic nucleus". European Journal of Neuroscience 20 (7): 1788–1802. PMID 15380000.
  6. ^ Nauta, H.J.W. & Cole, M. (1978). "Efferent projections of the subthalamic nucleus : an autoradiographic study in monkey and cat". Journal of Comparative Neurology 180 (1): 1–16. PMID 418083.
  7. ^ Kita, H.; Chang, H.T.; & Kitai, S.T. (1983). "The morphology of intracellularly labeled rat subthalamic neurons: A light microscopic analysis". Neuroscience 215 (3): 245–257. PMID 6304154.
  8. ^ Surmeier D.J.; Mercer J.N.; & Chan C.S. (2005). "Autonomous pacemakers in the basal ganglia: who needs excitatory synapses anyway?". Current Opinion in Neurobiology 15 (3): 312–318. PMID 15916893.
  9. ^ Plenz, D. & Kitai, S.T. (1999). "A basal ganglia pacemaker formed by the subthalamic nucleus and external globus pallidus". Nature 400 (6745): 677–682. PMID 10458164.
  10. ^ Bevan M.D.; Magill P.J.; Terman D.; Bolam J.P.; & Wilson CJ. (2002). "Move to the rhythm: oscillations in the subthalamic nucleus-external globus pallidus network". Trends in Neurosciences 25 (10): 525–531. PMID 12220881.
  • Sato, F., Lavallée, P., Levesque, M. and Parent, A. (2000) Single-axon tracing study of neurons of the external segment of the globus pallidus in primate. J. Comp. Neurol. 417: 17-31
  • Smith, Y., Hazrati, L-N. and Parent, A. (1990) Efferent projections of the subthalamic nucleus in the squirrel monkey as studied by the PHA-L anterograde tracing method. J. Comp. Neurol. 294: 306-323
  • Smith, Y., Wichmann, T. and DeLong, M.R. (1994) Synaptic innervation of neurones in the internal pallidal segment by the subthalamic nucleus and the external pallidum in monkeys. J. Comp. Neurol. 343: 297-318
  • Yelnik, J. (2002) Functional anatomy of the basal ganglia. Mov. Disord.17:S15-S21

Jules Bernard Luys (1828–1897) was a French neurologist who made important contributions to the fields of neuroanatomy and neuropsychiatry. ...

External links

  • MeSH A08.186.211.730.385.800.800

Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. ...

see also

[[Primate basal ganglia ]]


  Results from FactBites:
 
Subthalamic nucleus - Wikipedia, the free encyclopedia (566 words)
The subthalamic nucleus (or nucleus subthalamicus) first described by Luys (1865, the term Luys' body-corpus Luysi- is still sometimes used) is a relatively small lens-shaped nucleus belonging to the basal ganglia system (see primate basal ganglia system).
The subthalamic nucleus receives its main afference from the lateral pallidum througth the ansa lenticularis.It also receives dopaminergic (containing dopamine) axons from the substantia nigra, neuromodulatory, and other afferences from the pars parafascicularis of the central complex that are glutamatergic (excitatory).
When all axons reaching this target are added, the main afference of the subthalamic nucleus is, in 82,7% of the cases, clearly the lateral pallidum (external segment of the globus pallidus).
Neurological Exam: Cerebellum: Lesions: Vascular Lesions - Hemorrhage in the Subthalamic Nucleus (375 words)
Preservation of speech, involvement of both the arm and leg and normal cranial nerve functions suggests a lesion at the level of the posterior limb of the internal capsule rather that at the cortex.
The involuntary, sudden and violent swinging of the extremities, which disappears in sleep, on the right side is "ballism" and is associated with lesions of the left subthalamic nucleus.
The blood supply to the subthalamic nucleus and the adjacent posterior limb of the internal capsule is by branches of the posterior communicating artery of the circle of Willis.
  More results at FactBites »


 

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