Transcript BASAL NUCLEI - University of Kansas

BASAL NUCLEI
(Basal Ganglia)
Basal Nuclei Components
Substantia nigra (within the midbrain)
 Subthalamic nuclei (diencephalon)
 Corpus striatum
 Red nucleus (?)
 Claustrum (?)
 Nucleus accumbens (?)

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.

Corpus Striatum
Corpus Striatum
(Telencephalon)
Striatum
Caudate Nucleus
Pallidum
Putamen
Globus Pallidus
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).
Substantial Nigra
Substantia Nigra
Mesencephalon
Dorsal
Pars compacta
Ventral
Pars reticularis
Melanin containing neurons
Dopaminergic neurons
Iron-containing glial cells
Serotonin and GABA
Input Nuclei

Striatum
Caudate nucleus
Putamen
Nucleus accumbens

Receive widespread input from:
Neocortex
Intralaminar nuclei
Substantia nigra
Dorsal raphe nucleus
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.

Output Nuclei
Globus pallidus (medial part)
 Substantia nigra:

Pars reticularis
Ventral pallidum
 Fibers project to:

VA/VL nuclei
Mostly inhibitory
General Core Circuit
Cerebral cortex to:
 Striatum to:
 Globus pallidus to:
 Thalamus to:
 Portions of motor cortex to:
 Upper motor neurons

Basal Ganglia Connections
Red = excitatory; Black = Inhibitory
Motor areas of cerebral cortex
Ventrolateral
thalamus
Putamen
Globus pallidus
externus
Output
nuclei
PedunculoPontine
nuclei
Reticulospinal and
Vestibulospinal
pathways
Subthalamic
nuclei
Substantia nigra
compacta
Lateral
Activation
pathways
Thalamic Fasciculi

Ansa lenticularis:
Consists of fibers from dorsal portion of
globus pallidus.
Loops under internal capsule.
To VA/VL complex.
Thalamic Fasciculi

Lenticular fasciculus:
Consists of fibers from ventral portion of
globus pallidus.
Passes across the internal capsule.
To VA/VL complex.
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
Dopamine Neuronal System
Consists of nigrostriatal fibers
 From pars compacta of substantia nigra
 To striatum
 Dopaminergic
