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Human Physiology 2 - Unit 2 - Zach H. > Lecture 13: Contributions of Cerebellum & Basal Nuclei to Motor Function II > Flashcards

Lecture 13: Contributions of Cerebellum & Basal Nuclei to Motor Function II Flashcards

1
Q

What does the basal nuclei function to do?

A

Help to plan and control complex patterns of muscle movements, controlling relative intensities of the separate movements, directions of movements, and sequencing of multiple successive and parallel movements.

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2
Q

What does the basal nuclei do?

A
  • plan and execute motor commands in concert with cerebral cortex; help cortex execute subconscious but learned pattern.
  • help plan multiple parallel sequential patterns.
  • control complex patterns of motor activity.
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3
Q

Where does the basal nuclei receive most of its input from?

A

cerebral cortex

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4
Q

Where does the basal nuclei return mots of its output to?

A

cerebral cortex

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5
Q

What is the principle role of the basal nuclei?

A

Work with corticospinal system to modulate thalamic output to the motor cortex to plan and execute smooth movements.

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6
Q

Which paired nuclei make up the basal nuclei?

A 
- striatum 
  > caudate nucleus 
  > putamen 
- globus pallidus 
- substantia nigra 
- subthalamic nucleus
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7
Q

What are the two major basal nuclei circuits?

A
  • Putamen circuit (direct)

- Caudate nucleus circuit (indirect)

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8
Q

What is the putamen circuit (direct pathway) for?

A

For subconscious execution of learned patterns of movement.

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9
Q

Does the putamen circuit (direct pathway) bypass the caudate nucleus?

A

Yes

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10
Q

True or False:

The putamen circuit (direct pathway) is overall excitatory, thus tending to decrease motor activity.

A

False - tends to increase motor activity (overall excitatory).

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11
Q

What is the pathway of the putamen circuit (direct pathway)?

A

Cerebral cortex -(+)->
Putamen (substantia nigra compacta) -(-)->
Blobus pallidus (internal) and substantia nigra reticularis -(-)->
Thalamic relay nuclei (ventroanterior and ventrolateral nuclei) -(+)->
Primary motor cortex (and premotor/supplementary)

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12
Q

In the putamen circuit (direct pathway), the connections between the striatum and the substantia nigra use what neurotransmitter?

A

Dopamine

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13
Q

What receptor does dopamine bind to for an inhibitory effect?

A

D2 Receptors (indirect pathway)

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14
Q

What receptor does dopamine bind to for an excitatory effect?

A

D1 Receptors (direct pathway)

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15
Q

Is the action of dopamine in the putamen circuit (direct pathway) overall excitatory or inhibitory?

A

excitatory

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16
Q

What happens when the putamen is excited?

A

The putamen inhibits the IGP/SubNigRet and allows the thalamus to send excitatory signals to the motor cortex.

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17
Q

You know that the IGP/SubNigRet is normally active, thus sending what signals to the thalamus?

A

Sends inhibitory signals to the thalamus.

Putamen inhibits IGP/SubNigRet and allows the thalamus to send excitatory signals to the motor cortex

18
Q

What does a lesion in the globus pallidus cause?

A

> Leads to spontaneous and often continuous writhing movements of a hand, an arm, the neck, or the face.

> These movements are called athetosis.

19
Q

What does a lesion in the subthalamic nuclei cause?

A

> Leads to sudden flailing movements of an entire limb.

> A condition called hemiballismus.

20
Q

What does a lesion in the striatum cause?

A

Need to look up.

21
Q

What does a lesion in the substantia nigra cause?

A

> Leads to the common and extremely severe disease of rigidity, akinesia, and tremors known as Parkinson’s disease.

22
Q

What is the caudate circuit (indirect pathway) used for?

A

> Cognitive planning of sequential and parallel motor patterns.

plays major role in cognitive control of motor activity

23
Q

What does the caudate circuit (indirect pathway) play a major role in?

A

In cognitive control of motor activity.

24
Q

Overall, is the caudate circuit (indirect pathway) inhibitory or excitatory?

A

Over all inhibitory – tends to decrease motor activity.

25
Q

Does the caudate circuit (indirect pathway) tend to decrease or increase motor activity?

A

Tends to decrease motor activity.

26
Q

What is the neurotransmitter used between the substantia nigra and caudate nucleus and putamen?

A

Dopamine (inhibitory)

27
Q

What is the neurotransmitter used between:
caudate nucleus and putamen –>
globus pallidus and substantia nigra

A

GABA (inhibitory)

28
Q

What is the neurotransmitter used between:

Cortex –> caudate nucleus and putamen?

A

Acetylcholine (excitatory)

29
Q

What neurotransmitter is used in multiple pathways from the brain stem?

A

> norepinephrine
serotonin (inhibitory)
encephalin

30
Q

What do multiple glutamate pathways provide?

A

Provide most of the excitatory signals.

31
Q

What is anther name for Parkinson’s?

A

Paralysis agitans

32
Q

What is Parkinson’s a result of?

A

From widespread destruction of pars compacta of substantia nigra that sends dopaminergic fibers to caudate nucleus and putamen.

Dopaminergic pathways to direct and indirect pathways are lost. The direct pathway loses some of its excitatory input and the indirect pathway loses some of its inhibitory input. In both cases there is decreased motor activity.

33
Q

What are the characteristics of a patient with Parkinson’s?

A

> rigidity of much of body musculature
involuntary tremors of involved areas even at rest at a fixed rate
serious difficulty in initiating movement (akinesia)
postural instability
dysphagia, speech disorders, gait disturbances, fatigue

34
Q

When do Huntington’s patients typically become symptomatic?

A

around 30-40 years of age

35
Q

What are the characteristics of a patient with Huntington’s?

A

> flicking movements of individual muscles
progressive severe distortional movements of entire body
severe dementia
motor dysfunctions

36
Q

What are the abnormal movements in Huntington’s patients probably caused by?

A

Loss of most of cell bodies of GABA-secreting neurons of caudate nucleus and putamen and of Ach neurons in other parts of the brain.

Indirect pathway no longer has inhibitory influence on direct pathway and motor activity is increased.

37
Q

What do GABA neurons normally inhibit part of?

A

> globus pallidus

> substantia nigra

38
Q

True or False:
In patients with Huntington’s, the indirect pathway no longer has inhibitory influence on direct pathway and motor activity is increased.

A

True

39
Q

What is the pathway of the caudate circuit (indirect pathway)?

A 
Cerebral cortex -(+)-> 
Caudate nucleus -(-)-> 
Globus pallidus (external) -(-)-> 
Globus pallidus (internal) -(-)-> 
Thalamic relay nuclei (ventroanterior and ventrolateral nuclei) -(+)-> 
Premotor and supplementary motor cortex

the substantia nigra compacta sends inhibitory signals to caudate nucleus

40
Q

Draw out Direct and Indirect Pathways!!

A

Figures 57-12 and 57-11

Human Physiology 2 - Unit 2 - Zach H. (11 decks)

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