Direct pathway

The direct pathway passes through the caudate nucleus, putamen, and globus pallidus, which are parts of the basal ganglia.

[2] In a resting individual, a specific region of the globus pallidus, the internal globus pallidus (GPi), and a part of the substantia nigra, the pars reticulata (SNpr), send spontaneous inhibitory signals to the ventral lateral nucleus (VL) of the thalamus, through the release of GABA, an inhibitory neurotransmitter.

[3] Inhibition of the inhibitory neurons that project to the ventral anterior nucleus (VA), which project to the motor regions of the cerebral cortices of the telencephalon, leads to an increase in activity in the motor cortices, thereby promoting muscular action.

[4] In the direct pathway, the motor cortices send activating signals to the caudate and putamen (which together form the dorsal striatum).

Interruption or dysfunction of the direct pathway results in hypokinesia, which is, in general terms, a disease which leads to a lack of motion in our body.

Depicted are parts of the basal ganglia and their interconnections as revealed by diffusion spectrum imaging based on thirty subjects from the human connectome project (HCP MGH). Direct, indirect and hyperdirect pathways are visualized in different colors (see legend). Subcortical structures are rendered based on the Harvard-Oxford subcortical (Thalamus) as well as the Atlasing of the Basal Ganglia atlas (other structures). Rendering was generated using TrackVis software.