Basal ganglia and motor disorders Flashcards
What is the input and output of the basal ganglia?
receives cortical input
provides negative feedback to the cortex to modulate movement
consist
striatum: what is it?
functional unit: caudate and putamen. this is basically the sensory part of the BG, along with the subthalamic nucleus
Lentiform nucleus
globus pallidus and putamen: anatomical unit
What structures make up the basal ganglia?
caudate, putamen, globus pallidus, substantia nigra, and subthalamus
Where is the CAG repeat of Huntington disease? What are the symptoms?
choreiform movements, aggression, depression, and dementia
Chemical changes for huntington disease? What structures are affected?
decreased GABA and ACh in the brain
neuronal death via NMDA-R (glutamate receptor) binding and glutamate toxicity.
causes atrophy of the caudate nucleus
What is athetosis and where is the lesion?
slow writhing movements, esp. as seen in the fingers
lesion in the basal ganglia
What are common causes of myoclonus?
renal or liver failure
myoclonus is a sudden, brief, uncontrolled muscle contraction
What are causes and treatments for essential tremor?
usually genetics
patients often use alcohol to self-medicate
this decreases tremor amplitude
we give beta blockers or primidone
(remember that essential tremor worsens with holding a posture or limb position)
What is an intention tremor?
slow, zigzag motion when pointing or extending toward a target. due to cerebellar dysfunction.
Describe basal ganglia output.
output is inhibitory. neurotransmitter released is GABA.
What is the sensory part of the basal ganglia?
striatum (caudate, putamen, (nucleus accumbens)), and the subthalamic nucleus
What are the primary output parts of the basal ganglia? Where do these outputs go?
globus pallidus internal and the substantia nigra pars reticulata
go to the thalamus (to the cortex), and to the brainstem
What are the inputs to the basal ganglia? What are the neurotransmitters and what are their effects.
striatum gets excitatory (glutamate) input from the cerebral cortex
also gets input from the substantia nigra compacta (dopamine)
DA can have one of 2 effects: Stimuated D1 receptors work on the excitatory pathway.
D2 receptors trigger the inhibitory pathway
pg 453
What is the direct pathway in the basal ganglia?
DA stimulates D1 receptors in the striatum.
This stimulates these cells to release GABA. GABA acts on the globus pallidus interna and inhibits it. When the globus pallidus interna is inhibited, it can’t inhibit the thalamus. This results in INCREASED motion.
