The pallidothalamic tracts (or pallidothalamic connections)
are a part 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 ...
. They provide connectivity between the
internal globus pallidus
The internal globus pallidus (GPi or medial globus pallidus; in rodents its homologue is known as the entopeduncular nucleus) and the external globus pallidus (GPe) make up the globus pallidus. The GPi is one of the output nuclei of the basal gang ...
(GPi) and 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 directions, ...
, primarily the
ventral anterior nucleus
The ventral anterior nucleus (VA) is a nucleus of the thalamus. It acts with the anterior part of the ventral lateral nucleus to modify signals from the basal ganglia.
Inputs and outputs
The ventral anterior nucleus receives neuronal inputs from t ...
and the
ventral lateral nucleus
The ventral lateral nucleus (VL) is a nucleus in the ventral nuclear group of the thalamus.
Inputs and outputs
It receives neuronal inputs from the basal ganglia which includes the substantia nigra and the globus pallidus (via the thalamic fasc ...
.
Anatomy
They are composed of the
ansa lenticularis, the
lenticular fasciculus
The lenticular fasciculus is a tract connecting the globus pallidus (internus) to the thalamus and is a part of the thalamic fasciculus. It is synonymous with field H2 of Forel. The thalamic fasciculus (composed of both the lenticular fasciculus a ...
(
field H2 of Forel), and the
thalamic fasciculus
The thalamic fasciculus is a component of the subthalamus. It is synonymous with field H1 of Forel. Nerve fibres form a tract containing cerebellothalamic (crossed) and pallidothalamic (uncrossed) fibres, that is insinuated between the thalamus ...
(
field H1 of Forel).
* The ansa lenticularis is composed of fibers that pass from the ventral aspect of the
globus pallidus and sweep around the posterior limb of 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 ...
. They connect with the fibers of the lenticular fasciculus in the
field H of Forel to form the
thalamic fasciculus
The thalamic fasciculus is a component of the subthalamus. It is synonymous with field H1 of Forel. Nerve fibres form a tract containing cerebellothalamic (crossed) and pallidothalamic (uncrossed) fibres, that is insinuated between the thalamus ...
.
* The lenticular fascicles is composed of fibers that pass from the internal part of the
globus pallidus, ''through'' the posterior limb of 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 ...
, around 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 ...
. These fibers connect with the fibers of the ansa lenticularis in the field H of Forel to form the thalamic fasciculus.
* The thalamic fasciculus is formed by the fibers of the ansa lenticularis and the lenticular fasciculus that merge in the field H of Forel. The fibers of this fasciculus then travel to the thalamus and primarily terminate in the
ventral anterior nucleus
The ventral anterior nucleus (VA) is a nucleus of the thalamus. It acts with the anterior part of the ventral lateral nucleus to modify signals from the basal ganglia.
Inputs and outputs
The ventral anterior nucleus receives neuronal inputs from t ...
and
ventral lateral nucleus
The ventral lateral nucleus (VL) is a nucleus in the ventral nuclear group of the thalamus.
Inputs and outputs
It receives neuronal inputs from the basal ganglia which includes the substantia nigra and the globus pallidus (via the thalamic fasc ...
.
Some fibers travel to the interthalamic nuclei.
See also
*
Primate basal ganglia system
References
{{DEFAULTSORT:Pallidothalamic Connections
Thalamic connections
Brainstem
Basal ganglia connections