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Neuroscience > Lecture 10: Basal Ganglia and Dopamine > Flashcards

Lecture 10: Basal Ganglia and Dopamine Flashcards

1
Q

what stage of movement is the basal ganglia involved in and how

A

planning

it regulates activity of UMN pathways

they turn motor programs off and on

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2
Q

what are the 5 distinct nuclei

A
  1. Caudate nucleus
  2. Putamen
  3. Globus Pallidus
    * External (indirect pathway)
    * Internal (direct pathway)
  4. Substantia Nigra
  5. Subthalamic Nucleus

Cole puked, guess sprouse’s sick CPGSS

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3
Q

where do major inputs come from

A

the cerebral cortex

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4
Q

almost all inputs synapse with what?

A

the striatum

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5
Q

what is the striatum

A

the caudate nucleus and putamen

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6
Q

what are the 2 major outputs of the basal ganglia

A

Globus pallidus internal

Substantia nigra pars reticulata

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7
Q

are the main output pathways inhibitory or excitatory

A

inhibitory

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8
Q

what is the striatum’s job

A

inhibit whatever it synapses with

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9
Q

what are the 3 main targets of outputs from the basal ganglia

A

thalamus

Reticular formation

Superior colliculus

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10
Q

what is inhibition

A

A neuron is inhibiting another neuron, preventing it from being excited

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11
Q

what is Disinhibition

A

Neuron 1 inhibits neuron 2 that would inhibit neuron 4, so now neuron 4 is disinhibited so it can get excited by neuron 3

disinhibition = excitation

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12
Q

what are the 3 basal ganglia pathways

A

Hyperdirect pathway/STOP pathway

Direct/GO pathway

Indirect/NO-GO pathway

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13
Q

what is the Hyperdirect pathway/STOP pathway

A

Stopping ongoing movements

Internal globus pallidus inhibits the thalamus

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14
Q

what is the Direct/GO pathway

A

Initiation of Movement

Thalamus is less inhibited (disinhibited)

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15
Q

what is the Indirect/NO-GO pathway

A

Stops of unwanted competing movements

Subthalamic nucleus which inhibits the thalamus

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16
Q

how are the 3 pathways working while wanting to stop drinking water so you can eat a cookie

A

Hyperdirect/Stop pathway stops me from drinking water

Direct/Go pathway gets me to reach for cookie

  • Indirect/No-go pathway prevents unwanted movements while I reach for the cookie
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17
Q

what types of programs use the Direct/GO pathway

A

Activation of intended and focused motor programs

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18
Q

what types of programs use the No-Go/Indirect and Hyperdirect Pathways

A

Broad suppression of motor programs

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19
Q

What happens with the Substantia nigra pars compacta

A

It modulates activity of both the direct and indirect pathways through dopamine release (dopaminergic pathway)

20
Q

what are the 2 types of dopamine receptors in the striatum

A

D1 receptors: Makes the direct pathway more active

D2 receptors: Makes the indirect pathway less active

21
Q

what is the Net effect of D1 and D2

A

less inhibition of thalamus = promoting movement

22
Q

what does it mean that The effects of dopamine are TRANSIENT (temporary)

A

occurs with selection of a movement

23
Q

what is the loop of the basal ganglia

A

The Basal Ganglia form a motor loop with the motor cortex in the same cerebral hemisphere

24
Q

what are the 3 motor functions of the basal ganglia

A

Inhibiting ongoing movements

Selecting and executing
movements

Inhibiting unwanted
movements

25
Q

what are the 2 non-motor loops of the basal ganglia

A

Prefrontal loop

Limbic loop

26
Q

what is the prefrontal loop

A

Initiation and termination of
cognitive processes

27
Q

what is the limbic loop

A

Regulates emotional and
motivated behaviour

Transitions from one mood state to another

28
Q

what are the 2 clinical base ganglia conditions

A

Hyperkinetic Disorders

Hypokinetic Disorders

29
Q

what are hyperkinetic disorders

A

Insufficient inhibition of the thalamus

(excessive amount of movement)

Examples:
* Huntington’s Disease
* Hemiballismus

30
Q

what are Hypokinetic Disorders

A

Excessive inhibition of the thalamus
(hard time initiating movement)

  • Parkinson’s Disease
31
Q

do Basal Ganglia lesions or damage typically result in impairments on the ipsilateral or contralateral side of the body

A

contralateral

32
Q

what is Huntington’s disease

A

Selective atrophy of the caudate and putamen

  • Progressive degeneration of striatal neurons
  • Indirect pathway affected first and is underactive; (not able to suppress unwanted movements)

eventually direct pathway becomes overactive

33
Q

what does the Indirect and direct pathways being affected in Huntington’s disease result in

A

Less tonic inhibition of the thalamus

34
Q

what is Hemiballismus

A

Lesion (e.g., stroke) affecting the subthalamic nucleus

Involuntary ballistic flinging of arm or leg Contralateral to the damage

35
Q

what is Parkinson’s Disease

A

Progressive degeneration of
dopaminergic neurons in Substantia nigra pars compacta

Direct and Indirect pathways are affected

36
Q

what are the main symptoms of Parkinson’s

A

TRAP:

Tremor
Rigidity
Akinesia - difficulty in movement
Postural instability

37
Q

how are the direct and indirect pathways affected in Parkinson’s

A

Direct Pathway
* Less D1 facilitation
↑ inhibitory output to thalamus = ↓
movement

Indirect Pathway
* Less D2 facilitation
* Excessive inhibition of the thalamus

Net effect of dopamine loss = inhibition of thalamus (↓ cortical excitability)

38
Q

why can’t we just give more dopamine to people with Parkinson’s

A

Dopamine can’t cross the blood-brain barrier

39
Q

what is the main Parkinson’s Disease Treatment

A

L-DOPA – dopamine precursor that can cross the blood-brain

Does not treat the disease itself

40
Q

what are the effects of L-DOPA for Parkinson’s

A

Effects of medication can fluctuate

Dyskinesias (involuntary movements)

Wearing off (Predictable decline in
function)

On-off fluctuations (unpredictability)

41
Q

what are the targets of Deep brain stimulation for Parkinson’s

A
  • Globus Pallidus internal
    segment
  • Subthalamic nuclei
42
Q

When dopamine is released, there is:

Less inhibition of the thalamus

Nothing happens to the thalamus

Inhibition of the frontal cortex

More inhibition of the thalamus

A

Less inhibition of the thalamus

43
Q

Which of the following statements regarding Huntington’s disease is incorrect:

It is a hyperkinetic disorder

There is increased inhibition of the thalamus

There is decreased inhibition of the thalamus

The indirect pathway is affected

A

There is increased inhibition of the thalamus

44
Q

Which pathway is affected first in Huntington’s disease?

A

Indirect pathway

45
Q

Which of the following statements is true:

None of the responses is correct

The direct pathway of the Basal Ganglia is responsible for initiating movement

The indirect pathway of the Basal Ganglia is responsible for initiating movement

The direct pathway of the Basal Ganglia is responsible for suppressing movement

A

The direct pathway of the Basal Ganglia is responsible for initiating movement

Neuroscience (20 decks)

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