L18: Basal Ganglia - A Flashcards

1
Q

The basal ganglia include nuclei deep within cerebrum around the lateral ventricles and nuclei located in the ___ and ___ (subcortical structures)

A

(1) Diencephalon
(2) Midbrain

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2
Q

Functions of the Basal Ganglia?

A
  • Coordination of voluntary movements
  • Program/planning of movements
  • Limbic circuits
  • Cog/Behavioral functions
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3
Q

Which symptoms would you expect to see in someone with damage to their Basal Ganglia?

A

-Involuntary movements
-Altered muscle tone

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4
Q

Common terminology used to refer to combinations of three telencephalic nuclei?

A

1) Corpus Striatum
2) Striatum
3) Lenicular Nucleus

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5
Q

____: Caudate Nucleus + Putamen
A. Corpus Striatum
B. Striatum
C. Lenicular Nucleus

A

B. Striatum

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6
Q

____: Large C shaped nucleus that lies in the lateral wall of the lateral ventricle

______: Crescent shaped nucleus; is histologically similar to caudate nucleus (both originate from same embryological origin)

A

Caudate Nucleus
Putamen

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7
Q

The striatum contains populations of neurons that use either ___ or ____

A

GABA/Ach

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8
Q

Which neurotransmitter does the neurons of the Globus Pallidus use?
A. Ach - Excitatory
B. GABA - Inhibitory

A

B. GABA - Inhibitory

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9
Q

Which segment of the Globus Pallidus provides the major output of the corpus striatum + projects to the VA/VL nuclei of the thalamus?

A. Internal (Medial) Segment
B. External (Lateral) Segment

A

A. Internal (Medial) Segment

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10
Q

____: Projects to the internal segment of the GP and the subthalamic nucleus + gets input from striatum

A. Internal (Medial) Segment
B. External (Lateral) Segment

A

B. External (Lateral) Segment

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11
Q

The Substantia Nigra is a large nucleus located in midbrain tegmentum. It is subdivided into which two areas?

A
  1. Pars Compacta
  2. Pars Reticulata
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12
Q

Which part of the Substantia Nigra uses GABA as a NT? Which part uses DA?

A

Substantia Nigra
DA =Pars Reticulata
GABA = Pars Compacta

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13
Q

True or False: The Pars Compacta is the part of the Substantia Nigra that contains neuromelanin

A

True

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14
Q

Which structure is the principal source of dopamine to the striatum via the nigrostriatal tract?

A

Substantia Nigra

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15
Q

True or False: The subthalamic nucleus is integrally connected to the striatum and substantia nigra

A

True

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16
Q

In general, most inputs are TO the ___ while most outputs are FROM the ___

A

Striatum; GPi

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17
Q

True or False: The Basal Ganglia contains neurons that are both excitatory and inhibitory that work together to form modulatory loops within basal ganglia

A

True

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18
Q

Which two sites are the main receiving sites of basal ganglia input?

A
  1. Caudate Nucleus
  2. Putamen
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19
Q

Corticostriate inputs are excitatory and use ____ as a neurotransmitter

A

glutamate

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20
Q

What are the two neuronal cell types in the striatum?

A
  1. GABAergic spiny neurons
  2. Cholinergic Interneurons
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21
Q

Which neuronal cell type of the striatum uses Ach (excitatory) and constitutively activates neurons?
A. GABAergic Spiny Neurons
B. Cholinergic Interneurons

A

B. Cholinergic Interneurons

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22
Q

Which neuronal cell type of the striatum uses GABA (inhibitory) and its activation leads to inhibition and neuromodulation of target neurons?
A. GABAergic Spiny Neurons
B. Cholinergic Interneurons

A

A. GABAergic Spiny Neurons

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23
Q

True or False: The GABAergic Spiny Neurons are the main neurons involved in direct/indirect pathway

A

True

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24
Q

How does the substantia nigra provide dopaminergic inputs to the striatum?

A

Nigrostriatal fibers

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25
Q

When dopamine binds to the ___ receptors of the striatum, it has an EXCITATORY effect. Plays significant role in DIRECT PATHWAY, via basal ganglia.

A. D1 Receptors
B. D2 Receptors

A

A. D1 Receptors

26
Q

When dopamine binds to the ___ receptors of the striatum, it has an INHIBITORY effect. Plays significant role in INDIRECT PATHWAY, via basal ganglia.

A. D1 Receptors
B. D2 Receptors

A

B. D2 Receptors

27
Q

How does the striatum project to both segments of the globus pallidus (GPe and GPi)?

A

Striatopallidal projections

28
Q

Fibers of the striatopallidal projections use ___ and are inhibitory

A

GABA

29
Q

How does the striatum project to the substantia nigra? Which NE does it use?
A. Striatonigral fibers
B. Striatopallidal projections

A

A. Striatonigral fibers

  • GABA (inhibitory)
30
Q

____ _____ projects to the internal segment of the globus pallidus (GPi). These projections use which NT?
A. Thalamus
B. Subthalamic Nucleus
C. Thalamic Nucleus

A

B. Subthalamic Nucleus; Glutamate (excitatory)

31
Q

Which part of the globus pallidus is the main source of outputs from the corpus striatum?
A. GPe
B. GPi

A

B. GPi

32
Q

Which part of the globus pallidus projects to the VA/VL Thalamic Nuclei?
A. GPe
B. GPi

A

B. GPi

33
Q

Pallidothalamic projections use ___ (NT) and are inhibitory

A

GABA

34
Q

Basal ganglia interconnections are all ___. Thus, their indirect effects on the cerebral cortex influence motor control on the ___ side of the body through the corticospinal system.
A. ipsilateral; contralateral
B. contralateral; ipsilateral

A

A. ipsilateral; contralateral

35
Q

True or False: The Direct and Indirect Pathway facilitates the flow of information through the thalamus

A

False - The Direct Pathway does, but the Indirect Pathway inhibits the flow of information through the thalamus

36
Q

Which pathway utilizes D1 dopamine receptors in striatum + leads to increased movements/cortical and thalamic activity?
A. Direct Pathway
B. Indirect Pathway

A

A. Direct Pathway

37
Q

Which pathways utilizes the D2 dopamine receptor group in the striatum + leads to decreased thalamic activity/cortical activity/movement?
A. Direct Pathway
B. Indirect Pathway

A

B. Indirect Pathway

38
Q

Which structures is key to activation of the Indirect Pathway?

A

Subthalamic Nucleus

39
Q

True or False: The nigral and pallidal inputs to the thalamus are tonically active, even at rest.

A

True

40
Q

If a voluntary movement is wanted, which pathway will become more active?

If no movement is wanted, which pathway will become more active?

A

Movement = Direct Pathway

No movement = Indirect Pathway

41
Q

What does the Direct Pathway look like??

A
42
Q

Label 1-4:

A

1: Corticostriate projections
(cortex to striatum)

2: Striatopalladal projections
(striatum to GPi)

3: Palladothalamic projections
(GPi to Thalamus)

4: Thalamocortical projections
(Thalamus to Primary Motor Cortex)

43
Q

Explain how this pathway works:

A
44
Q

When the Direct Pathway is activated, a sub-cat of ____ neurons are turned on. These neurons act to INHIBIT the inhibitory ___ neurons, which leads to ACTIVATION (disinhibition) of the ____, eliciting movement

A. striatopalldal, pallothalamic, thalamus
B. thalamus, pallothalamic, striatopall

A

A. striatopalldal, pallothalamic, thalamus

45
Q

What does the Indirect Pathway through the basal ganglia look like?

A
46
Q

Describe what is happening in
1-5:

A
47
Q

When the Indirect Pathway is activated a subcategory of striatopalladal neurons are turned on, which leads to increased activation of ___ nucleus.

Neurons of ___ nucleus excite the inhibitory ____ palladothalamic neurons, which leads to inhibition of __ and decreased movement

A

subthalamic; subthalamic nucleus; thalamus

48
Q

True or False: The cortical signal activating the Indirect Pathway results in turning DOWN motor activity and leads to DECREASED movement

A

True

49
Q

The starting point for the motor loop going through the basal ganglia is always an activation of ___ neurons due to release of ___ from cortico-striatal projection

A

striatal neurons; glutamate

50
Q

True or False: Spiny neurons in the striatum express either D1 or D2-R’s. D1 are excitatory while D2 is inhibitory

A

True

51
Q

Which NT excites the Direct Pathway?

Which NT excites the Indirect Pathway?

A

Direct = Dopamine
Indirect = Ach

52
Q

The direct pathway is activated by neurons expressing the ___ receptor, which are excited/activated when dopamine is release into the striatum
A. D1
B. D2

A

A. D1

53
Q

True or False: The Direct Pathway is excited/turned UP by dopamine, whereas the Indirect Pathway is inhibited/turned DOWN by dopamin

A

True

54
Q

What is the net effect of dopamine?

A

Increased motor activity and movement

55
Q

As a positive feedback to further release dopamine, the striatum also sends GABAergic projections to GABAergic cells of the ___ ___

What are the two inhibitory effects?

A

pars reticulata

  1. Further disinhibition of thalamus by inhibiting pars reticulata inhibitory neurons
  2. Inhibiting the inhibitory projections of pars reticulata to the pars compacta, which further enhances dopamine release
56
Q

Which condition is caused by LOSS of dopaminergic input to striatum from the substantia nigra (pars compacta)?

In this condition, which system is dominant, leading to lack of movement?

A

Parkinson’s Disease
- The indirect system predominates

57
Q

Which NT activates striatal spiny neurons expressing D2-R and inhibits D1 neurons?

A

ACh

58
Q

True or False: Ach ultimately activates the Indirect Pathway, turning down motor activity and decreasing movements on contralateral side of the body

A

True

59
Q

Which condition results due to loss of cholinergic interneurons in the striatum? In this condition - which pathway is dominant?
A. Parkinson’s
B. Chorea

A

B. Chorea
- Direct system is dominant

(due to loss of inhibition of Direct Pathway and loss of control of Indirect Pathway, leading to excessive, unwanted, uncontrollable movements)

60
Q

True or False: Both the basal ganglia and cerebellum are important for INITIATION + early PROCESSING of motor activities

A

True

61
Q

True or False: The basal ganglia influences motor movements, even though they have no direct connection to LMN

A

True