Basal Ganglia Flashcards
anatomical basal ganglia
caudate nucleus + lentiform nucleus + claustrum + amygdala
physiological basal ganglia
caudate nucleus + lentiform nucleus + subthalamus + substantia nigra
Neostriatum(striatum)
putamen + caudate nucleus
- input component of the basal ganglia
paleostriatum(pallidum)
globus pallidus
lentiform nucleus
globus pallidus + putamen
corpus striatum
caudate nucleus + lentiform nucleus(globus pallidus + putamen)
caudate nucleus
C-shaped(close to the lateral ventricle)
- head, body, tail
- works with putamen closely
- input nucleus of basal ganglia
putamen
input of basal ganglia
- lateral to internal capsule
globus pallidus
medial and inferior to putamen
1) internal = primary output for basal ganglia
2) external = interacts with subthalamus
pars reticulata
output for basal ganglia
pars compacta
dopamine is made and stored
direct loop of basal ganglia
cortex-(+)->striatum-(-)->globus pallidus-(-)->thalamus-(+)->cortex
- corticospinal
indirect loop of the basal ganglia
cortex-(+)->striatum-(-)->globus pallidus-(-)->subthalamus-(+)->globus pallidus-(-)->thalamus-(+)->cortex
- rubrospinal, tectospinal, reticulospinal, vestibulospinal
akinesia
unable to move
- trouble initiating movement(esp. thresholds and turns)
- motor pattern exists, but trouble initiating
- rigid trunk
- short steps with no trunk movement
Basal ganglia Direct Motor loop
CTX –> corticostriate(+) –> striatum(caudate putamen) –> striopallidal(-) –> pallidum(globus pallidus) –> thalamic fasc.(-) –> thalamus –> (+) –> CTX
Basal ganglia Indirect motor loop
CTX –> corticostriate(+) –> striatum(caudate putamen) –> striopallidal(-) –> pallico-subthalamic(-) –> subthalamus –> subthalamic fasc.(+) –> pallidum(globus pallidus) –> thalamic fasc.(-) –> thalamus –> (+) –> CTX
4 signs of parkinson’s
TRAP T = tremor(often 1st sign) R = rigidity A = akinesia(bradykinesia) P = postural disturbances
Huntington’s Chorea
autosommal recessive disease
- problem in the basal ganglia
- overactivation of putamen –> inhibits globus pallidus –> excites pedunculopontine –> involuntary movement of voluntary muscles
- show symptoms in 3rd or 4th decade of life
lesions in globus pallidus
athetosis
athetosis
slow writhing movements
lesions in the subthalamus
hemiballismus
hemiballismus
flinging of entire limb(involuntary movement)
lesions in putamen
choreiform movements
choreiform movements
brisk and purposeless movements
possible cause for Parkinson’s for younger pt’s
exposure to drugs
possible cause for Parkinson’s for older pt’s
exposure to free radicals
Parkinson’s cause
degeneration of substantia nigra and pedunculopontine
Neuro of Parkinson’s
subthalamus excites globus pallidus which inhibits pedunculopontine and the midbrain which causes rigidity(LMN’s) and decreased walking patterns
Basal ganglia connection #1
CTX –> corticostriate(+) –> striatum(caudate putamen) –> striopallidal(-) –> pallidum(globus pallidus) –> thalamic fasc.(-) –> thalamus –> (+) –> CTX
Basal ganglia connection #2
CTX –> corticostriate(+) –> striatum(caudate putamen) –> striopallidal(-) –> pallico-subthalamic(-) –> subthalamus –> subthalamic fasc.(+) –> pallidum(globus pallidus) –> thalamic fasc.(-) –> thalamus –> (+) –> CTX
4 signs of parkinson’s
TRAP T = tremor(often 1st sign) R = rigidity A = akinesia(bradykinesia) P = postural disturbances
Huntington’s Chorea
autosommal dominant disease
- problem in the basal ganglia
- overactivation of putamen –> inhibits globus pallidus –> excites pedunculopontine –> involuntary movement of voluntary muscles
- show symptoms in 3rd or 4th decade of life
lesions in globus pallidus
athetosis
athetosis
slow writhing movements
lesions in the subthalamus
hemiballismus
hemiballismus
flinging of entire limb(involuntary movement)
lesions in putamen
choreiform movements
choreiform movements
brisk and purposeless movements
possible cause for Parkinson’s for younger pt’s
exposure to drugs
possible cause for Parkinson’s for older pt’s
exposure to free radicals
Parkinson’s cause
degeneration of substantia nigra and pedunculopontine
Neuro of Parkinson’s
subthalamus excites globus pallidus which inhibits pedunculopontine and the midbrain which causes rigidity(LMN’s) and decreased walking patterns
Nuclei in the basal ganglia
caudate putamen globus pallidus subthalamic nucleus substantia nigra
output of the basal ganglia motor circuit
- regulates muscle contraction
- muscle force
- multi-joint movements
- sequencing of the movements via pathways
Basal ganglia to voluntary movement
BG -(-)–> motor thalamus -(+)–> motor cortex -(+)–> corticospinal tracts -(+)–> LMN’s -(+)–> Voluntary muscles
Basal ganglia to postural
BG -(-)–> ventrolateral Pedunculopontine nucleus(brainstem) -(-)–> reticulospinal tracts -(+)–> LMN’s -(+)–> Postural and girdle muscles
Basal ganglia walking
BG -(-)–> midbrain locomotor region -(+)–> reticulospinal tracts -(+)–> stepping pattern generators -(+)–> LMN’s -(+)–> walking
globus pallidus
output of the basal ganglia motor circuit
- inhibits motor thalamus, PPN, and midbrain locomotor region
subthalamic nucleus
processes information within the basal ganglia circuit
putamen
receives input from premotor and motor cortex
motor loop
1) cortex = motor and premotor cortex
2) BG = putamen and globus pallidus
3) thalamus = ventral lateral
executive loop
1) cortex = dorsolateral prefrontal cortex
2) BG = caudate and globus pallidus
3) thalamus = ventral anterior
behavior flexibility and control loop
1) cortex = ventrolateral prefrontal and lateral orbital cortex
2) BG = caudate and substantia nigra reticularis
3) thalamus = mediodorsal
limbic loop
1) cortex = medial orbital and medial prefrontal cortex
2) BG = striatum and pallidum
3) thalamus = mediodorsal
affects of direct circuit(loop)
too little excitation = bradykinesia
too much excitation = tremors and rigidity
- opposite of indirect
affects of indirect pathway
overexcitation = bradykinesia
too little excitation = tremors and rigidity
- opposite direct
pathways to direct circuit
corticospinal tract
pathways to indirect circuit
rubrospinal, tectospinal, reticulospinal(2), vestibulospinal(2)
