Synonyms
Stem ganglia, basal nuclei
Introduction
The term “basal ganglia” refers to core areas located below the cerebral cortex (subcortical), which are primarily responsible for controlling functional aspects of motor function. In addition, the basal ganglia control cognitive signals and are involved in processing information from the limbic system. From a neuroanatomical point of view, the basal ganglia form an essential part of the so-called extrapyrimidal motor system (EPMS).
Anatomy
The basal ganglia are made up of different structures within the two hemispheres of the brain which carry out a lively exchange of information. From an anatomical point of view, the basal ganglia are made up of the following parts: Nucleus caudatus (curly nucleus)
- Nucleus caudatus (curly nucleus)
- Nucleus lentiformis (lenticular nucleus) which in turn is divided into:Putamen (shell body)Pallidum (Globus pallidus)
- Putamen (shell body)
- Pallidum (Globus pallidus)
- Putamen (shell body)
- Pallidum (Globus pallidus)
Functionally, the black substance (substantia nigra) of the midbrain and the subthalamic nucleus are also counted as basal ganglia. During early embryonic development, the putamen and the caudatus nucleus are in close proximity.
However, as the central nervous system matures, these two structures are separated by the formation of long projection pathways (so-called capsula interna). In the adult brain, only a fine stripe called “striatum” connects the putamen with the curly nucleus. The striatum is also the only entry point into the basal ganglion system.
Impulses from the outside are thus passed on via the fine fiber train into the individual structures of the basal ganglia. The Basal Ganglia receive information mainly from the cerebral cortex and the grey matter. In addition, various core areas of the central nervous system (for example, the so-called raphe nuclei and the reticular formatio) also regularly send impulses into the basal ganglia. Outgoing information is sent from the basal ganglia via the pallidum internum (GPI) to other brain regions. Via the inhibitory neurotransmitter GABA, the basal ganglia project directly onto the thalamus.
Function
Overall, the human brain has so far been considered less well understood. For this reason, the complex functions of the basal ganglia have been little researched to date. It is assumed that the individual structures of the basal ganglia play a decisive role in the selection and processing of motor and non-motor action patterns.
In addition, they regulate the suppression of activation patterns that are currently not needed. In the course of these complex tasks, however, the Basal Ganglia do not work independently. Rather, the caudatus nucleus, the putamen and the globus pallidus are integrated into a control loop as filter stations.
The flow of information emanates from the cerebral cortex, is transmitted via the basal ganglia to the thalamus and from there to the frontal lobe of the cerebral cortex. Almost every part of the cerebral cortex sends information to the entry station of the basal ganglia (i.e. the striatum). The only exceptions are the primarily visual cortex (visual centre) and the areas of the brain responsible for hearing. Via the exit stations of the basal ganglia (substantia nigra and globus pallidus), the final information processed in nuclei is sent to the thalamus via inhibitory impulses. The thalamus in turn sends activating impulses to the cerebral cortex of the frontal lobe.
