Basal Ganglia Flashcards

1
Q

What is the function of the basal ganglia?

A

Important in voluntary movements, adjusting posture

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2
Q

What makes up the striatum?

Which are motor and which are cognitive?

A

Putamen -motor

Caudate - cognitive

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3
Q

What makes up the lentiform nucleus?

A

Putamen - motor

Globus pallidus

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4
Q

What is another name for the substantia innominata?

A

Substantia nigra

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5
Q

What are the two parts of the substantia nigra?

A

Pars reticulata

Pars compacta

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6
Q

For the basal ganglia, which pathway is excitatory and which pathway is inhibitory?

And what receptors do they have?

A

Direct = D1 receptor = excitatory

Indirect = D2 receptor = inhibitory

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7
Q

If dopamine acts thru D1, what is the effect?

A

Excitatory pathway is stimulated

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8
Q

If dopamine acts thru D2, what is the effect?

A

Inhibitory pathway is inhibited

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9
Q

How does the direct/excitatory pathway of basal ganglia work?

A

SNc input —> striatum, releases GABA

GABA —> inhibits GPi

GPi cant inhibit thalamus

=increased motion

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10
Q

How does the indirect/inhibitory pathway work?

A

SNc —> striatum, releases GABA

GABA—> inhibits GPe —> activates Sub-thalamic nucleus (STN)

STN —> stimulates GPi —> GABA released and goes to thalamus

=inhibits thalamus, decreased motion

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11
Q

What is the blood supply for the basal nuclei?

A

primary from MCA - lenticulostriate As.

Also ACA and Anterior choroidal

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12
Q

What is the classic triad associated with Parkinson’s disease?

A

Tremor- pill rolling
Cogwheel Rigidity
Bradykinesia

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13
Q

What are symptoms of Parkinson’s disease?

A

Classic triad

Hypokinesia
Postural instability
Dementia
Visuoperceptive impairments 
Can affect walking (sloooow walking)
Speech affected and facial expressions
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14
Q

What is the underlying cause of Parkinson’s?

A

No dopamine via Pars Compacta** of substantia nigra

No dopamine = striatum not stimulated = no GABA released to act on Pars reticulata and GPi = thalamus still inhibited

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15
Q

What are some cause so f Parkinsonian Syndyrome?

A
Idiopathic Parkinson’s disease
Encephalitis lethargically
Head trauma
			• Dementia pugilistica
MPTP 
			• Designer drug
CO and Manganese poisoning
Drug induced
			• Neuroleptic (dopamine blocking drugs) 
Wilson Diseae
			• Heptolenticular degeneration 
Rigidity 
• + other deficits in multiple neurodegenerative diseases
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16
Q

What are some treatments for Parkinson’s?

A

Drugs that increase dopamine or prevent its breakdown

Deep brain stimulation

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17
Q

What defect does Huntington’s Chorea result from?

A

Degeneration of neurons in striatum (mostly the putamen) that leads to decreased GABA

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18
Q

When does Parkinson’s disease start?

A

Late in life (~60/70 y.o)

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19
Q

What is the average onset of Huntington’s CHorea?

A

Progressive disease beginning at 45 y.o.

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20
Q

What is the heritability of Huntington’s?

A

Autosomal dominant HTT gene mutation - CAG Trinucleotide repeat

21
Q

What is Huntington’s chorea characterized by?

A

‣ Involuntary, jerky, and rapid movements

‣ Dementia

‣ Unsteady gait, slurred speech, trouble maintaining tongue protrusion, irregular breathing

‣ Many pts. Also diagnosed w/ depression
• Not just due to chronic illness
• Higher risk of suicide

22
Q

What are treatments for Huntington’s chorea?

A

Tetrabenazine (serotonin antagonist)

Typical antipsychotic (antagonize dopamine)

Reserpine, tetrabenazine (depleting dopamine)

23
Q

What is chorea?

A

Spontaneous rapid, jerky, arrhythmic, and involuntary movements which are purposeless, or fragments of motor programs

24
Q

What is Ballismus caused by?

A

Lesion of the CONTRALATERAL subthalamic nucleus

25
What is Ballismus characterized by?
Flailing, flinging movement of whole extremity
26
What is Ballismus related to?
Stroke, inflammation or tumor
27
What is Athetosis?
Inability to sustain body part in one positions, w/ movements of a snake-like or writhing fashion
28
What is Athetosis often seen with?
Chorea
29
What characterizes Athetosis?
Slow, writhing, continuous movements
30
What is Athetosis dcaused by?
Dopamine blocking drugs, or hypoxicischemic injury
31
What is focal Dystonia? What kind of pain does it cause?
Writer’s cramp - a persistence or fixing of posture at extreme of an athetoid movement of extremities or trunk Not painful, just impaired ability to write bc of involuntary , sustained muscle contracture of extensor and/or flexors of hand
32
What are other kinds of Dystonia seen?
Torticollis (cervical Dystonia) Blepharospasm Drug induced
33
What is Sydneham’s Chorea?
Neurological disorder of childhood resulting form acute rheumatoid fever.
34
What is the JONES criteria for syndenham’s chorea?
* J = joints (arthritis) * <3 = heart (-carditis) * N = Nodules (subcutaneous) * E = Erythema marginatum * S = Sydenham’s chorea
35
What is Syndenham’s chorea characterized by? Who does it affect more?
rapid, irregular, and aimless involuntary movements of the arms and legs, trunk, and facial muscles It affects girls more often than boys and typically occurs between 5 and 15 years of age.
36
The basal ganglia provide feedback tot he cortex to either ___ or ____ What does this allow for?
Stimulate motor activity OR inhibit motor activity Allowing for complex movements
37
What is the modifier in the direct pathway?
Cortex activates pars Compacta to modify striatum via D1 and dopamine Pars compacta will stimulate straitum to further release gaba to GPi and Pars Reticulata
38
What is the modifier in the indirect pathway?
Cortex activates Pars compacta to modify striatum via D2 and dopamine Will inhibit striatum and allow for GABA to work on GPe, allowing for STN to activate GPi and further inhibit thalamus
39
What is affected to cause Wilson’s disease?
Globus pallidus Internus and striatum
40
What does GPi do?
Inhibit thalamus via GABA
41
What does GPe do?
Inhibit STN via GABA
42
What 2 things inhibit the thalamus at rest? | What is this called?
GPi Substantia nigra Pars reticulata Tonic inhibition of thalamus
43
How is the striatum activated during the direct pathway? What does this allow it to do?
Cortex releases glutamate to striatum Striatum releases gaba to GPi —> can no longer inhibit thalamus Pars Reticulata —> can no longer inhibit thalamus
44
What is the role of the subthalamic nucleus during the indirect pathway?
Once uninhibited from GPe STN will stimulate GPI which will then go and inhibit thalamus
45
What is the skeletomotor loop? Role of it?
Motor cortex —> putamen —> VA and VL role in control of glacial, limba and musculature
46
What is the Oculomotor Loop? Role?
from eye field (posteiror parietal, prefrontal) —> Caudate —> VA and Medial dorsal role in control of saccadic eye movements
47
What is the associative loop? Role?
from post. Parietal and middle and inferior temporal lobe —> caudate —> Va and Medial Dorsal Role in cognition and executive behavioral functions
48
What is the limbic loop? Role?
from medial and lateral temporal lobes and hippocampal formation (ant. cingulate gyrus) —> ventral striatum —> Ventral pallidum —> Medial dorsal and VA Participates in the motivational regulation of behavior and emotions