Basal ganglia of endbrain and movement

Basal ganglia are located in the basis of a endbrain and represent the important subcrustal connecting link between associative areas of a cerebral cortex and impellent areas of a cerebral cortex. Following structures are concern to basal ganglia: a striped kernel of basal ganglia consisting caudate nucleus of basal ganglia and shells of basal ganglia, a pale sphere of basal ganglia subdivided on internal and external departments, a black substance of basal ganglia and a subthalamic kernel of basal ganglia. In structure of basal ganglia often include also a fencing and less often - amygdala.

Infringements of movements are caused by defeat of basal kernels - the anatomically isolated group of pair subcrustal structures.

Basal kernels facilitate movements started by a bark and suppress extra accompanying movements. Striatum receives the somatotopic organized projections almost from all zones of a bark. These projections are organized in the form of parallel ways which begin from frontal areas, postcentral (somatotopic) areas, precentral (motor) areas and parietotemporal-occipital areas.

Neurocytes of striatum send fibres to the structures shaping the main axifugal way of basal kernels - to a mesh part of a black substance and a medial pale sphere.

Thus, at braking neurocytes a mesh part of a black substance and a medial pale sphere exciting influence thalamus on a bark amplifies - as promotes simplification of movement started by a bark.

On the contrary, at excitation neurocytes a mesh part of a black substance and a medial pale sphere exciting influence thalamus on a bark suppresses - that leads to braking of unnecessary movement.

On a spinal cord basal kernels have no direct output. The direct way from striatum to a mesh part of a black substance and a medial pale sphere is formed brake by fibres. Their function consists in strengthening exciting influence of kernels thalamus on those departments of a motor bark which are responsible for the necessary movement. The indirect way is organized more difficultly. Its function consists in suppression of exciting influence thalamus on other departments of a motor bark.

Thus, if activation of a direct way from striatum strengthens excitation of a motor bark activation of an indirect way - weakens.

Activity of these two ways is adjusted with the compact part of a black substance sending to striatum dopaminergic fibres. These fibres raise direct a axifugal way to striatum (through neurocytes with D1-receptors) and brake - indirect (through neurocytes with D2-receptors). Striatum sends also brake gamma-aminobutyric acid fibres to a compact part of a black substance, forming that with it a negative feedback. Finally, activity of striatum modulate it cholinergic inserted neurocytes - antagonists dopaminergic neurocytes.