Basal Ganglia Flashcards
What are the 4 main structures of the basal ganglia?
- Striatum
- Lentiform nucleus
- Substantia nigra
- Subthalamic nuclei
What is the striatum comprised of (2 tings)?
Caudate nucleus and putamen
What is the lentiform nucleus comprised of? (3 tings)
- Putamen
- Globus pallidus internal segment
- Globus pallidus external segment
T or F…
The substantia nigra pars reticulata produces dopamine?
FALSE
the substantia nigra pars compacta holds the dopamine producing neurons
What are the 3 thalamus relay nuclei?
- Ventral lateral nucleus (VL) motor
- Ventral anterior nucleus (VA) motor
- Mediodorsal nucleus
What are the input nuclei in the basal ganglia?
Caudate and putamen
What are the output nuclei for the basal ganglia?
Globus pallidus internal segment (GPi) = motor ctrl of body
Substantia nigra pars reticulata (SNr) = motor ctrl of head and neck
T or F…
The direct pathway of the basal ganglia inhibits unwanted movement?
FALSE!!!
the indirect pathway inhibits unwanted movement while the direct pathway allows wanted movement to occur
In the indirect pathway, what neurotransmitter does the striatum release? What charge?
GABA + enkephalin, both inhibitory
In both the direct and indirect pathways, what neurotransmitter is released by the cortex?
Glutamate, excitatory
In both the direct and indirect pathways, what neurotransmitter is released by the GPi and SNr?
GABA, Inhibitory
In both the indirect pathway, what neurotransmitter is released by the GPe?
GABA, inhibitory
In both the direct and indirect pathways, what neurotransmitter is released by the subthalamic nuclei?
Glutamate, excitatory
What pathway is in charge of allowing voluntary movement to occur?
Direct or indirect??
Direct pathway! dummy
When dopamine binds to a D1 receptor in direct pathway… is it excitatory or inhibitory?
dopamine binding to a D1 receptor in the direct pathway will be EXCITATORY. this will result in the increase in voluntary movement
“Dopamine is Excited to go directly to D1”
When dopamine binds to a D2 receptor in indirect pathway… is it excitatory or inhibitory?
dopamine binding to a D2 receptor in indirect pathway is INHIBITORY.
“dopamine is NOT excited to go indirectly to D2”
T or F…
Dopamine in the indirect pathway results in less unwanted movement?
FALSE!!
Dopamine will always promote more movement, both voluntary movement (via direct pathway) and involuntary movement (via indirect pathway).
What is an example of a hypokinetic movement disorder?
parkinson disease + late stage huntington’s disease
What is an example of a hyperkinetic movement disorder?
early stage huntington’s disease
briefly explain what bradykinesia is…
bradykinesia = slow movement
What it mean when they say rigidity is not typically velocity or directionally dependent??
This means that with rigidity.. you will feel the resistance in BOTH directions (concentric and eccentric) and it doesn’t matter how quickly you move the pt, the rigidity will stay constant
Whats dystonia?
co-contraction of agonist and antagonist mm. usually a slower sustained contraction that results in abnormal persistent posturing
What are the 2 types of rigidity and explain them?
• Two common types:
• Lead pipe rigidity: continuous resistance though range
• Cogwheel rigidity: ratchet-like interruptions in tone felt throughout range
What are the 3 types of tremors?
- Resting tremor
- Postural tremor
- Intention tremor
What’s chorea?
Nearly continuous involuntary movements of extremities, trunk,
neck, face and respiratory muscles
• Low amplitude - may conceal with voluntary movement
• Large amplitude – may disrupt voluntary movements
What’s athetosis?
Writhing, twisting movements of the limbs, face and trunk
Whats a resting tremor?
common in parkinson’s, most prominent when limbs are relaxed
Whats a postural tremor?
seen when holding limbs active but still
whats an intention tremor?
occurs when pt attempts to move limb to target
Explain parkinson’s disease…
idiopathic neurodegenerative disorder where dopamine neurons in substantia nigra pars compacta are dmg.
treated with levodopa
hypokinetic disorder
List some of the sx’s that propose a diff dx to Parkinsonism
- symmetrical distribution
- rapidly progressing
- no response to dopamine
^if any of these present then it prolly not parkinson’s
Is Huntington’s Disease Autosomal dominant or recessive?
issa autosomal dominant neurodegenerative condition
What are common sx’s of parkinsons?
resting tremor
bradykinesia
rigidity
festinating gait
Explain huntingtons disease, what anatomical structures are implicated?
huntingtons disease is the progressive atrophy/loss of the striatum
what are the clinical sx’s of Huntington’s disease?
choreatic movement disorder
abnormal eye movements
dementia
psychiatric and emotional distrubances
Compare the early to late stages of Huntingtons
early stage= degen of enkaphalin containing striatal neurons
Late stage= degen of all striatal neurons
Why is the early stage of Huntington’s hyperkinetic??
early stage involves degen of enkephalin containing striatal neurons. These are only in the indirect pathway.
By not releasing enkephalin… there is less inhibition being sent to the thalamus. Therefore… more unwanted movement occurs, hence why early-stage huntingtons is classified as a hyperkinetic disorder
Why is the late stage of Huntington’s hypokinetic??
The late stage involves the degen of all striatal neurons. This influences the direct and indirect pathways. With less inhibiton being sent from the striatum to the GPi… the GPi and SNr are able to send MORE inhibitory signals to the thalamus.
Therefore resulting in less voluntary movement, hence a hypokinetic disorder
T or F…
Deep brain stimulation is a great treatment for hyperkinetic movement disorders.
FALSE!!
deep brain stimulation is for HYPOkinetic disorders (ex-Parkinsons) that allows more voluntary movement.
