6.5a Basal Ganglia
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Transcript of 6.5a Basal Ganglia
LEARNING OBJECTIVESAt the end of the lecture, the learners
should be able to explain the manifestations of patients with movement disorders affecting the basal ganglia based on:
a.Structure/s involvedb.Pathway/s involved (direct and indirect)c.Neurotransmitter/s involved
Basal Ganglia & Cerebellum
Thalamus
Cerebral Cortex
Corticobulbar tract Corticospinal tract
LMNEx. Hypoglossal n.
LMNEx. Brachial Plexus
EPS
PYRAMIDAL
Basal Ganglia/Nuclei: Composition
Caudate nucleusPutamenGlobus pallidus
- externa
- internaSubstantia nigraSubthalamic nucleusAmygdala(?)
Substantia Substantia NigraNigra
PARTS: PARTS: 1. Pars compacta ( SNc ) 2. Pars reticulata ( SNr )- neurons are dopaminergic - inhibitory ( D2) & excitatory ( D1)-concerned with muscle
tone
1. posture 2. automatic movements as swinging of arms 3. skilled volitional movements of the trunk & limbs and 4. in cognition
Movements influenced by the basal ganglia :\
Synthesis…Questions1. Inhibition of the globus pallidus internus will
decrease the activity of the thamus. (True or False)
2. The subthamic nucleus is excitatory to _______ nuclei.
3. In the indirect pathway, increasing the inhibition of the globus pallidus externus to the next nucleus will excite the thalamus.(True or False)
General PrincipleBG acts by default to inhibit all upper motor
systemIt selects particular actions by releasingdistinct parts of upper motor system from
inhibition = disinhibitionBG controls upper motor system through
disinhibition
PRINCIPLES in PRINCIPLES in BASAL NUCLEI BASAL NUCLEI FUNCTIONSFUNCTIONS
BG / BN affects “final common path”/ LMN INDIRECTLY.
BG / BN effects are CONTRALATERAL to the side of the lesion
Strength persists in muscles but there is emergence of INVOLUNTARY MOVEMENT.
Lesions of the basal ganglia :Lesions of the basal ganglia : PARKINSON’S DIS PARKINSON’S DIS
Lewy bodies – inclusion bodies
LEWY BODIES