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The putamen (/ p j u ˈ t eɪ m ə n /; from Latin, meaning "nutshell") is a subcortical nucleus with a rounded structure, in the basal ganglia nuclear group. It is located at the base of the forebrain and above the midbrain. The putamen and caudate nucleus together form the dorsal striatum.
The basal ganglia (BG) or basal nuclei are a group of subcortical nuclei found in the brains of vertebrates. In humans and other primates , differences exist, primarily in the division of the globus pallidus into external and internal regions, and in the division of the striatum .
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 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.
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 subthalamic nucleus is located ventral to the thalamus.
The indirect pathway, sometimes known as the indirect pathway of movement, is a neuronal circuit through the basal ganglia and several associated nuclei within the central nervous system (CNS) which helps to prevent unwanted muscle contractions from competing with voluntary movements. [1] It operates in conjunction with the direct pathway.
The striatum (pl.: striata) or corpus striatum [5] is a cluster of interconnected nuclei that make up the largest structure of the subcortical basal ganglia. [6] The striatum is a critical component of the motor and reward systems; receives glutamatergic and dopaminergic inputs from different sources; and serves as the primary input to the rest of the basal ganglia.
The output neurons of the nucleus accumbens send axonal projections to the basal ganglia and the ventral analog of the globus pallidus, known as the ventral pallidum (VP). ). The VP, in turn, projects to the medial dorsal nucleus of the dorsal thalamus, which projects to the prefrontal cortex as well as back to the ventral and to dorsal stri