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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.
The direct pathway, sometimes known as the direct pathway of movement, is a neural pathway within the central nervous system (CNS) through the basal ganglia which facilitates the initiation and execution of voluntary movement. [1] It works in conjunction with the indirect pathway.
English: Circuits of the basal ganglia. Picture shows 2 coronal slices that have been superimposed to include the involved basal ganglia structures. + and - signs at the point of the arrows indicate respectively whether the pathway is excitatory or inhibitory in effect.
English: Connection diagram of the basal ganglia. Glutamatergic pathways are red, dopaminergic pathways are magenta and GABAergic pathways are blue. GPe = Globus Pallidus external; GPi = Globus Pallidus internal; STN = SubThalamic Nucleus; SNpr = Pars Reticulata portion of Substantia Nigra; SNpc = Pars Compacta portion of Substantia Nigra
Anatomical overview of the main circuits of the basal ganglia. Subthalamic nucleus is shown in red. Picture shows 2 coronal slices that have been superimposed to include the involved basal ganglia structures. + and - signs at the point of the arrows indicate respectively whether the pathway is excitatory or inhibitory in effect.
As the GPi is one of the direct output centers of the basal ganglia, this causes disinhibition of the thalamus, increasing overall ease of initiating and maintaining movement. As this pathway only contains one synapse (from the striatum to the internal globus pallidus), it is known as the direct pathway. [4]
Another model proposes the basal ganglia acts as a selection mechanism, where actions are generated in the cortex and are selected based on context by the basal ganglia. [13] The CBGTC loop is also involved in reward discounting, with firing increasing with an unexpected or greater than expected reward. [ 2 ]
Dopaminergic pathways (dopamine pathways, dopaminergic projections) in the human brain are involved in both physiological and behavioral processes including movement, cognition, executive functions, reward, motivation, and neuroendocrine control. [1] Each pathway is a set of projection neurons, consisting of individual dopaminergic neurons.