FACTOID # 12: It's not the government they hate: Washington DC has the highest number of hate crimes per capita in the US.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
   
 
WHAT'S NEW
RELATED ARTICLES
People who viewed "Striatum" also viewed:
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


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

The striatum is a subcortical part of the telencephalon. It is the major input station of the basal ganglia system. Image File history File links Basal-ganglia-coronal-sections-large. ... Image File history File links Basal-ganglia-coronal-sections-large. ... The basal ganglia are a group of nuclei in the brain interconnected with the cerebral cortex, thalamus and brainstem. ... The globus pallidus (Latin for pale body) is a sub-cortical structure in the brain. ... 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 globus pallidus (Latin for pale body) is a sub-cortical structure in the brain. ... The substantia nigra, (Latin for black substance, Soemering) or locus niger is a heterogeneous portion of the midbrain, separating the pes (foot) from the tegmentum (covering), and a major element of the basal ganglia system. ... The telencephalon (te-len-seff-a-lon) is the technical name for a large region within the brain which is attributed many functions, which some groups would class as unique features which make humans stand out from other species. ... The basal ganglia are a group of nuclei in the brain associated with motor and learning functions. ...

Contents

History

In the seventeenth and eighteenth centuries, the term "corpus striatum" was used to designate many distinct, deep, infracortical elements of the hemisphere (i.e. Vieussens, 1685). The Vogts (Cécile and Oskar, 1941) simplified the nomenclature by proposing the term striatum for all elements built with striatal elements (see Primate basal ganglia system): the caudate, the putamen and the fundus striati, that ventral part linking the two precedings together ventrally to the inferior part of the internal capsule. The corpus striatum is composed of the caudate nucleus and the putamen. ... The basal ganglia system is a pair and symmetrical major cerebral system that has only recently been recognized. ...


The term neostriatum was forged by comparative anatomists comparing the subcortical structures between vertebrates because it was thought to be a phylogenetically newer section of the corpus striatum.


Structure

The dorsal striatum forms a continuous and large mass, topographically separated by the internal capsule into the caudate nucleus medially, the putamen laterally and the fundus below, linking the two preceding ventrally; but a single entity. The striatum is homogeneous in term of neuronal components. It is built up of 4 neuronal types:[1] Grays Fig. ... The putamen is a structure in the middle of the brain, forming the striatum together with the caudate nucleus. ... In anatomy, the stomach (in ancient Greek στόμαχος) is an organ in the alimentary canal used to digest food. ... Look up Homogeneous in Wiktionary, the free dictionary. ... Neurons (also called nerve cells) are the primary cells of the nervous system. ...

  • spiny neurons relatively close from the pyramidal neurons of the cortex due to the presence of spines with spine apparatus (acanthodendritic neurons), and make up 96% of the striatum.
  • Leptodendritic (Deiter's) neurons(2%) with large, poorly bifurcated, arborisations looking like pallidonigral neurons.
  • Spidery cholinergic interneurons(1%) morphologically entirely different from those observed in rodents (which must lead to very careful interspecific correlations).In primates they are the tonically Active Neurons (TANs). These briefly stop firing in concomitance to behaviourally salient situations and reward-related events.
  • GABAergic parvalbumin expressing interneurons, which are fast-spiking, and express dopamine receptors
  • GABAergic calretinin expressing interneurons
  • GABAergic somatostatin expressing interneurons, which are low threshold spiking and express dopamine receptors

The chemical compound acetylcholine, often abbreviated as ACh, was the first neurotransmitter to be identified. ... An interneuron is a neuron that communicates only to other neurons. ... ... Dopamine is a phenethylamine naturally produced by the human body. ... Dopamine is a phenethylamine naturally produced by the human body. ...

Organization

The striatum is spatially organized according to several levels.


Anatomical subdivisions and territories

The dorsal striatum is a single entity closed and continuous with a toric topology. The observable anatomical subdivisions of the dorsal striatum (caudate nucleus and putamen) essentially induced by the internal capsule do not completely overlap with now accepted anatomo-functional subdivisions. The selective distribution of the axonal terminal arborisations of cortical sources differentiate the sensorimotor striatum, mainly putaminal but located in its dorsal part and in the lateroinferior part of the caudate. A great part of the remaining of the volume (essentially caudate) receiving from axonal endings from the frontal, parietal, temporal cortex forms the associative striatum. The separation between these two territories is rather clearcut and observable using calbindin immunochemistry. A third entity, the most inferomedial, raises more problems as there is no general agreement about its border with the associative striatum.


The ventral striatum is clearly delineated by tracing the subicular territory. This corresponds to the olfactory tubercle and the nucleus accumbens, which is not a nucleus and is a striatal part made up of striatal elements. The nucleus accumbens (NAcc), also known as the accumbens nucleus or as the nucleus accumbens septi (Latin for nucleus leaning against the septum), is a collection of neurons located where the head of the caudate and the anterior portion of the putamen meet just lateral to the septum pellucidum. ...


"Compartments"

Immunochemical characteristics particularly acetyl cholinesterase differentiated "compartments" called 'striosomes' and matrix in which 'matrisomes'are sometimes differentiated.


Afferent Connections

The most important afferent in terms of quantity of axons is the corticostriatal connection. Many parts of the neocortex innervate the dorsal striatum. The cortical pyramidal neurons projecting to the striatum are located in the lamina V. They end mainly on the spines of the spiny neurons. They are (glutamatergic), exciting striatal neurons. Another well known afferent is the nigrostriatal connection arising from the neurons of the substantia nigra pars compacta. While cortical axons synapse mainly on spine heads of spiny neurons, nigral axons synapse mainly on spine shafts. The thalamostriatal afferent essentially comes in primates from the central region (center median parafascicular complex see primate basal ganglia system).This is glutamatergic. The participation of truly intralaminar neurons is much more limited. The striatum receives afferents from other elements of the basal ganglia such as the subthalamic nucleus (glutamatergic) or the external globus pallidus (GABAergic). A pyramidal cell (or pyramidal neuron) is a multipolar neuron located in the hippocampus and cerebral cortex. ... Glutamic acid or glutamate (the anionic form of glutamic acid) is one of the 20 most common natural amino acids. ... The substantia nigra, (Latin for black substance, Soemering) or locus niger is a heterogeneous portion of the midbrain, separating the pes (foot) from the tegmentum (covering), and a major element of the basal ganglia system. ... The basal ganglia system is a pair and symmetrical major cerebral system that has only recently been recognized. ...


Targets

The main efferent target of the striatum is the pallidonigral set.The basal ganglia core is made up of the striatum and its direct targets through the striato-pallidonigral bundle. The striato-pallidonigral bundle is a very dense bundle of fewly myelinated axons giving the whitish aspect to the set. This comprises successively the external globus pallidus (GPe), the internal globus pallidus (GPi), the pars compacta of the substantia nigra (SNc) and the substantia nigra pars reticulata (SNr). This set is made up of the same genus of neurons. Its neurons are inhibited by GABAergic synapses from the dorsal striatum. Among these targets, one does not send axons outside the system (GPe, thus a regulator). Another sends axons to the superior colliculus. Two others are the bases of basal ganglia system output to the thalamus forming two separate channels: one through the internal segment of the globus pallidus] to VO and from there to the cortical SMA and another through the substantia nigra to VA and from there to the frontal and the oculomotor cortex . 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, Soemering) or locus niger is a heterogeneous portion of the midbrain, separating the pes (foot) from the tegmentum (covering), and a major element of the basal ganglia system. ... The substantia nigra, (Latin for black substance, Soemering) or locus niger is a heterogeneous portion of the midbrain, separating the pes (foot) from the tegmentum (covering), and a major element of the basal ganglia system. ... The superior colliculus is part of the brain that sits below the thalamus and surrounds the pineal gland in the mesencephalon of vertebrate brains. ... The globus pallidus (Latin for pale body) is a sub-cortical structure in the brain. ... The substantia nigra, (Latin for black substance, Soemering) or locus niger is a heterogeneous portion of the midbrain, separating the pes (foot) from the tegmentum (covering), and a major element of the basal ganglia system. ...


Function

Metabotropic dopamine receptors are present both on spiny neurons and on cortical axon terminals. Second messenger cascades triggered by activation of these dopamine receptors can modulate pre- and postsynaptic function, both in the short term and in the long term. The striatum is best known for its role in the planning and modulation of movement pathways but is also involved in a variety of other cognitive processes involving executive function. In humans the striatum is activated by stimuli associated with reward, but also by aversive, novel, unexpected or intense stimuli, and cues associated with such events. Recent fMRI evidence[citation needed] suggests that the common property linking these stimuli, to which the striatum is reacting, is saliency under the conditions of presentation. A number of other brain areas and circuits are also related to reward such as frontal areas. Metabotropic receptor is a transmembrane receptor, which starts some intracellular biochemical cascade after its activation by an agonistic ligand. ... The dopamine receptors are a class of G-protein coupled receptors with dopamine as their endogenous ligand. ... In biology, second messengers are low-weight diffusible molecules that are used in signal transduction to relay signals within a cell. ... The executive system is a theorised cognitive system in psychology that controls and manages other cognitive processes. ... Functional Magnetic Resonance Imaging (or fMRI) describes the use of MRI to measure hemodynamic signals related to neural activity in the brain or spinal cord of humans or other animals. ...


For sources regarding saliency of the reward pathway(thought to be related to dopamine) one can look to the work of Dr John Salmone (storrs Connecticut early to late 90's) and wolfram Schultz. The ventral tegmental Da neurons that innervate portions of the striatum have long been accepted to be the site of rewarding feeling. Intracranial stimulation ICS studies from the 60's show implants in this brain area will elicit bar pressing form rats for many hours at a time. However the collective works of researchers in the 90's show that blocking Da receptors does not remove rewarding sensations, rather it effects how much the animal is willing to work, more motivation to seek reward rather than reward itself.


Pathology

Parkinson's disease results in loss of dopaminergic innervation to the striatum (and other basal ganglia) and to the cascade of subsequent consequences. The lesion of the striatum is also involved in the Huntington's disease, choreas, choreoathetosis and dyskinesias. It is also thought that addiction involves plasticity at striatal synapses. Addiction is a chronic or recurrent condition proposed to be precipitated by one or more of the following: genetic, biological/pharmacological and social factors. ...


References

  • Aosaki T, Kiuchi K & Kawaguchi Y (1998) Dopamine D1-like receptor activation excites rat striatal large aspiny neurons in vitro. J Neurosci 15, 5180–90
  • Apicella P (2002) Tonically active neurons in the primate striatum and their role in the processing of information about motivationally relevant events. Eur J Neurosci 16, 2017–26
  • Cossette, M., Lecomte, F. and Partent, A. (2005) Morphology and distribution of dopaminergic intrinsic to human striatum. J. Chem. Neuroanat. 29: 1-11
  • Holt DJ, Graybiel AM & Saper CB (1997) Neurochemical architecture of the human striatum. J Comp Neurol 21, 1–25
  • Morris G, Arkadir D, Nevet A, Vaadia E & Bergman H (2004) Coincident but distinct messages of midbrain dopamine and striatal tonically active neurons. Neuron 8, 133–43
  • Tepper JM & Bolam JP (2004) Functional diversity and specificity of neostriatal interneurons. Curr Opin Neurobiol 14, 685–92
  • Yamada H, Matsumoto N & Kimura M (2004) Tonically active neurons in the primate caudate nucleus and putamen differentially encode instructed motivational outcomes of action. J Neurosci 7, 3500–10
  • Yelnik, J., François, C., Percheron, G., Tandé, D. (1991) Morphological taxonomy of the neurons of the primate striatum. J. Comp. Neurol. 313:273-294
  • Zink, CF, Pagnoni G, Martin-Skurski ME, Chappelow JC, & Berns GS (2004). Human striatal responses to monetary reward depend on saliency. Neuron 42, 509-17

See also

Human brain image constructed from MRI data // Brain (neural tube) Brainstem (rhombencephalon),(mesencephalon) Rhombencephalon (hindbrain) Metencephalon pons fourth ventricle cerebellum cerebellar vermis cerebellar hemispheres anterior lobe posterior lobe flocculonodular lobe cerebellar nuclei fastigial nucleus globose nucleus emboliform nucleus dentate nucleus Myelencephalon medulla oblongata medullary pyramids Mesencephalon (midbrain) tectum inferior colliculi...

External links


  Results from FactBites:
 
Striatum - Wikipedia, the free encyclopedia (708 words)
In the brain, the striatum or neostriatum is a subcortical part of the telencephalon consisting of the caudate nucleus and the putamen.
The main efferent target of the striatum is the globus pallidus, which is primarily inhibited by GABAergic synapses from the striatum.
The main afferent region to the striatum is neocortex.
Basal ganglia - Wikipedia, the free encyclopedia (1422 words)
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 anatomical link of the striatum with its primary targets, the pallidum and the substantia nigra was later discovered.
The "striatum" and "external segment of the globus pallidus" in primates are called the "paleostriatum augmentatum" and "paleostriatum primitivum" respectively in birds.
  More results at FactBites »

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m