The basal nuclei, also known as basal ganglia, are a group of subcortical structures in the brain primarily involved in regulating voluntary motor control, procedural learning, routine behaviors, and cognitive and emotional functions. The primary components of the basal nuclei include The Caudate nucleus is C-shaped structure regulates voluntary movement and is associated with learning and memory. It works closely with the other components of the basal nuclei to process and relay motor information. The Putamen is located next to the caudate nucleus, the putamen plays a key role in motor skills and movement regulation. It is involved in a variety of movement control processes and motor learning. The Globus Pallidus is situated medial to the putamen, the globus pallidus consists of two parts: the external segment (GPe) and the internal segment (GPi). The GPi acts as a major output nucleus, sending inhibitory signals to the thalamus, which in turn projects to the motor cortex to help regulate movement. The Subthalamic Nucleus is found below the thalamus, this nucleus modulates the output of the globus pallidus and plays a critical role in controlling movement. It connects with various parts of the basal nuclei and helps balance excitatory and inhibitory signals. The Substantia Nigra is located in the midbrain, the substantia nigra has two parts: the pars compacta (SNc) and the pars reticulata (SNr). The SNc is important for producing dopamine and regulating movement and reward. The SNr is an output nucleus projecting to the thalamus and other brain areas.
These components form intricate circuits that integrate cortical inputs and influence motor and cognitive functions by modulating thalamic activity and subsequent cortical output. Additionally, these nuclei interact with various cortical and subcortical areas, forming circuits that facilitate the initiation and smooth execution of movements, as well as the modulation of motor patterns. Dysfunctions in the basal nuclei are associated with several neurological disorders, including Parkinson’s, Huntington’s, and Tourette syndrome.