Prethalamus
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The subthalamus or prethalamus is a part of the
diencephalon The diencephalon (or interbrain) is a division of the forebrain (embryonic ''prosencephalon''). It is situated between the telencephalon and the midbrain (embryonic ''mesencephalon''). The diencephalon has also been known as the 'tweenbrain in o ...
. Its most prominent structure is 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 ...
. The subthalamus connects 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 rode ...
, a basal nucleus of the
telencephalon The cerebrum, telencephalon or endbrain is the largest part of the brain containing the cerebral cortex (of the two cerebral hemispheres), as well as several subcortical structures, including the hippocampus, basal ganglia, and olfactory bulb. ...
.


Structure

The subthalamus is located
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 ...
to the
thalamus The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all direct ...
, medial to the
internal capsule The internal capsule is a white matter structure situated in the inferomedial part of each cerebral hemisphere of the brain. It carries information past the basal ganglia, separating the caudate nucleus and the thalamus from the putamen and the ...
and
lateral Lateral is a geometric term of location which may refer to: Healthcare *Lateral (anatomy), an anatomical direction * Lateral cricoarytenoid muscle * Lateral release (surgery), a surgical procedure on the side of a kneecap Phonetics *Lateral co ...
to the
hypothalamus The hypothalamus () is a part of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamus ...
. It is a region formed by several
grey matter Grey matter is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil ( dendrites and unmyelinated axons), glial cells ( astrocytes and oligodendrocytes), synapses, and capillaries. Grey matter is ...
nuclei and their associated
white matter White matter refers to areas of the central nervous system (CNS) that are mainly made up of myelinated axons, also called tracts. Long thought to be passive tissue, white matter affects learning and brain functions, modulating the distribu ...
structures, namely: *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 ...
, whose neurons contain
glutamate Glutamic acid (symbol Glu or E; the ionic form is known as glutamate) is an α-amino acid that is used by almost all living beings in the biosynthesis of proteins. It is a non-essential nutrient for humans, meaning that the human body can synt ...
and have excitatory effects over neurons of
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 rode ...
and
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 ap ...
*
Zona incerta The zona incerta (ZI) is a horizontally elongated region of gray matter in the subthalamus below the thalamus. Its connections project extensively over the brain from the cerebral cortex down into the spinal cord. Its function is unknown, though ...
, located between
fields of Forel The fields of Forel are areas in a deep part of the brain known as the diencephalon. They are below the thalamus and consist of three defined, white matter areas of the subthalamus. These three regions are also named "H fields": *Field H1, is the ...
H1 and H2. It is continuous with the
thalamic reticular nucleus The thalamic reticular nucleus is part of the ventral thalamus that forms a capsule around the thalamus laterally. However, recent evidence from mice and fish question this statement and define it as a dorsal thalamic structure. It is separated fro ...
and receives input from the precentral cortex. *
Subthalamic fasciculus The subthalamic fasciculus is a bi-directional neural tract that connects the subthalamic nucleus and the globus pallidus The globus pallidus (GP), also known as paleostriatum or dorsal pallidum, is a subcortical structure of the brain. It consi ...
, formed by fibers that connect the globus pallidus with the subthalamic nucleus *
Fields of Forel The fields of Forel are areas in a deep part of the brain known as the diencephalon. They are below the thalamus and consist of three defined, white matter areas of the subthalamus. These three regions are also named "H fields": *Field H1, is the ...
*
Ansa lenticularis The ansa lenticularis (''ansa lentiformis'' in older texts) is a part of the brain, making up the superior layer of the substantia innominata. Its fibers, derived from the medullary lamina of the lentiform nucleus, pass medially to end in the tha ...
During development the subthalamus is continuous with the
hypothalamus The hypothalamus () is a part of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamus ...
, but is separated by
white matter White matter refers to areas of the central nervous system (CNS) that are mainly made up of myelinated axons, also called tracts. Long thought to be passive tissue, white matter affects learning and brain functions, modulating the distribu ...
fibres mainly from the
internal capsule The internal capsule is a white matter structure situated in the inferomedial part of each cerebral hemisphere of the brain. It carries information past the basal ganglia, separating the caudate nucleus and the thalamus from the putamen and the ...
. Caudally, the subthalamus or prethalamus is separated from the thalamus by the
zona limitans intrathalamica The ''zona limitans intrathalamica'' (ZLI) is a lineage-restriction compartment and primary developmental boundary in the vertebrate forebrain (which is analogous to the human cerebrum) that serves as a signaling center and a restrictive border bet ...
. Postnatally, the subthalamus lies beneath the
thalamus The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all direct ...
, hence 'sub' (meaning below) 'thalamus'. It also lies dorsolateral to the
hypothalamus The hypothalamus () is a part of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamus ...
.


Connections

The subthalamus develops efferent (output) connections to the
striatum The striatum, or corpus striatum (also called the striate nucleus), is a nucleus (a cluster of neurons) in the subcortical basal ganglia of the forebrain. The striatum is a critical component of the motor and reward systems; receives gluta ...
(
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
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 ...
) in the
telencephalon The cerebrum, telencephalon or endbrain is the largest part of the brain containing the cerebral cortex (of the two cerebral hemispheres), as well as several subcortical structures, including the hippocampus, basal ganglia, and olfactory bulb. ...
, to the dorsal thalamus (medial and lateral nuclear groups) in the diencephalon, and to the
red nucleus The red nucleus or nucleus ruber is a structure in the rostral midbrain involved in motor coordination. The red nucleus is pale pink, which is believed to be due to the presence of iron in at least two different forms: hemoglobin and ferritin. ...
and
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 ap ...
in the mesencephalon. It receives afferent (input) connections from the substantia nigra and striatum.


See also

*
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 ...
*
Zona incerta The zona incerta (ZI) is a horizontally elongated region of gray matter in the subthalamus below the thalamus. Its connections project extensively over the brain from the cerebral cortex down into the spinal cord. Its function is unknown, though ...


References


External links

* https://web.archive.org/web/20080504165606/http://isc.temple.edu/neuroanatomy/lab/atlas/pdhn/ {{Authority control Basal ganglia