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The striatum includes the caudate nucleus (top), and the lentiform nucleus (the putamen (right) and the globus pallidus (lower left)) The striatum is the largest structure of the basal ganglia. The striatum is divided into two subdivisions, a ventral striatum and a dorsal striatum, based upon function and connections.
The globus pallidus (GP), also known as paleostriatum or dorsal pallidum, [1] is a major component of the subcortical basal ganglia in the brain. It consists of two adjacent segments, one external (or lateral), known in rodents simply as the globus pallidus , and one internal (or medial).
Caudate nucleus within the skull. Along with the putamen, the caudate forms the dorsal striatum, which is considered a single functional structure; anatomically, it is separated by a large white-matter tract, the internal capsule, so it is sometimes also described as two structures—the medial dorsal striatum (the caudate) and the lateral dorsal striatum (the putamen).
The substantia nigra is located in the ventral midbrain of each hemisphere. It has two distinct parts, the pars compacta (SNc) and the pars reticulata (SNr). The pars compacta contains dopaminergic neurons from the A9 cell group that forms the nigrostriatal pathway that, by supplying dopamine to the striatum, relays information to the basal ganglia.
Along with the caudate nucleus it forms the dorsal striatum. The caudate and putamen contain the same types of neurons and circuits – many neuroanatomists consider the dorsal striatum to be a single structure, divided into two parts by a large fiber tract, the internal capsule, passing through the middle.
In the direct pathway, the motor cortices send activating signals to the caudate and putamen (which together form the dorsal striatum). The cells of the direct pathway in the caudate and putamen that receive these signals are inhibitory and, once they become activated, send inhibitory signals to the GPi and SNpr and stop activity there.
The ventral striatum and dorsal striatum collectively form the striatum, which is the main component of the basal ganglia. [2] The dopaminergic neurons of the mesolimbic pathway project onto the GABAergic medium spiny neurons of the nucleus accumbens and olfactory tubercle.
The dorsal striatum is divided into the caudate and putamen by the internal capsule while the ventral striatum is composed of the nucleus accumbens and olfactory tubercle. [ 21 ] [ 22 ] The caudate has three primary regions of connectivity, with the head of the caudate demonstrating connectivity to the prefrontal cortex, cingulate cortex and ...