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BASAL NUCLEI (Basal Ganglia).

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Presentation on theme: "BASAL NUCLEI (Basal Ganglia)."— Presentation transcript:

1 BASAL NUCLEI (Basal Ganglia)

2 Basal Nuclei Components
Substantia nigra (within the midbrain) Subthalamic nuclei (diencephalon) Corpus striatum Red nucleus (?) Claustrum (?) Nucleus accumbens (?)

3 Corpus Striatum Composed of caudate nucleus + lentiform nucleus:
Striatum = caudate nucleus + putamen. Pallidum = globus pallidus. Putamen + globus pallidus = lentiform nucleus. Controls large subconscious movements of the skeletal muscles. The globus pallidus regulates muscle tone.

4 Corpus Striatum

5 Substantia Nigra Subdivisions
Dorsal pars compacta: Has melanin containing neurons and dopaminergic neurons. Ventral pars reticularis: Has iron-containing glial cells. Has serotonin and GABA (no melanin).

6 Substantial Nigra

7 Input Nuclei Striatum Receive widespread input from: Caudate nucleus
Putamen Nucleus accumbens Receive widespread input from: Neocortex Intralaminar nuclei Substantia nigra Dorsal raphe nucleus

8 Input Nuclei Striatum projects to:
Globus pallidus Substantia nigra Pars reticularis Via gabaminergic fibers Motor and sensory cortices project to putamen. Association areas of all lobes project to caudate nucleus.

9 Output Nuclei Globus pallidus (medial part) Substantia nigra:
Pars reticularis Ventral pallidum Fibers project to: VA/VL nuclei Mostly inhibitory

10 General Core Circuit Cerebral cortex to: Striatum to:
Globus pallidus to: Thalamus to: Portions of motor cortex to: Upper motor neurons

11 Basal Ganglia Connections Red = excitatory; Black = Inhibitory
Motor areas of cerebral cortex Ventrolateral thalamus Putamen Globus pallidus externus Output nuclei Subthalamic nuclei Pedunculo- Pontine nuclei Lateral Activation pathways Reticulospinal and Vestibulospinal pathways Substantia nigra compacta

12 Thalamic Fasciculi Ansa lenticularis:
Consists of fibers from dorsal portion of globus pallidus. Loops under internal capsule. To VA/VL complex.

13 Thalamic Fasciculi Lenticular fasciculus:
Consists of fibers from ventral portion of globus pallidus. Passes across the internal capsule. To VA/VL complex.

14 Functions Basal nuclei set organism’s level of responsiveness to stimuli. Extrapyramidal disorders are associated with basal nuclei pathology: Negative symptoms of underresponsiveness: Akinesias i.e. Parkinson disease Positive symptoms of over-responsiveness: Choreas, athetoses, ballisms i.e. Huntington’s chorea

15 Dopamine Neuronal System
Consists of nigrostriatal fibers From pars compacta of substantia nigra To striatum Dopaminergic

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