Theglobus pallidus(GP), also known aspaleostriatumordorsal pallidum,[1]is a major component of thesubcorticalbasal gangliain thebrain.It consists of two adjacent segments, oneexternal(or lateral), known in rodents simply as theglobus pallidus,and oneinternal(or medial), known in rodents as theentopeduncular nucleus.It is part of thetelencephalon,but retains close functional ties with thesubthalamusin thediencephalon– both of which are part of theextrapyramidal motor system.[2]
| Globus pallidus | |
|---|---|
 Globus pallidus (in red) shown within the brain | |
 Dopamine-loops in Parkinson's disease | |
| Details | |
| Part of | Basal ganglia |
| Identifiers | |
| Latin | globus pallidus |
| Acronym(s) | GP |
| MeSH | D005917 |
| NeuroNames | 231 |
| NeuroLexID | birnlex_1234 |
| TA98 | A14.1.09.518 |
| TA2 | 5569 |
| FMA | 61835 |
| Anatomical terms of neuroanatomy | |
The globus pallidus receives principal inputs from thestriatum,and principal direct outputs to thethalamusand thesubstantia nigra.The latter is made up of similar neuronal elements, has similar afferents from the striatum, similar projections to the thalamus, and has a similarsynaptology.Neither receives direct cortical afferents, and both receive substantial additional inputs from theintralaminar thalamic nuclei.
Globus pallidus isLatinfor "pale globe".
Structure
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Pallidal nuclei are made up of the same neuronal components. In primates, almost all pallidal neurons are very large,parvalbumin-positive, with very large dendritic arborizations. These have the peculiarity of having the three-dimensional shape of flat discs, parallel to one another, parallel to the border of the pallidum[3]and perpendicular to the afferentstriatopallidalaxons.[4]There are only a few small local circuitry neurons.
The globus pallidus is traversed by the numerousmyelinatedaxons of thestriatopallidonigral bundlethat give it the pale appearance from which it is named.
The ultrastructure is very peculiar, as the long dendrites are everywhere, without discontinuity, covered by synapses.[5][6]
Parts
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In primates, the globus pallidus is divided into two parts by a thinmedial medullary lamina.[7]These are theinternal globus pallidus(GPi) and theexternal globus pallidus(GPe); both are composed of closed nuclei surrounded by myelinic walls.
Theventral pallidumlies within thesubstantia innominata(Latin for unnamed substance) and receives efferent connections from the ventralstriatum(thenucleus accumbensand theolfactory tubercle). It projects to the dorsomedial nucleus of the dorsalthalamus,which, in turn, projects to theprefrontal cortex;it also projects to thepedunculopontine nucleusandtegmentalmotor areas. Its function is to serve as a limbic-somatic motor interface, and it is involved in the planning and inhibition of movements from the dorsal striatopallidal complex.
Function
editThe globus pallidus is a structure in the brain involved in the regulation of voluntary movement.[8]It is part of thebasal ganglia,which, amongmany other functions,regulate movements that occur on the subconscious level. Damage to the globus pallidus can causemovement disorders,as its regulatory function will be impaired. There may be cases in which damage is deliberately induced, as in a procedure known as apallidotomy,[9]in which a lesion is created to reduce involuntary muscle tremors. When it comes to regulation of movement, the globus pallidus has a primarily inhibitory action that balances the excitatory action of the cerebellum. These two systems evolved to work in harmony with each other to allow smooth and controlled movements. Imbalances can result in tremors, jerks, and other movement problems, as seen in some people with progressive neurological disorders characterized by symptoms like tremors.
The basal ganglia act on a subconscious level, requiring no conscious effort to function. When someone makes a decision to engage in an activity such as petting a dog, for example, these structures help to regulate the movement to make it as smooth as possible, and to respond to sensory feedback. Likewise, the globus pallidus is involved in the constant subtle regulation of movement that allows people to walk and engage in a wide variety of other activities with a minimal level of disruption.[citation needed]
Pallidonigral pacemaker
editThe two pallidal nuclei and the two parts of the substantia nigra (thepars compactaandpars reticulata) constitute a high-frequency autonomous pacemaker.[10](seeprimate basal ganglia#Pallidonigral set and pacemaker)
Common afferents
editThe two parts receive successively a large quantity ofGABAergicaxonal terminal arborisations from thestriatumthrough the dense striato-pallidonigral bundle. The synaptology is very peculiar (seeprimate basal ganglia system).[5][6]The striatal afferents contribute more than 90% of synapses.[citation needed] The two pallidal nuclei receive dopaminergic axons from the pars compacta of the substantia nigra.
ROSTRAL:striatum,globus pallidus (GPe and GPi)
CAUDAL:subthalamic nucleus(STN),substantia nigra(SN)
Pathway
editThis area of the basal ganglia receives input from another area, called the striatum, which has two parts, thecaudate nucleusand theputamen.This data is routed to the thalamus, either directly or indirectly. In the case of the interna, one area of the globus pallidus, the structure can feed directly to the thalamus. The externa, which lies on the outside of this structure, feeds information to the interna, where it can be passed on to the thalamus.
History
editThe origin of the name is not established. It was used byJoseph Dejerine(1906) but not bySantiago Ramón y Cajal(1909–1911).
As the elements in no way have the shape of a globe, throughout the 20th century scientists proposed a simpler term (a neuter adjective),pallidum(meaning "pale" ). Propositions include those by Foix and Nicolesco (1925), the Vogts (1941), Crosby et al. (1962) and theTerminologia Anatomica.
For a long time the globus pallidus was linked to the putamen and termed thelentiform nucleus(nucleus lenticularis or lentiformis), a heterogeneous anatomical entity that is part of thestriatumrather than the pallidum. The link with thesubstantia nigrapars reticulata was stressed very early on due to the similarities in dendritic arborisation (and they are sometimes known as the pallidonigral set) but, in spite of strong evidence, this association remains controversial.
See also
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edit- ^Reiner, Anton; Perkel, David J.; Bruce, Laura L.; Butler, Ann B.; Csillag, András; Kuenzel, Wayne; Medina, Loreta; Paxinos, George; Shimizu, Toru; Striedter, Georg; Wild, Martin; Ball, Gregory F.; Durand, Sarah; Gütürkün, Onur; Lee, Diane W.; Mello, Claudio V.; Powers, Alice; White, Stephanie A.; Hough, Gerald; Kubikova, Lubica; Smulders, Tom V.; Wada, Kazuhiro; Dugas-Ford, Jennifer; Husband, Scott; Yamamoto, Keiko; Yu, Jing; Siang, Connie; Jarvis, Erich D. (2004)."Revised Nomenclature for Avian Telencephalon and Some Related Brainstem Nuclei".The Journal of Comparative Neurology.473(3): 377–414.doi:10.1002/cne.20118.PMC2518311.PMID15116397.
- ^Schünke, Michael; Ross, Lawrence M.; Schulte, Erik; Lamperti, Edward D.; Schumacher, Udo (2007).Theme atlas of anatomy: head and neuroanathomy.Thieme.ISBN9781588904416.
- ^Yelnik, J., Percheron, G., and François, C. (1984) A Golgi analysis of the primate globus pallidus. II- Quantitative morphology and spatial orientation of dendritic arborisations. J. Comp. Neurol. 227:200–213
- ^Percheron, G., Yelnik, J. and François. C. (1984) A Golgi analysis of the primate globus pallidus. III-Spatial organization of the striato-pallidal complex. J. Comp. Neurol. 227: 214–227
- ^abFox, C.A., Andrade, A.N. Du Qui, I.J., Rafols, J.A. (1974) The primate globus pallidus. A Golgi and electron microscopic study. J. Hirnforsch. 15: 75–93
- ^abdi Figlia, M., Pasik, P., Pasik, T. (1982) A Golgi and ultrastructural study of the monkey globus pallidus. J. Comp. Neurol. 212: 53–75
- ^Ide, S; Kakeda, S; Yoneda, T; et al. (10 October 2017)."Internal Structures of the Globus Pallidus in Patients with Parkinson's Disease: Evaluation with Phase Difference-enhanced Imaging".Magnetic Resonance in Medical Sciences.16(4): 304–310.doi:10.2463/mrms.mp.2015-0091.PMC5743521.PMID28003623.
- ^Gillies, M. J., Hyam, J. A., Weiss, A. R., Antoniades, C. A., Bogacz, R., Fitzgerald, J. J.,… Green, A. L. (2017). The Cognitive Role of the Globus Pallidus interna; Insights from Disease States. Experimental Brain Research, 235(5), 1455–1465.https://doi.org/10.1007/s00221-017-4905-8>
- ^McCartney, L. K., Bau K., Stewart K., Botha B., Morrow A., (2016), Pallidotomy as a treatment option for a complex patient with severe dystonia , Dev. Med. Child Neurol. 2016 58: (68–69)http://onlinelibrary.wiley.com/doi/10.1111/dmcn.13070/epdf
- ^Surmeier, D.J.,Mercer, J.N. and Savio Chan, C. (2005) Autonomous pacemakers in the basal ganglia: who needs excitatory synapses anyway? Cur. Opin.Neurobiol. 15:312–318.
External links
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