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BISC 421 - Module II > Lecture 17 - Basal Ganglia > Flashcards

Lecture 17 - Basal Ganglia Flashcards

1
Q

What are the 6 parts/associated structures of the basal ganglia?

A
  1. VA/VL complex of thalamus
  2. Subthalamic nuclei
    Caudate
  3. Putamen
  4. Globus pallidus
  5. Substania nigra pars reticula
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2
Q

What do dopaminergic neurons do?

A
  • excite some medium spiny cells

- inhibit others

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3
Q

What characterizes medium spiny neurons?

A
  • silent unless excited

- gabergic

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4
Q

What kind of inputs do medium spiny neurons receive/

A

-many excitatory cortical inputs

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5
Q

What characterizes Globus pallidus or substantia nigra?

A
  • active unless inhibited

- gabergic

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6
Q

What are the 4 major parts that form connections within the basal ganglia?

A
  1. dopaminergic neuron
  2. medium spiny neuron
  3. cortical pyramidal neurons
  4. globus pallidus or substantia nigra
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7
Q

What are the two major functions of the Basal Ganglia?

A
  1. Non-Motor loops

2. Motor loops

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8
Q

What are motor loops?

A

regulate upper motor neurons that initiate + help coordinate voluntary movement

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9
Q

What are the 2 main motor pathways?

A
  1. direct pathway (“accelerates” movement, Huntington’s)

2. indirect pathway (“brakes” movements, Parkinson’s)

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10
Q

What are 3 types of non-motor loops?

A
  1. executive/prefrontal loop
  2. limbic loop
  3. oculomotor loop
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11
Q

What is the order of the direct pathway?

A
  1. Cortex
  2. Putamen
  3. Glob. Pal. Int.
  4. VA/VL Thalamus
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12
Q

How does the direct pathway accelerate movement?

A
  • disinhibiting the thalamus

- also disinhibiting the upper motor neurons in the cortex

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13
Q

What is the order of the indirect pathway?

A
  1. Cortex excites putamen via glutamate
  2. Putamen inhibits glob. pal. ext. via GABA
  3. Glob. Pal. ext. inhibits sub thal nuc via GABA
  4. Sub Thal. Nuc. excites glob pal int via GABA
  5. Glob. Pal. Int. inhibits thalamus
  6. VA/VL Thalamus is inhibited
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14
Q

How does the indirect pathway brake movement?

A

-modulates the disinhibitory actions of the direct pathway

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15
Q

how are both the direct and indirect pathways regulated?

A

dopamine

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16
Q

Dopamine _____ the direct pathway via ____ receptors

A

excites, D1

17
Q

Dopamine _____ the indirect pathway via _____ receptors

A

inhibits, D2

18
Q

Overall, dopamine has a net ____ effect

A

excitatory

19
Q

Medium spiny cells that project to the _______ are ____ by dopamine D1 receptors

A

Glob. Pal. Int., excited

20
Q

Medium spiny cells that project to the _______ are ___ by dopamine D1 receptors

A

Glob. Pal. Ext., inhibited

21
Q

What are an example of projection neurons in the basal ganglia?

A

medium spiny neurons

22
Q

Projection neurons are _____

A

GABAergic = inhibitory

23
Q

Cells in the striatum are usually ____

A

silent

24
Q

Cells in the globus pallidus are tonically ______

A

active

25
Q

Projection neurons in the substantia nigra, pars compacta are ____

A

dopaminergic

26
Q

What are 2 categories of diseases of the basal ganglia?

A
  1. hyperkinesia

2. hypokinesia

27
Q

What are 2 types of hyperkinesia?

A
  1. hemiballismus (loss of subthalamic nucleus)

2. huntington’s disease (loss of striatum)

28
Q

What are 2 types of hypokinesia?

A
  • associated with loss of substantia nigra pars compacta
    1. Parkinson’s disease
    2. drug induced (neuroleptics, MPTP)
29
Q

What is Parkinson’s Disease characterized by?

A

loss of dopaminergic neurons in the substantia nigra

30
Q

What does loss of dopaminergic neurons lead to?

A
  • bradykinesia (slowed, impaired movement)
  • rigidity
  • “pill rolling” tremor
31
Q

What happens when dopamine is removed from the schematic?

A
  • glob. pal. int. goes into overdrive

- reduces excitation of motor thalamus via direct pathway or via indirect pathway

32
Q

What happens when the subthalamic nucleus is loss in hemiballimus?

A
  • activity in glob. pal. int. is reduced
  • VA/L receives too little inhibition, goes into overdrive
  • over excites cortex
33
Q

What does the loss of striatal neurons lead to?

A
  • subtle changes in coordination
  • severe movement disorders
  • Akinesia (patient can hear + understand, but not speak)
34
Q

What does the loss of the ptamen do?

A
  • reduces inhibition of glob. pal. ext.

- results in increased cortical activity

35
Q

What are 5 therapies for Parkinson’s

A
  1. L Dopa
  2. Thalamotomy and Pallidotomy
  3. Deep brain stimulation of subthalamic nucleus
  4. Implantation of fetal dopaminergic neurons
  5. optically gated ion channels in damaged regions

BISC 421 - Module II (14 decks)

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