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Flashcards in Basal Ganglia Deck (54)
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1
Q

What are the basal nuclei?

A
  1. Caudate nucleus
  2. Putamen
  3. Globus pallidus
  4. Subthalamic nucleus
  5. Substantia nigra
2
Q

What are the two parts of the substantia nigra?

A

Pars reticularis

Pars compacta

3
Q

Putamen + caudate nucleus = ?

A

Striatum

4
Q

Review Spoctor’s basal ganglia lecture

A
5
Q

Main afferents to the basal ganglia are to where?

A

The striatum

6
Q

Main efferents from the basal ganglia are from where?

A

Globus pallidus

Substantia nigra

7
Q

What is the function of the VA/VL complex in the thalamus on the frontal cortex?

A

Stimulates it

8
Q

What is the function of the basal ganglia on the thalamus?

A

Inhibitory

9
Q

What are the four major loops of the basal ganglia?

A
  • motor loop
  • oculomotor loop
  • Prefrontal
  • Limbic
10
Q

What is the pathway of the basal ganglia innervation?

A
cortex
Striatum
Pallidum
Thalamus
AND BACK TO CORTEX!
11
Q

True or false: The basal ganglia does not get input from the spinal cord directly.

A

True

12
Q

What is the direct path through the basal ganglia?

A

Striatum to the GP/SN

13
Q

What does the globus pallidus do to the thalamus?

A

Tonically inhibits it

14
Q

Where does the substantia nigra fit into the basal ganglia motor loops?

A

Stimulates the caudate/putamen

15
Q

What is the effect of the cortex on the striatum? What does the striatum do?

A

Cortex will stimulate the putamen, which inhibits the pallidum, which inhibits the excitatory thalamus

16
Q

What is the indirect pathway through the basal ganglia?

A

GP to subthalamic nucleus, or to GP/SN

STN to GP/SNr

17
Q

What neurotransmitter does the cerebral cortex release that has an effect on the striatum?

A

Glutamate (excitatory)

18
Q

What neurotransmitter does the striatum release that has an effect on the globus pallidus?

A

GABA (inhibitory) and something else

19
Q

What are the two parts of the BG loops that release E?

A

Cortex

Subthalamic nucleus

20
Q

What neurotransmitter do most parts of the BG release, except for the cortex and subthalamic nucleus?

A

GABA

21
Q

Where does the body movement loop start in the cortex? (3)

A

Primary motor, premotor and supplementary motor

22
Q

How can the body movement loop be specific?

A

might selectively activate some movements and suppress others

23
Q

What part of the cortex does the oculomotor loop start in?

A

FEF and supplementary eye field

24
Q

What is the function of the oculomotor loop?

A

Involved in the control of saccadic eye movements

25
Q

Where does the prefrontal loop start in the cortex?

A

Dorsolateral prefrontal cortex

26
Q

What is the function of the prefrontal cortex?

A

regulate the initiation and termination of cognitive processes such as planning, attention and working memory

27
Q

What part of the cortex does the limbic loop start in?

A

Anterior cingulate gyrus

Ventral striatum

28
Q

What is the function of the limbic loop?

A

regulate emotional behavior and motivation

29
Q

What are the symptoms of parkinsonism? (3)

A
  • Rhythmic tremor at rest
  • Bradykinesia (or akinesia)
  • Postural flexion and instability
30
Q

What is the incidence of parkinson’s disease in patients over the age of 60?

A

1-2%

31
Q

When does parkinson’s usually appear?

A

between 55-65

32
Q

What is the gait like in parkinson’s?

A

Small, shuffling steps and the absence of arm swing that normally accompanies or walking

33
Q

What is the handwriting like in parkinson’s?

A

(micrographia)

34
Q

What is the frozen gait syndrome seen in Parkinson’s?

A

Sudden inability to start walking

35
Q

What is the pathophysiology of Parkinson’s?

A

Degeneration of dopaminergic projection to striatum from the substantia nigra

36
Q

What is the protein that is accumulated in Parkinson’s?

A

alpha-synuclein

37
Q

What are the facies seen in parkinson’s?

A

Mask like (cannot initiate movements)

38
Q

What are the cells that are lost in Parkinson’s? How many do you have to lose to show symptoms?

A

Pars compacta

80%

39
Q

What is the effect on the basal ganglia circuitry when the substantia nigra is removed?

A

Increased inhibition to the globus pallidus, leading to less inhibition of the subthalamic nucleus

More tonic inhibition of the thalamus

40
Q

What are the two pharmacologic treatments for parkinson’s?

A

L-dopa

Acetylcholine agonists

41
Q

What is the MOA of deep brain stimulation for Parkinson’s?

A

Stimulate the dopaminergic neurons

42
Q

What are the symptoms of Huntington’s?

A

Chorea
Dementia
Bradykinesia

43
Q

What is the pathophysiology of Huntington’s? (3)

A

a. First selective loss of GABA/enkephalin projection from striatum to GPe
b. Later more widespread degeneration of striatal neurons
c. Also loss of cortical neurons

44
Q

What is the genetic basis for Huntington’s disease? How is it inherited?

A

Triplet CAG repeat in Huntingtin gene.

Inherited in an AD fashion

45
Q

After how many CAG repeats does Huntington’s become symptomatic? What is the relationship between age of onset, and number of repeats?

A

40 or more

More = earlier onset

46
Q

What is hemiballismus?

A

involuntary, violent, flinging movements of a limb while the patient is awake

47
Q

What is tardive dyskinesia?

A

iatrogenic disorder due to long-term treatment with drugs that affect dopamine systems

48
Q

What is athetosis?

A

Slow, writhing movements

49
Q

What are chorea?

A

brief, sudden, random, twitch-like movements of limbs or facial muscles. They resemble fragments of normal voluntary movement.

50
Q

What is the effect on the basal ganglia in Huntingtons?

A

Loss of striatum inhibition to the external segment of the globus pallidus,

Thus increased inhibition of the internal segment of the GP, resulting in greater inhibition of the thalamus

51
Q

Draw out the basal ganglia pathway.

A
52
Q

Hemiballismus is often associated with a lesion where?

A

Contralateral Subthalamus

53
Q

What is the pathophysiology of Tardive dyskinesia?

A

Antipsychotic drugs cause denervation hypersensitivity since they block dopamine receptors

54
Q

What are the symptoms of tardive dyskinesia?

A

Repetitive, stereotypic movements (continual chewing)