Brain: Basal ganglia
Basal ganglia labeled at top right.
Latin	nuclei basales
NeuroNames	hier-206
MeSH	Basal+Ganglia
Dorlands/Elsevier	n_11/12580456

The basal ganglia (or basal nuclei) are a group of nuclei in the brain interconnected with the cerebral cortex, thalamus and brainstem. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. 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 In Neuroanatomy, a nucleus is a Central nervous system structure that is composed mainly of Gray matter, and that acts as a hub or transit point for The brain is the center of the Nervous system in animals All Vertebrates and the majority of Invertebrates have a brain The cerebral cortex is a structure within the Brain that plays a key role in Memory, Attention, perceptual Awareness, Thought, The thalamus (from Greek θάλαμος = room chamber, IPA= /ˈθæləməs/ is a pair and symmetric part of the brain The brain stem (or brainstem) is the lower part of the Brain, adjoining and structurally continuous with the Spinal cord. Mammalian basal ganglia are associated with a variety of functions: motor control, cognition, emotions, and learning. Mammals ( class Mammalia) are a class of Vertebrate Animals characterized by the presence of Sweat glands, including sweat glands In the fields of Neuropsychology, Personal development and Education, Learning is one of the most important Mental function of humans

History

The acceptance that the basal ganglia system constitutes one major cerebral system has been slow to appear.

The first anatomical identification of distinct subcortical structures was published by Thomas Willis in 1664. Anatomy (from the Greek anatomia, from ana separate apart from and temnein, to cut up cut open is a branch of Biology that is the consideration Thomas Willis ( 27 January 1621 &ndash 11 November 1675) was an English doctor who played an important part in the history of ^[1] For many years, the term corpus striatum was used to describe a large group of subcortical elements, some of which were later discovered to be functionally unrelated. The striatum is a subcortical (ie inside rather than on the outside part of the Telencephalon. Additionally, the putamen and the caudate nucleus were not linked together. "Putamen" is also a botanical term for the stone in a Fruit, such as a Peach. The caudate nucleus is a nucleus located within the Basal ganglia of the Brains of many animal species The putamen was thought to be associated to the pallidum in what used to be called the "nucleus lenticularis" (see lentiform nucleus on the fig. The globus pallidus ( Latin for "pale globe" is a sub- cortical structure of the Brain. The lentiform nucleus or lenticular nucleus comprises the Putamen and the Globus pallidus within the Basal ganglia. ).

Pioneering work by Cécile and Oskar Vogt (1941) greatly simplified the description of the basal ganglia by proposing the term striatum to describe the group of structures consisting of the caudate nucleus, the putamen and the mass linking them ventrally, the nucleus accumbens. The striatum is a subcortical (ie inside rather than on the outside part of the Telencephalon. In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species The nucleus accumbens (NAcc also known as the accumbens nucleus or as the nucleus accumbens septi (Latin for nucleus leaning against the Septum

The striatum gets its name from the striated appearance created by radiating dense bundles of striato-pallido-nigral axons, described by anatomist Kinnear Wilson as "pencil-like". An axon or nerve fiber is a long slender projectionof a nerve cell or Neuron, that conducts electrical impulses away from the neuron's Cell The anatomical link of the striatum with its primary targets, the pallidum and the substantia nigra was later discovered. The globus pallidus ( Latin for "pale globe" is a sub- cortical structure of the Brain. The substantia nigra ( Latin for "black substance" Sömmering) or locus niger is a heterogeneous portion of the midbrain, separating Together, these structures constitute the striato-pallido-nigral bundle, which is the core of the basal ganglia. This nerve bundle forms the so-called "comb bundle of Edinger" when it crosses the internal capsule. The internal capsule is an area of White matter in the Brain that separates the Caudate nucleus and the Thalamus from the Lenticular nucleus

Additional structures that later became associated with the basal ganglia are the "body of Luys" (1865) (nucleus of Luys on the figure) or subthalamic nucleus, whose lesion was known to produce movement disorders. The subthalamic nucleus is a small lens-shaped nucleus in the Brain where it is a part of the Basal ganglia system More recently, other areas such as the central complex (centre médian-parafascicular) and the pedunculopontine complex have been thought to be regulators of the basal ganglia. The pedunculopontine nucleus ( PPN) (or pedunculopontine tegmental nucleus, PPTN) is located in the Brainstem, caudal to the Substantia nigra

At the beginning of the 20th century, the basal ganglia system was associated with motor functions, as lesions of these areas would often result in disordered movement in humans (chorea, athetosis, Parkinson's disease). Athetosis is a continuous stream of slow sinuous writhing movements typically of the Hands and feet. Parkinson's disease (also known as Parkinson disease or PD) is a degenerative disorder of the Central nervous system that often impairs the sufferer's

Anatomical subdivisions

Coronal slices of human brain showing the basal ganglia. In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species
ROSTRAL: striatum, globus pallidus (GPe and GPi)
CAUDAL: subthalamic nucleus (STN), substantia nigra (SN)

Main article: Anatomical subdivisions and connections of the basal ganglia

The five individual nuclei that make up the primate basal ganglia, along with their major subdivisions, are:

rostral

• the striatum, which consists of
  • putamen
  • caudate nucleus
  • nucleus accumbens
• external segment of the globus pallidus (GPe)
• internal segment of the globus pallidus (GPi)

caudal

• subthalamic nucleus (STN)
• substantia nigra (SN)
  • substantia nigra pars compacta (SNc)
  • substantia nigra pars reticulata (SNr)
  • substantia nigra pars lateralis (SNl)

There are 2 sets of basal ganglia in the mammalian brain, mirrored in the left and right hemispheres. The striatum is a subcortical (ie inside rather than on the outside part of the Telencephalon. The globus pallidus ( Latin for "pale globe" is a sub- cortical structure of the Brain. The subthalamic nucleus is a small lens-shaped nucleus in the Brain where it is a part of the Basal ganglia system The substantia nigra ( Latin for "black substance" Sömmering) or locus niger is a heterogeneous portion of the midbrain, separating The primate basal ganglia system is a symmetrical major cerebral system that has only recently been recognized A primate is a member of the biological order Primates ( Latin: "prime first rank" the group that contains Lemurs the Aye-aye The striatum is a subcortical (ie inside rather than on the outside part of the Telencephalon. "Putamen" is also a botanical term for the stone in a Fruit, such as a Peach. The caudate nucleus is a nucleus located within the Basal ganglia of the Brains of many animal species The nucleus accumbens (NAcc also known as the accumbens nucleus or as the nucleus accumbens septi (Latin for nucleus leaning against the Septum The globus pallidus ( Latin for "pale globe" is a sub- cortical structure of the Brain. In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species The subthalamic nucleus is a small lens-shaped nucleus in the Brain where it is a part of the Basal ganglia system The substantia nigra ( Latin for "black substance" Sömmering) or locus niger is a heterogeneous portion of the midbrain, separating

Two coronal sections are used to show the basal ganglia; the STN and substantia nigra lie deeper back in the brain (more caudal). In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species Images show two schematic coronal cross-sections of the human brain with nuclei of the basal ganglia labeled on the right side. In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species Human beings, humans or man (Origin 1590–1600 L homō man OL hemō the earthly one (see Humus

Functionally, the basal ganglia consist of a series of circuits, such as skeletomotor, limbic and occulomotor circuits. Each circuit projects to specific nuclei within the basal ganglia and its projections e. g. the skeletomotor circuit projects to the ventral lateral, lateral ventral anterior and centromedian thalamic nuclei.

Comparative anatomy and naming

"Basal ganglia"-like areas are found in the central nervous systems of many species. The striatal and pallidal components can be clearly identified in all amniotes (mammals, birds, and reptiles) and amphibians. The amniotes are a group of Tetrapod Vertebrates that include the Synapsida ( Mammals and Mammal-like reptiles and Sauropsida Prehistoric amphibian Amphibians (class Amphibia such as Frogs Toads Salamanders Newts Gymnophiona, Sirens and The anatomical connections of these nuclei and their pharmacology also appear relatively conserved. Pharmacology (from Greek grc φάρμακον pharmakon, "drug" and grc -λογία -logia) is the study of how Drugs Non-tetrapod vertebrates such as fish also display basal ganglia-like structures, although the data are less clear in this case. Tetrapods ( Greek τετραποδη tetrapoda, Latin Quadruped, "four-footed" are Vertebrate Animals

The names given to the various nuclei of the basal ganglia are different in different species:

• For example, the "internal segment of the globus pallidus" in primates is called the "entopenduncular nucleus" in rodents. Rodentia is an order of Mammals also known as rodents, characterised by two continuously-growing incisors in the upper and lower jaws which must
• The "striatum" and "external segment of the globus pallidus" in primates are called the "paleostriatum augmentatum" and "paleostriatum primitivum" respectively in birds.

A clear emergent issue in comparative anatomy of the basal ganglia is the development of this system through phylogeny as a convergent cortically re-entrant loop in conjunction with the development and expansion of the cortical mantle. There is controversy, however, regarding the extent to which convergent selective processing occurs versus segregated parallel processing within re-entrant closed loops of the basal ganglia. Regardless, the transformation of the basal ganglia into a cortically re-entrant system in mammalian evolution occurs through a re-direction of pallidal (or "paleostriatum primitivum") output from midbrain targets such as the superior colliculus, as occurs in sauropsid brain, to specific regions of the ventral thalamus and from there back to specified regions of the cerebral cortex that form a subset of those cortical regions projecting into the striatum. Reptiles, or members of the class Reptilia are air-breathing Cold-blooded Vertebrates that have skin covered in scales as opposed to hair or feathers The abrupt rostral re-direction of the pathway from the internal segment of the globus pallidus into the ventral thalamus--via the path of the ansa lenticularis--could be viewed as a footprint of this evolutionary transformation of basal ganglia outflow and targeted influence. The ansa lenticularis ( ansa lentiformis in older texts is a part of the brain making up the superior layer of the substantia innominata of Meynert. The evolutionary emergence of cortical re-entrant systems in the brain has been postulated by Gerald Edelman as a critical basis for the emergence of primary consciousness in the theory of Neural Darwinism. Gerald Maurice Edelman (born July 1, 1929) is an American biologist who won the 1972 Nobel Prize in Physiology or Medicine for his Consciousness has been defined loosely as a constellation of attributes of Mind such as Subjectivity, Self-awareness, Sentience, and the Neural Darwinism, a large scale theory of brain function by Gerald Edelman, was initially published in 1978 in a book called The Mindful Brain (MIT Press

Connections

Connectivity Diagram showing glutamatergic pathways as red, dopaminergic as magenta and GABA pathways as blue. Glutamic acid (abbreviated as Glu or E) is one of the 20 Alpha Amino acids It is not among the human Essential amino acids Its Dopaminergic means "related to the Neurotransmitter Dopamine " Gamma-aminobutyric acid (GABA is the chief inhibitory Neurotransmitter in the Mammalian Central nervous system.

Basal ganglia connectivity is illustrated in the figure.

The striatum is the main (but not the only) input zone for other brain areas to connect to the basal ganglia. Via the striatum, the basal ganglia receives input from the cortex, mainly from the motor and prefrontal cortices. The cerebral cortex is a structure within the Brain that plays a key role in Memory, Attention, perceptual Awareness, Thought, Motor cortex is a term that describes regions of the Cerebral cortex involved in the planning control and execution of voluntary motor functions

The circuitry of the basal ganglia is often divided into two major pathways, the direct pathway and the indirect pathway:

Dopamine from the substantia nigra pars compacta stimulates all of the dopamine receptors, but because the different pathways express different receptors, and the different receptors have different effects, dopamine serves to activate the direct pathway over the indirect pathway, and thus increase the signal to the thalamus. Dopamine is a Hormone and Neurotransmitter occurring in a wide variety of animals including both vertebrates and invertebrates The substantia nigra ( Latin for "black substance" Sömmering) or locus niger is a heterogeneous portion of the midbrain, separating Dopamine receptors are a class of metabotropic G protein-coupled receptors that are prominent in the Vertebrate Central nervous system (CNS

Neurotransmitters

The different types of neuron of the basal ganglia biosynthesize different neurotransmitters. See Chemical synapse for an introduction to concepts and terminology used in this article

Other disorders linked with the basal ganglia

• Attention-deficit hyperactivity disorder (ADHD)
• Athymhormic syndrome (PAP syndrome)
• Cerebral palsy: basal ganglia damage during second and third trimester of pregnancy
• Dystonia
• Fahr's disease
• Foreign accent syndrome (FAS)
• Huntington's disease
• Lesch-Nyhan syndrome
• Obsessive-compulsive disorder
• Parkinson's disease
• Tourette's disorder
• Tardive dyskinesia, caused by chronic antipsychotic treatment
• Stuttering^[2]
• Spasmodic dysphonia
• Wilson's disease

Terminology

As it refers to a group of nuclei, the term "basal ganglia" is plural (the singular of ganglia is ganglion). Attention-Deficit Hyperactivity Disorder (ADHD is a neurobehavioral developmental disorder affecting about 3-5% of the world's population Athymhormic syndrome, or psychic akinesia, is a rare neurological Syndrome characterized by extreme passivity apathy and a profound generalized loss of Athymhormic syndrome, or psychic akinesia, is a rare neurological Syndrome characterized by extreme passivity apathy and a profound generalized loss of Cerebral palsy ( CP) is an Umbrella term encompassing a group of non-progressive, non- contagious conditions that cause Physical disability Dystonia is a neurological Movement disorder in which sustained muscle contractions cause twisting and repetitive movements or abnormal postures Idiopathic Basal Ganglia Calcification, also known as Fahr disease or Fahr’s Syndrome is a rare genetically dominant, inherited neurological Foreign accent syndrome is a rare Medical condition that usually occurs as a rare side effect of severe Brain injury such as a Stroke or a head injury Huntington's disease, also called Huntington's chorea, chorea major, or HD, is a genetic neurological disorder characterized after Lesch-Nyhan syndrome ( LNS) also known as Nyhan’s syndrome or Kelley-Seegmiller syndrome, is a rare Inherited disorder caused by a deficiency Obsessive-compulsive disorder (OCD is a Chronic Anxiety disorder most commonly characterized by obsessive Distressing Intrusive thoughts Parkinson's disease (also known as Parkinson disease or PD) is a degenerative disorder of the Central nervous system that often impairs the sufferer's Tourette syndrome (also called Tourette's syndrome, Tourette's disorder, Gilles de la Tourette syndrome, GTS or more commonly simply Tourette's Tardive dyskinesia is a variety of dyskinesia (involuntary repetitive movements manifesting as a side effect of long-term or high-dose use of Dopamine antagonists Antipsychotics are a group of Psychoactive drugs commonly but not exclusively used to treat Psychosis, which is typified by Schizophrenia. Spasmodic dysphonia (or laryngeal dystonia is a Voice disorder characterized by involuntary movements of one or more Muscles of the Larynx (vocal folds Wilson's disease or hepatolenticular degeneration is an Autosomal recessive Genetic disorder in which Copper accumulates in tissues In Anatomy, a ganglion (pl ganglia) is a tissue mass. Neurology In neurological contexts ganglia are composed mainly of However this is a misnomer, as "ganglion" refers to a somatic cluster within the peripheral nervous system, whereas the basal ganglia are within the central nervous system (CNS). A misnomer is a term which suggests an interpretation that is known to be untrue The soma, or cyton or perikaryon, is the bulbous end of a Neuron, containing the Cell nucleus. The peripheral nervous system ( PNS) resides or extends outside the Central nervous system (CNS which consists of the Brain and Spinal cord. In Vertebrates the central nervous system ( CNS) is the part of the Nervous system which is enclosed in the Meninges. A somatic cluster within the CNS is referred to as a nucleus, so some neuroanatomists refer to the basal ganglia as the "basal nuclei". Neuroanatomy is the science for localizing function in the Human brain. ^[3]

See also

• Anatomical subdivisions and connections of the basal ganglia
• Nathaniel A. Buchwald
• Primate basal ganglia system

References

1. ^ Andrew Gilies, A brief history of the basal ganglia, retrieved on 27 June 2005
2. ^ Alm PA (2004). The primate basal ganglia system is a symmetrical major cerebral system that has only recently been recognized Nathaniel A Buchwald ( July 19, 1924 - July 14 2006) was an American Neuroscientist, educator and administrator who was Professor The primate basal ganglia system is a symmetrical major cerebral system that has only recently been recognized Events 1358 - Republic of Dubrovnik is founded 1709 - Peter the Great defeats Charles XII of Sweden Year 2005 ( MMV) was a Common year starting on Saturday (link displays full calendar of the Gregorian calendar. "Stuttering and the basal ganglia circuits: a critical review of possible relations". Journal of communication disorders 37 (4): 325-69. doi:10.1016/j.jcomdis.2004.03.001. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document. PMID 15159193.  
3. ^ Soltanzadeh, Akbar (2004). Neurologic Disorers. Tehran: Jafari. ISBN ISBN 964-6088-03-1.  

• Nolte, John, The Human Brain: An Introduction to its Functional Anatomy (Fifth Edition). (St. Louis: Mosby, Inc. , 2002), 464-484. ISBN 0-323-01320-1
• Parent, André, Comparative Neurobiology of the Basal Ganglia (Wiley, New York, 1986), ISBN 0-471-80348-0
• Reynolds JN, Hyland BI, Wickens JR (2001). "A cellular mechanism of reward-related learning". Nature 413 (6851): 67-70. Nature is a prominent Scientific journal, first published on 4 November 1869 PMID 11544526.  

Additional images

Basal ganglia

The major components of the basal ganglia are the caudate nucleus, putamen, and globus pallidus

Schematic representation of the chief ganglionic categories (I to V).

External links

• Basal+ganglia at eMedicine Dictionary
• Imaging of Basal Ganglia at USUHS