Brain: Globus pallidus
Globus pallidus labeled at bottom right.
DA-loops in PD
NeuroNames	hier-213
MeSH	Globus+Pallidus
Dorlands/Elsevier	g_07/12394364

The globus pallidus (Latin for "pale globe") is a sub-cortical structure of the brain. NeuroNames is a system of nomenclature for the human and/or macaque Brain. Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and books Elsevier, the world's largest Publisher of Medical and Scientific literature, forms part of the Reed Elsevier group Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. The cerebral cortex is a structure within the Brain that plays a key role in Memory, Attention, perceptual Awareness, Thought, The brain is the center of the Nervous system in animals All Vertebrates and the majority of Invertebrates have a brain It is a major element of the basal ganglia system. The basal ganglia (or basal nuclei) are a group of nuclei in the Brain interconnected with the Cerebral cortex, Thalamus and In this system, it is a major constituent of the basal ganglia core, which consists of the striatum and its direct targets: globus pallidus and substantia nigra. The substantia nigra ( Latin for "black substance" Sömmering) or locus niger is a heterogeneous portion of the midbrain, separating The last two are made up of the same neuronal elements, have a similar main afferent (the dorsal striatum), have a similar synaptology, and do not receive cortical afferents. The striatum is a subcortical (ie inside rather than on the outside part of the Telencephalon. Chemical synapses are specialized junctions through which Neurons signal to each other and to non-neuronal cells such as those in Muscles or Glands

History of name

The origin of the name is not established. It was known by Dejerine (1906) but not by Santiago Ramón y Cajal (1909-1911). Santiago Ramón y Cajal ( May 1 1852 &ndash October 17 1934) was a Spanish histologist, Physician, and As the elements in no way have the shape of a globe, Foix and Nicolesco (1925), the Vogts (1941), Crosby et all. (1962) followed by the Terminologia anatomica proposed the simpler term (neutral adjective) of pallidum (pale). During a long period the globus pallidus was unduly linked to the putamen in the lentiform nucleus (nucleus lenticularis or lentiformis). The lentiform nucleus or lenticular nucleus comprises the Putamen and the Globus pallidus within the Basal ganglia. This was a heterogeneous anatomical entity that is part of the striatum rather than the pallidum. The striatum is a subcortical (ie inside rather than on the outside part of the Telencephalon. The link with the substantia reticulata was stressed very early on due to the similarities in dendritic arborisation, but in spite of solid arguments this link is still not widely accepted. The two however constitute a particular set of the basal ganglia system (the pallidonigral set).

Parts

In primates, the dorsal pallidum, or globus pallidus, is divided into two segments by the medial medullary lamina. A primate is a member of the biological order Primates ( Latin: "prime first rank" the group that contains Lemurs the Aye-aye A frequent nomenclature uses the adjectives internal and external to refer to the two divisions of the globus pallidus. The medial segment of the dorsal pallidum, internal globus pallidus (GPi), and lateral division of the dorsal pallidum, external globus pallidus (GPe), are thus the two parts of the dorsal pallidum that are two closed nuclei surrounded everywhere by myelinic walls.

The ventral pallidum lies within the substantia innominata (Latin for un-named substance) and receives efferent connections from the ventral striatum (nucleus accumbens and olfactory tubercle). The striatum is a subcortical (ie inside rather than on the outside part of the Telencephalon. The nucleus accumbens (NAcc also known as the accumbens nucleus or as the nucleus accumbens septi (Latin for nucleus leaning against the Septum Olfaction (also known as olfactics or smell) refers to the Sense of smell. The ventral pallidum projects to the dorsomedial nucleus of the dorsal thalamus, which projects to the prefrontal cortex. The thalamus (from Greek θάλαμος = room chamber, IPA= /ˈθæləməs/ is a pair and symmetric part of the brain The ventral pallidum also projects to the pedunclopontine nucleus and tegmental motor area. The function of the ventral pallidum is limbic-somatic motor interface for the planning and inhibition of movements from the dorsal striatopallidal complex.

Structure

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. Parvalbumin is a Calcium binding albumin protein It has three EF hand motifs and is structurally related to Calmodulin and Troponin These have the peculiarity of having the three-dimensional shape of flat discs, parallel to one another, parallel to the border of the pallidum^[1] and perpendicular to the afferent striatopallidal axons. ^[2] There are only a few small local circuitry neurons.

The globus pallidus is traversed by the numerous myelinated axons of the striato-pallidonigral bundle that give it the pale appearance from which it is named. Myelin is an electrically-insulating Dielectric Phospholipid layer that surrounds only the Axons of many Neurons It is an outgrowth

The ultrastructure is very peculiar, as the long dendrites are everywhere, without discontinuity, covered by synapses. ^[3][4]

Pallidonigral pacemaker

The two pallidal nuclei and the two nigral (pars compacta and pars reticulata) parts constitute a high-frequency autonomous pacemaker^[5] (see primate basal ganglia system)

Common afferences

The two parts receive successively a large quantity of GABAergic axonal terminal arborisations from the striatum through the dense striato-pallidonigral bundle. The primate basal ganglia system is a symmetrical major cerebral system that has only recently been recognized The striatum is a subcortical (ie inside rather than on the outside part of the Telencephalon. The synaptology is very peculiar (see primate basal ganglia system). The primate basal ganglia system is a symmetrical major cerebral system that has only recently been recognized ^[3][4]The striatal afference contribute for more than 90% of synapses. The two pallidal nuclei receives dopaminergic axons from the pars compacta of the substantia nigra.

Coronal slices of human brain showing the basal ganglia.
ROSTRAL: striatum, globus pallidus (GPe and GPi)
CAUDAL: subthalamic nucleus (STN), substantia nigra (SN)

See also

• Lentiform nucleus

References

Additional images

Coronal section of brain through intermediate mass of third ventricle.

Coronal section of brain through anterior commissure.

Horizontal section of right cerebral hemisphere.

Connectivity Diagram showing glutamatergic pathways as red, dopaminergic as magenta and GABA pathways as blue.

External links

• BrainMaps at UCDavis Globus pallidus

• Globus+pallidus at eMedicine Dictionary
• Paleostriatum at eMedicine Dictionary
• Diagram at uni-tuebingen.de