The striatum, or corpus striatum (also called the striate nucleus), is a
nucleus
Nucleus ( : nuclei) is a Latin word for the seed inside a fruit. It most often refers to:
* Atomic nucleus, the very dense central region of an atom
*Cell nucleus, a central organelle of a eukaryotic cell, containing most of the cell's DNA
Nucl ...
(a cluster of
neurons) in the
subcortical
The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex mostly consists of the six-layered neocortex, with just 10% consisting of ...
basal ganglia
The basal ganglia (BG), or basal nuclei, are a group of subcortical nuclei, of varied origin, in the brains of vertebrates. In humans, and some primates, there are some differences, mainly in the division of the globus pallidus into an exter ...
of the
forebrain
In the anatomy of the brain of vertebrates, the forebrain or prosencephalon is the rostral (forward-most) portion of the brain. The forebrain (prosencephalon), the midbrain (mesencephalon), and hindbrain (rhombencephalon) are the three primary b ...
. The striatum is a critical component of the
motor and
reward
Reward may refer to:
Places
* Reward (Shelltown, Maryland), a historic home in Shelltown Maryland
* Reward, California (disambiguation)
* Reward-Tilden's Farm, a historic home in Chestertown Maryland
Arts, entertainment, and media
* "Rewa ...
systems; receives
glutamatergic
Glutamatergic means "related to glutamate". A glutamatergic agent (or drug) is a chemical that directly modulates the excitatory amino acid (glutamate/aspartate) system in the body or brain. Examples include excitatory amino acid receptor agonis ...
and
dopaminergic
Dopaminergic means "related to dopamine" (literally, "working on dopamine"), dopamine being a common neurotransmitter. Dopaminergic substances or actions increase dopamine-related activity in the brain. Dopaminergic brain pathways facilitate do ...
inputs from different sources; and serves as the primary input to the rest of the basal ganglia.
Functionally, the striatum coordinates multiple aspects of
cognition
Cognition refers to "the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses". It encompasses all aspects of intellectual functions and processes such as: perception, attention, though ...
, including both motor and action
planning,
decision-making,
motivation,
reinforcement
In behavioral psychology, reinforcement is a consequence applied that will strengthen an organism's future behavior whenever that behavior is preceded by a specific antecedent stimulus. This strengthening effect may be measured as a higher freq ...
, and
reward
Reward may refer to:
Places
* Reward (Shelltown, Maryland), a historic home in Shelltown Maryland
* Reward, California (disambiguation)
* Reward-Tilden's Farm, a historic home in Chestertown Maryland
Arts, entertainment, and media
* "Rewa ...
perception.
The striatum is made up of the
caudate nucleus
The caudate nucleus is one of the structures that make up the corpus striatum, which is a component of the basal ganglia in the human brain. While the caudate nucleus has long been associated with motor processes due to its role in Parkinson's d ...
and the
lentiform nucleus. The lentiform nucleus is made up of the larger
putamen
The putamen (; from Latin, meaning "nutshell") is a round structure located at the base of the forebrain (telencephalon). The putamen and caudate nucleus together form the dorsal striatum. It is also one of the structures that compose the basal ...
, and the smaller
globus pallidus
The globus pallidus (GP), also known as paleostriatum or dorsal pallidum, is a subcortical structure of the brain. It consists of two adjacent segments, one external, known in rodents simply as the globus pallidus, and one internal, known in rod ...
.
Strictly speaking the globus pallidus is part of the striatum. It is common practice, however, to implicitly exclude the globus pallidus when referring to striatal structures.
In
primates, the striatum is divided into a ventral striatum, and a dorsal striatum, subdivisions that are based upon function and connections. The
ventral
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
striatum consists of the
nucleus accumbens
The nucleus accumbens (NAc or NAcc; also known as the accumbens nucleus, or formerly as the ''nucleus accumbens septi'', Latin for "nucleus adjacent to the septum") is a region in the basal forebrain rostral to the preoptic area of the hypotha ...
and the
olfactory tubercle
The olfactory tubercle (OT), also known as the tuberculum olfactorium, is a multi-sensory processing center that is contained within the olfactory cortex and ventral striatum and plays a role in reward cognition. The OT has also been shown to ...
. The
dorsal
Dorsal (from Latin ''dorsum'' ‘back’) may refer to:
* Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism
* Dorsal, positioned on top of an aircraft's fuselage
* Dorsal co ...
striatum consists of the
caudate nucleus
The caudate nucleus is one of the structures that make up the corpus striatum, which is a component of the basal ganglia in the human brain. While the caudate nucleus has long been associated with motor processes due to its role in Parkinson's d ...
and the
putamen
The putamen (; from Latin, meaning "nutshell") is a round structure located at the base of the forebrain (telencephalon). The putamen and caudate nucleus together form the dorsal striatum. It is also one of the structures that compose the basal ...
. A
white matter,
nerve tract
A nerve tract is a bundle of nerve fibers (axons) connecting nuclei of the central nervous system. In the peripheral nervous system this is known as a nerve, and has associated connective tissue. The main nerve tracts in the central nervous syst ...
(the
internal capsule) in the dorsal striatum separates the
caudate nucleus
The caudate nucleus is one of the structures that make up the corpus striatum, which is a component of the basal ganglia in the human brain. While the caudate nucleus has long been associated with motor processes due to its role in Parkinson's d ...
and the
putamen
The putamen (; from Latin, meaning "nutshell") is a round structure located at the base of the forebrain (telencephalon). The putamen and caudate nucleus together form the dorsal striatum. It is also one of the structures that compose the basal ...
.
Anatomically, the term ''striatum'' describes its striped (striated) appearance of grey-and-white matter.
Structure
The striatum is the largest structure of the
basal ganglia
The basal ganglia (BG), or basal nuclei, are a group of subcortical nuclei, of varied origin, in the brains of vertebrates. In humans, and some primates, there are some differences, mainly in the division of the globus pallidus into an exter ...
. The striatum is divided into a ventral and a dorsal subdivision, based upon function and connections.
The ventral striatum is composed of the
nucleus accumbens
The nucleus accumbens (NAc or NAcc; also known as the accumbens nucleus, or formerly as the ''nucleus accumbens septi'', Latin for "nucleus adjacent to the septum") is a region in the basal forebrain rostral to the preoptic area of the hypotha ...
and the
olfactory tubercle
The olfactory tubercle (OT), also known as the tuberculum olfactorium, is a multi-sensory processing center that is contained within the olfactory cortex and ventral striatum and plays a role in reward cognition. The OT has also been shown to ...
.
The nucleus accumbens is made up of the
nucleus accumbens core and the
nucleus accumbens shell, which differ by neural populations. The olfactory tubercle receives input from the
olfactory bulb
The olfactory bulb (Latin: ''bulbus olfactorius'') is a neural structure of the vertebrate forebrain involved in olfaction, the sense of smell. It sends olfactory information to be further processed in the amygdala, the orbitofrontal cortex (OF ...
but has not been shown to play a role in
processing smell.
In non-primate species, the
islands of Calleja are included.
The ventral striatum is associated with the limbic system and has been implicated as a vital part of the
circuitry
An electronic circuit is composed of individual electronic components, such as resistors, transistors, capacitors, inductors and diodes, connected by conductive wires or traces through which electric current can flow. It is a type of electrical ...
for decision making and reward-related behavior.
The dorsal striatum is composed of the
caudate nucleus
The caudate nucleus is one of the structures that make up the corpus striatum, which is a component of the basal ganglia in the human brain. While the caudate nucleus has long been associated with motor processes due to its role in Parkinson's d ...
and the
putamen
The putamen (; from Latin, meaning "nutshell") is a round structure located at the base of the forebrain (telencephalon). The putamen and caudate nucleus together form the dorsal striatum. It is also one of the structures that compose the basal ...
.
Staining
Staining is a technique used to enhance contrast in samples, generally at the microscopic level. Stains and dyes are frequently used in histology (microscopic study of biological tissues), in cytology (microscopic study of cells), and in the ...
can differentiate the striatum into two distinct compartments of
striosomes or ''patches'', and a surrounding
matrix; this is particularly evident on the components of
acetylcholinesterase
Acetylcholinesterase ( HGNC symbol ACHE; EC 3.1.1.7; systematic name acetylcholine acetylhydrolase), also known as AChE, AChase or acetylhydrolase, is the primary cholinesterase in the body. It is an enzyme that catalyzes the breakdown of acet ...
and
calbindin
Calbindins are three different calcium-binding proteins: calbindin, calretinin and S100G. They were originally described as vitamin D-dependent calcium-binding proteins in the intestine and kidney in the chick and mammals. They are now classifie ...
. More studies have been carried out on the dorsal striatum but the compartments have also been identified in the ventral striatum. In the dorsal striatum striosomes make up 10-15 per cent of the striatal volume.
Cell types
Types of cells in the striatum include:
*
Medium spiny neurons (MSNs), which are the principal neurons of the striatum.
They are
GABAergic and, thus, are classified as inhibitory neurons. Medium spiny projection neurons comprise 95% of the total neuronal population of the human striatum.
Medium spiny neurons have two
characteristic types:
D1-type
The D1-like receptors are a subfamily of dopamine receptors that bind the endogenous neurotransmitter dopamine. The D1-like subfamily consists of two G protein–coupled receptors that are coupled to Gs and mediate excitatory neurotransmission
...
MSNs and
D2-type
The D2-like receptors are a subfamily of dopamine receptors that bind the endogenous neurotransmitter dopamine. The D2-like subfamily consists of three G-protein coupled receptors that are coupled to Gi/Go and mediate inhibitory neurotransmissio ...
MSNs.
A subpopulation of MSNs contain both D1-type and D2-type receptors, with approximately 40% of striatal MSNs expressing both
DRD1
Dopamine receptor D1, also known as DRD1. It is one of the two types of D1-like receptor family - receptors D1 and D5. It is a protein that in humans is encoded by the DRD1 gene.
Tissue distribution
D1 receptors are the most abundant kind of d ...
and
DRD2
Dopamine receptor D2, also known as D2R, is a protein that, in humans, is encoded by the ''DRD2'' gene. After work from Paul Greengard's lab had suggested that dopamine receptors were the site of action of antipsychotic drugs, several groups, i ...
mRNA.
*
Cholinergic
Cholinergic agents are compounds which mimic the action of acetylcholine and/or butyrylcholine. In general, the word "choline" describes the various quaternary ammonium salts containing the ''N'',''N'',''N''-trimethylethanolammonium cation. F ...
interneurons release acetylcholine, which has a variety of important effects in the striatum. In humans, other primates, and rodents, these interneurons respond to salient environmental stimuli with stereotyped responses that are temporally aligned with the responses of dopaminergic neurons of the
substantia nigra
The substantia nigra (SN) is a basal ganglia structure located in the midbrain that plays an important role in reward and movement. ''Substantia nigra'' is Latin for "black substance", reflecting the fact that parts of the substantia nigra appe ...
. The large aspiny cholinergic interneurons themselves are affected by dopamine through
D5 dopamine receptors. Dopamine also directly controls communication between cholinergic interneurons.
* There are many types of GABAergic interneurons.
The best known are
parvalbumin expressing interneurons, also known as
fast-spiking interneurons, which participate in powerful
feedforward inhibition of principal neurons. Also, there are GABAergic interneurons that express
tyrosine hydroxylase,
somatostatin,
nitric oxide synthase and
neuropeptide-y. Recently, two types of neuropeptide-y expressing GABAergic interneurons have been described in detail, one of which translates synchronous activity of cholinergic interneurons into inhibition of principal neurons. These
neurons of the striatum are not distributed evenly.
There are two regions of
neurogenesis in the brain – the
subventricular zone
The subventricular zone (SVZ) is a region situated on the outside wall of each lateral ventricle of the vertebrate brain. It is present in both the embryonic and adult brain. In embryonic life, the SVZ refers to a secondary proliferative zone ...
in the
lateral ventricles, and the
dentate gyrus
The dentate gyrus (DG) is part of the hippocampal formation in the temporal lobe of the brain, which also includes the hippocampus and the subiculum. The dentate gyrus is part of the hippocampal trisynaptic circuit and is thought to contribut ...
in the
hippocampal formation
The hippocampal formation is a compound structure in the medial temporal lobe of the brain. It forms a c-shaped bulge on the floor of the temporal horn of the lateral ventricle. There is no consensus concerning which brain regions are encompassed ...
.
Neuroblasts that form in the lateral ventricle adjacent to the striatum, integrate in the striatum.
This has been noted in the human striatum following an
ischemic stroke. Injury caused to the striatum stimulates the migration of neuroblasts from the subventricular zone, to the striatum, where they differentiate into adult neurons.
The normal passage of SVZ neuroblasts is to the
olfactory bulb
The olfactory bulb (Latin: ''bulbus olfactorius'') is a neural structure of the vertebrate forebrain involved in olfaction, the sense of smell. It sends olfactory information to be further processed in the amygdala, the orbitofrontal cortex (OF ...
but this traffic is diverted to the striatum after an ischemic stroke. However, few of the new developed neurons survive.
Inputs
The largest connection is from the
cortex, in terms of cell axons. Many parts of the
neocortex innervate the dorsal striatum. The cortical
pyramidal neurons
Pyramidal cells, or pyramidal neurons, are a type of multipolar neuron found in areas of the brain including the cerebral cortex, the hippocampus, and the amygdala. Pyramidal neurons are the primary excitation units of the mammalian prefrontal co ...
projecting to the striatum are located in layers II-VI, with the most dense projections come from layer V. They end mainly on the
dendritic spines of the spiny neurons. They are
glutamatergic
Glutamatergic means "related to glutamate". A glutamatergic agent (or drug) is a chemical that directly modulates the excitatory amino acid (glutamate/aspartate) system in the body or brain. Examples include excitatory amino acid receptor agonis ...
, exciting striatal neurons.
The striatum is seen as having its own internal microcircuitry.
The ventral striatum receives direct input from multiple regions in the
cerebral cortex
The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex mostly consists of the six-layered neocortex, with just 10% consisting of ...
and limbic structures such as the
amygdala
The amygdala (; plural: amygdalae or amygdalas; also '; Latin from Greek, , ', 'almond', 'tonsil') is one of two almond-shaped clusters of nuclei located deep and medially within the temporal lobes of the brain's cerebrum in complex verte ...
,
thalamus, and
hippocampus, as well as the
entorhinal cortex and the
inferior temporal gyrus
The inferior temporal gyrus is one of three gyri of the temporal lobe and is located below the middle temporal gyrus, connected behind with the inferior occipital gyrus; it also extends around the infero-lateral border on to the inferior surface ...
.
Its primary input is to the
basal ganglia
The basal ganglia (BG), or basal nuclei, are a group of subcortical nuclei, of varied origin, in the brains of vertebrates. In humans, and some primates, there are some differences, mainly in the division of the globus pallidus into an exter ...
system. Additionally, the
mesolimbic pathway
The mesolimbic pathway, sometimes referred to as the reward pathway, is a dopaminergic pathway in the brain. The pathway connects the ventral tegmental area in the midbrain to the ventral striatum of the basal ganglia in the forebrain. The ventral ...
projects from the
ventral tegmental area to the
nucleus accumbens
The nucleus accumbens (NAc or NAcc; also known as the accumbens nucleus, or formerly as the ''nucleus accumbens septi'', Latin for "nucleus adjacent to the septum") is a region in the basal forebrain rostral to the preoptic area of the hypotha ...
of the ventral striatum.
Another well-known afferent is the
nigrostriatal The nigrostriatal pathway is a bilateral dopaminergic pathway in the brain that connects the substantia nigra pars compacta (SNc) in the midbrain with the dorsal striatum (i.e., the caudate nucleus and putamen) in the forebrain. It is one of the fou ...
connection arising from the neurons of the
substantia nigra
The substantia nigra (SN) is a basal ganglia structure located in the midbrain that plays an important role in reward and movement. ''Substantia nigra'' is Latin for "black substance", reflecting the fact that parts of the substantia nigra appe ...
pars compacta. While cortical axons synapse mainly on spine heads of spiny neurons, nigral axons synapse mainly on spine shafts.
In primates, the thalamostriatal afferent comes from the central median-parafascicular complex of the
thalamus (see
primate basal ganglia system
The basal ganglia form a major brain system in all species of vertebrates, but in primates (including humans) there are special features that justify a separate consideration. As in other vertebrates, the primate basal ganglia can be divided into ...
). This afferent is glutamatergic. The participation of truly intralaminar neurons is much more limited.
The striatum also receives afferents from other elements of the basal ganglia such as the
subthalamic nucleus
The subthalamic nucleus (STN) is a small lens-shaped nucleus in the brain where it is, from a functional point of view, part of the basal ganglia system. In terms of anatomy, it is the major part of the subthalamus. As suggested by its name, the s ...
(glutamatergic) or the
external globus pallidus
The external globus pallidus (GPe or lateral globus pallidus) combines with the internal globus pallidus (GPi) to form the globus pallidus, an anatomical subset of the basal ganglia. Globus pallidus means "pale globe" in Latin, indicating its appea ...
(
GABAergic).
Targets
The primary outputs of the ventral striatum project to the
ventral pallidum
The ventral pallidum (VP) is a structure within the basal ganglia of the brain. It is an output nucleus whose fibres project to thalamic nuclei, such as the ventral anterior nucleus, the ventral lateral nucleus, and the medial dorsal nucleus.
T ...
, then the
medial dorsal nucleus of the
thalamus, which is part of the
frontostriatal circuit. Additionally, the ventral striatum projects to the
globus pallidus
The globus pallidus (GP), also known as paleostriatum or dorsal pallidum, is a subcortical structure of the brain. It consists of two adjacent segments, one external, known in rodents simply as the globus pallidus, and one internal, known in rod ...
, and substantia nigra pars reticulata. Some of its other outputs include projections to the
extended amygdala The extended amygdala is a macrostructure in the brain that is involved in reward cognition and defined by connectivity and neurochemical staining. It includes the central medial amygdala, sublenticular substantia innominata, and the bed nucleus o ...
,
lateral hypothalamus, and
pedunculopontine nucleus
The pedunculopontine nucleus (PPN) or pedunculopontine tegmental nucleus (PPT or PPTg) is a collection of neurons located in the upper pons in the brainstem. It lies caudal to the substantia nigra and adjacent to the superior cerebellar peduncle. ...
.
Striatal outputs from both the dorsal and ventral components are primarily composed of
medium spiny neuron
Medium spiny neurons (MSNs), also known as spiny projection neurons (SPNs), are a special type of GABAergic inhibitory cell representing 95% of neurons within the human striatum, a basal ganglia structure. Medium spiny neurons have two primary ...
s (MSNs), a type of
projection neuron, which have two primary
phenotypes: "indirect" MSNs that express
D2-like receptor
The D2-like receptors are a subfamily of dopamine receptors that bind the endogenous neurotransmitter dopamine. The D2-like subfamily consists of three G-protein coupled receptors that are coupled to Gi/Go and mediate inhibitory neurotransmission ...
s and "direct" MSNs that express
D1-like receptor
The D1-like receptors are a subfamily of dopamine receptors that bind the endogenous neurotransmitter dopamine. The D1-like subfamily consists of two G protein–coupled receptors that are coupled to Gs and mediate excitatory neurotransmission
...
s.
The main nucleus of the basal ganglia is the striatum which projects directly to the globus pallidus via a pathway of
striatopallidal fibers. The striato-pallidal pathway has a whitish appearance due to the myelinated fibers. This projection comprises successively the external globus pallidus (GPe), the internal globus pallidus (GPi), the
pars compacta
The pars compacta (SNpc) is a portion of the ''substantia nigra'', located in the midbrain. It is formed by dopaminergic neurons and located medial to the pars reticulata. Parkinson's disease is characterized by the death of dopaminergic neuro ...
of the
substantia nigra
The substantia nigra (SN) is a basal ganglia structure located in the midbrain that plays an important role in reward and movement. ''Substantia nigra'' is Latin for "black substance", reflecting the fact that parts of the substantia nigra appe ...
(SNc), and the
pars reticulata
The pars reticulata (SNpr) is a portion of the substantia nigra and is located lateral to the pars compacta. Most of the neurons that project out of the pars reticulata are inhibitory GABAergic neurons (i.e., these neurons release GABA, which is ...
of substantia nigra (SNr). The neurons of this projection are inhibited by GABAergic synapses from the dorsal striatum. Among these targets, the GPe does not send axons outside the system. Others send axons to the
superior colliculus. Two others comprise the output to the thalamus, forming two separate channels: one through the internal segment of the globus pallidus to the ventral oralis nuclei of the thalamus and from there to the cortical
supplementary motor area and another through the substantia nigra to the ventral anterior nuclei of the thalamus and from there to the
frontal cortex
The frontal lobe is the largest of the four major lobes of the brain in mammals, and is located at the front of each cerebral hemisphere (in front of the parietal lobe and the temporal lobe). It is parted from the parietal lobe by a groove betw ...
and the occulomotor cortex.
Blood supply
Deep penetrating
striate arteries supply blood to the striatum. These arteries include the
recurrent artery of Heubner arising from the
anterior cerebral artery, and the
lenticulostriate arteries The lenticulostriate arteries, anterolateral central arteries, or antero-lateral ganglionic branches are a group of small arteries arising from the initial part M1 of the middle cerebral artery that supply the basal ganglia.
Structure
The lenticul ...
arising from the
middle cerebral artery.
Function
The ventral striatum, and the
nucleus accumbens
The nucleus accumbens (NAc or NAcc; also known as the accumbens nucleus, or formerly as the ''nucleus accumbens septi'', Latin for "nucleus adjacent to the septum") is a region in the basal forebrain rostral to the preoptic area of the hypotha ...
in particular, primarily mediates
reward
Reward may refer to:
Places
* Reward (Shelltown, Maryland), a historic home in Shelltown Maryland
* Reward, California (disambiguation)
* Reward-Tilden's Farm, a historic home in Chestertown Maryland
Arts, entertainment, and media
* "Rewa ...
, cognition,
reinforcement
In behavioral psychology, reinforcement is a consequence applied that will strengthen an organism's future behavior whenever that behavior is preceded by a specific antecedent stimulus. This strengthening effect may be measured as a higher freq ...
, and
motivational salience
Motivational salience is a cognitive process and a form of attention that ''motivates'' or propels an individual's behavior towards or away from a particular object, perceived event or outcome. Motivational salience regulates the intensity of b ...
, whereas the dorsal striatum primarily mediates cognition involving
motor function
Motor control is the regulation of movement in organisms that possess a nervous system. Motor control includes reflexes as well as directed movement.
To control movement, the nervous system must integrate multimodal sensory information (both ...
, certain
executive functions (e.g.,
inhibitory control
Inhibitory control, also known as response inhibition, is a cognitive process – and, more specifically, an executive function – that permits an individual to inhibit their impulses and natural, habitual, or dominant behavioral res ...
and
impulsivity), and
stimulus-response learning;
there is a small degree of overlap, as the dorsal striatum is also a component of the
reward system that, along with the
nucleus accumbens core, mediates the encoding of new motor programs associated with future reward acquisition (e.g., the
conditioned motor response to a reward cue).
Metabotropic
A metabotropic receptor, also referred to by the broader term G-protein-coupled receptor, is a type of membrane receptor that initiates a number of metabolic steps to modulate cell activity. The nervous system utilizes two types of receptors: m ...
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.
In humans, the striatum is activated by stimuli associated with reward, but also by
aversive,
novel,
unexpected, or intense
stimuli
A stimulus is something that causes a physiological response. It may refer to:
*Stimulation
**Stimulus (physiology), something external that influences an activity
**Stimulus (psychology), a concept in behaviorism and perception
*Stimulus (economi ...
, and cues associated with such events.
fMRI evidence suggests that the common property linking these stimuli, to which the striatum is reacting, is
salience under the conditions of presentation.
A number of other brain areas and circuits are also related to reward, such as frontal areas. Functional maps of the striatum reveal interactions with widely distributed regions of the cerebral cortex important to a diverse range of functions.
The interplay between the striatum and the
prefrontal cortex is relevant for behavior, particularly adolescent development as proposed by the
dual systems model
The dual systems model, also known as the maturational imbalance model, is a theory arising from developmental cognitive neuroscience which posits that increased risk-taking during adolescence is a result of a combination of heightened reward sensi ...
.
Clinical significance
Parkinson's disease and other movement disorders
Parkinson's disease results in loss of dopaminergic innervation to the dorsal striatum (and other basal ganglia) and a cascade of consequences.
Atrophy
Atrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations (which can destroy the gene to build up the organ), poor nourishment, poor circulation, loss of hormonal support, loss of nerve supply t ...
of the striatum is also involved in
Huntington's disease, and
movement disorders such as
chorea
Chorea (or choreia, occasionally) is an abnormal involuntary movement disorder, one of a group of neurological disorders called dyskinesias. The term ''chorea'' is derived from the grc, χορεία ("dance"; see choreia), as the quick movemen ...
,
choreoathetosis, and
dyskinesias.
These have also been described as ''circuit disorders'' of the basal ganglia.
Addiction
Addiction
Addiction is a neuropsychological disorder characterized by a persistent and intense urge to engage in certain behaviors, one of which is the usage of a drug, despite substantial harm and other negative consequences. Repetitive drug use oft ...
, a disorder of the brain's
reward system, arises through the
overexpression of
DeltaFosB (ΔFosB), a
transcription factor, in the
D1-type
The D1-like receptors are a subfamily of dopamine receptors that bind the endogenous neurotransmitter dopamine. The D1-like subfamily consists of two G protein–coupled receptors that are coupled to Gs and mediate excitatory neurotransmission
...
medium spiny neuron
Medium spiny neurons (MSNs), also known as spiny projection neurons (SPNs), are a special type of GABAergic inhibitory cell representing 95% of neurons within the human striatum, a basal ganglia structure. Medium spiny neurons have two primary ...
s of the
ventral striatum. ΔFosB is an
inducible gene
Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product that enables it to produce end products, protein or non-coding RNA, and ultimately affect a phenotype, as the final effect. ...
which is increasingly expressed in the
nucleus accumbens
The nucleus accumbens (NAc or NAcc; also known as the accumbens nucleus, or formerly as the ''nucleus accumbens septi'', Latin for "nucleus adjacent to the septum") is a region in the basal forebrain rostral to the preoptic area of the hypotha ...
as a result of repeatedly
overdosing
A drug overdose (overdose or OD) is the ingestion or application of a drug or other substance in quantities much greater than are recommended. on an addictive drug or overexposure to other addictive stimuli.
Table 1
/ref>
Bipolar disorder
An association has been observed between striatal expression of variants of the PDE10A
cAMP and cAMP-inhibited cGMP 3',5'-cyclic phosphodiesterase 10A is an enzyme that in humans is encoded by the ''PDE10A'' gene.
Various cellular responses are regulated by the second messengers cAMP and cGMP. Phosphodiesterases, such as PDE10A, ...
gene and some bipolar I disorder
Bipolar I disorder (BD-I; pronounced "type one bipolar disorder") is a type of bipolar spectrum disorder characterized by the occurrence of at least one manic episode, with or without mixed or psychotic features. Most people also, at other tim ...
patients. Variants of other genes, DISC1 and GNAS, have been associated with bipolar II disorder.
Autism spectrum disorder
Autism spectrum disorder
The autism spectrum, often referred to as just autism or in the context of a professional diagnosis autism spectrum disorder (ASD) or autism spectrum condition (ASC), is a neurodevelopmental condition (or conditions) characterized by difficulti ...
(ASD) is characterized by cognitive inflexibility and poor understanding of social systems. This inflexible behavior originates in defects in the pre-frontal cortex as well as the striatal circuits. The defects in the striatum seem to specifically contribute to the motor, social and communication impairments seen in ASD patients. In mice which have an ASD-like phenotype induced via the overexpression of the eukaryotic initiation of translation factor 4E, it has been shown that these defects seem to stem from the reduced ability to store and process information in the striatum, which leads to the difficulty seen in forming new motor patterns, as well as disengaging from existing ones.
Dysfunction
Dysfunction in the ventral striatum can lead to a variety of disorders, most notably, depression and obsessive-compulsive disorder. Because of its involvement in reward pathways, the ventral striatum has also been implicated in playing a critical role in addiction. It has been well established that the ventral striatum is strongly involved in mediating the reinforcing effects of drugs, especially stimulants, through dopaminergic stimulation.
History
In the seventeenth and eighteenth centuries, the term "corpus striatum" was used to designate many distinct, deep, infracortical elements of the hemisphere. Etymologically it is derived from (Latin) "striatus" = "grooved, striated" and the English "striated" = having parallel lines or grooves on the surface. In 1876 David Ferrier contributed decades of research to the subject; concluding that the corpus striatum was vital in the "organization and generation of voluntary movement". In 1941, Cécile and Oskar Vogt
Oskar Vogt (6 April 1870, in Husum – 30 July 1959, in Freiburg im Breisgau) was a German physician and neurologist. He and his wife Cécile Vogt-Mugnier are known for their extensive cytoarchetectonic studies on the brain.
Personal life
He w ...
simplified the nomenclature by proposing the term ''striatum'' for all elements in the basal ganglia
The basal ganglia (BG), or basal nuclei, are a group of subcortical nuclei, of varied origin, in the brains of vertebrates. In humans, and some primates, there are some differences, mainly in the division of the globus pallidus into an exter ...
built with striatal elements: the caudate nucleus
The caudate nucleus is one of the structures that make up the corpus striatum, which is a component of the basal ganglia in the human brain. While the caudate nucleus has long been associated with motor processes due to its role in Parkinson's d ...
, the putamen
The putamen (; from Latin, meaning "nutshell") is a round structure located at the base of the forebrain (telencephalon). The putamen and caudate nucleus together form the dorsal striatum. It is also one of the structures that compose the basal ...
, and the fundus striati, which is the ventral part linking the two preceding together ventrally to the inferior part of the internal capsule.
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. The term is still used by some sources, including Medical Subject Headings.
Other animals
In birds the term used was the ''paleostriatum augmentatum'', and in the new avian terminology listing (as of 2002) for ''neostriatum'' this has been changed to the '' nidopallium''.
In non-primate species, the islands of Calleja are included in the ventral striatum.
See also
* Cortico-basal ganglia-thalamo-cortical loop
The cortico-basal ganglia-thalamo-cortical loop (CBGTC loop) is a system of neural circuits in the brain. The loop involves connections between the cortex, the basal ganglia, the thalamus, and back to the cortex. It is of particular relevance t ...
* List of regions in the human brain
* Striatopallidal fibres
The striatopallidal fibres, also Wilson's pencils, pencil fibres of Wilson, and pencils of Wilson, are prominent myelinated fibres that connect the striatum to the globus pallidus.
Their distinctive appearance allows the putamen to be identified o ...
Additional images
File:Striatum coronal sections.gif, Striatum highlighted in green on coronal T1 MRI images
File:Striatum sagittal sections.gif, Striatum highlighted in green on sagittal T1 MRI images
File:Striatum transversal sections.gif, Striatum highlighted in green on transversal T1 MRI images
References
External links
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* https://web.archive.org/web/20131029195257/http://www.nimh.nih.gov/images/news-items/r1_braindorsal1.jpg
* https://web.archive.org/web/20090914200329/http://www.hnl.bcm.tmc.edu/fmri.html
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Cerebrum
Basal ganglia
Addiction