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 Nucleus (neuroanatomy), nuclei found in the brains of vertebrates. In humans and other primates, differences exist, primarily in the division of the globus pallidus into externa ...

. They provide connectivity between the

internal globus pallidus The internal globus pallidus (GPi or medial globus pallidus) is one of the two subcortical nuclei that provides inhibitory output in the basal ganglia, the other being the substantia nigra pars reticulata. Together with the external globus pallid ...

(GPi) and the

thalamus The thalamus (: thalami; from Greek language, Greek Wikt:θάλαμος, θάλαμος, "chamber") is a large mass of gray matter on the lateral wall of the third ventricle forming the wikt:dorsal, dorsal part of the diencephalon (a division of ...

, primarily the

ventral anterior nucleus The ventral anterior nucleus (VA) is a nucleus in the ventral nuclear group 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 ...

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 fas ...

Anatomy

They are composed of 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 thal ...

, the lenticular fasciculus ( field H₂ of Forel), and the

thalamic fasciculus The thalamic fasciculus is a component of the subthalamus (ventral thalamus). It is synonymous with field H1 of Forel. Fibers from the lenticular fasciculus ( field H2 of Forel), are joined by fibers from the ansa lenticularis – different parts ...

( field H₁ of Forel). * The ansa lenticularis is composed of fibers that pass from the ventral aspect of the

globus pallidus The globus pallidus (GP), also known as paleostriatum or dorsal pallidum, is a major component of the Cerebral cortex, subcortical basal ganglia in the brain. It consists of two adjacent segments, one external (or lateral), known in rodents simpl ...

and sweep around the posterior limb of the

internal capsule The internal capsule is a paired white matter structure, as a two-way nerve tract, tract, carrying afferent nerve fiber, ascending and efferent nerve fiber, descending axon, fibers, to and from the cerebral cortex. The internal capsule is situate ...

. They connect with the fibers of the lenticular fasciculus in the field H of Forel to form the

. * The lenticular fasciculus is composed of fibers that pass from the internal part of the

, ''through'' the posterior limb of the

, around the

zona incerta The zona incerta (ZI) is a horizontally elongated small Nucleus (neuroanatomy), nucleus that separates the larger subthalamic nucleus from the thalamus. Its connections project extensively over the brain from the cerebral cortex down into the spin ...

. 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

and

. Some fibers travel to the interthalamic nuclei.

References

{{DEFAULTSORT:Pallidothalamic Connections Thalamic connections Brainstem Basal ganglia connections

Anatomy

See also

References