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Flashcards in Exam 4: L5 Deck (34)
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1
Q

Major Components of the Basal Ganglia:

  1. Dorsal Striatum
    * *
  2. Globus Pallidus:
    * *
  3. Substantia Nigra
    * *
  4. Subthalamic Nucleus
A

Major Components of the Basal Ganglia:

  1. Dorsal Striatum:
  • caudate nucleus
  • putamen
  1. Globus Pallidus
  • Lateral aka external
  • Medial aka internal
  1. Substantia Nigra
  • Pars reticulata
  • Pars compacta - dopaminergic
  1. Subthalamic Nucleus
2
Q

What is the core function of the basal ganglia?

A

The core function of the basal ganglia is to choose between mutually exclusive actions

3
Q

Action Selection:

  • purpose of the _____
  • process of selecting and promoting one action while
  • ideally: strategy of selection favors _____

Relevant Neurophysiatric Disorders:

A

Action Selection:

  • Purpose of the highly conserved basal ganglia circuitry
  • process of selecting and promoting one action while supressing competing actions
  • Ideally: strategy of selection favors emotional and physical state
  • Relevant Neurophysiatric Disorders:
  • OCD
  • ADHD
  • Tourette’s
4
Q

The basal ganglia default condition is _______

A

The basal ganglia default condition is to do nothing

5
Q

Basal Ganglia Default Setting?

At rest the basal ganglia ______

Basal ganglia releases _____ when the action becomes important or ______

A

Basal Ganglia Default Setting: TO DO NOTHING

At rest, the basal ganglia supresses all movement

Basal ganglia releases inhibition when action becomes important or salient

  • present conditions
  • past experiences
6
Q

The basal ganglia releases ________ from inhibition

A

The basal gangli releases selected actions from supression

7
Q

Choices of Basal Ganglia Circuitry:

______ the action

What else goes along with it?

A

Choices of Basal Ganglia Circuitry:

Chose the action

How long does it continue?

Is another action more urgent?

When does the action end?

8
Q

What enables simultaneous actions?

A

Chunking together often repeated movements enables simultaneous actions

9
Q

Chunking: The ______ at work

Chunking permits a ________ to occur without the need for deliberately intending each component of the movement

  • No ________ involved
  • Plastisity of striatal afferents (explain)
A

Chunking: the striatum at work

Chunking permits a sequence of movements to occur without the need for deliberately intending each component of the movement

  • No cortical projections involved - don’t have to think about chunking, it is automatic
  • Plasticity of striatal afferents: when a series of movements keeps occuring, synpatic changes reinforce those motor circuits
10
Q

Chunking Simultaneous Movements:

Repeated selection of actions are grouped/chunked/hardwired together - aka ____

Can group chunks together as well as complex behaviors (allows for ______)

Free from contingences- free from ____

-Once actions are chunked, _____

A

Chunking Simultaneous Movements:

Repeated selection of actions are grouped/chunked/hardwired together - aka habits

Can group chunks together as well as complex behaviors (allows for multitasking)

Free from contingenies - independent from the outcome

Once actions are chunked - difficult to interrupt

11
Q

Pathways through the basal ganglia employ____

A

Pathways through the basal ganglia employ the same input and output ports

12
Q

Basal Ganglia Inputs and Outputs

What are the basal ganglia input areas?

Basal ganglia output areas?

A

Basal Ganglia

Inputs: Caudate and Putamen (within striatum)

Outputs:

  • Internal globus pallidus
  • substantia nigra parts reticulata
13
Q

Feature of basal ganglia loops:

Number of inputs is greater/lesser than number of outputs

Default state of ______ is maintained by ___, ___ output

Medium spiny neurons = 90% of _____ neurons, ____-ergic

A

Feature of Basal Ganglia Loops:

Number of inputs is greater than number of outputs

Default state of no action is maintained by tonic GABAergic, inhibitory output

Medium spiny neurons = 90% of striatum neurons, GABA-ergic, spine covered dendrites

14
Q

Cortical and Subcortical Loops

A
15
Q

The ________ loop uses efference copy, and sensory and cognitive information to achieve action selection

A

The skeletomotor loop uses efference copy, and sensory & cognitive information to achieve action selection

16
Q

Skeletalmotor Loop Action Selection:

  • Explain the term “efference copy”
  • Sesory, cognitive information
  • Urgency or saliency of different actions
A

Skeletalmotor Loop Action Selection:

-Efference Copy: signal that serves as gold standard to which actual movement is compared

  • neural copy of intended or desired outcome “corollary discharge”
  • bias towards current actions, behavioral continuity

Sensory, cognitive and afferent into

Urgency or saliency of different actions

  • importance of different actions, including the current action being performed
17
Q

What does operational learning provide?

A

Operational Learning provides critieria with which to choose between actions

18
Q

Operational Learning

  • _________ process executed by the basal ganglia
  • Instrumental, procedural, operant or reinforcement learning
  • Process by which we associate our actions with ___
  • Implicit Learning: we learn effects of self-generated actions
  • biases our actions towards ones associated with ____
A

Operational Learning:

  • Unconcious, associated process executed by the basal ganglia
  • Instrumental, procedural, operant or reinforcement learning
  • Process by which we associate our actions with their immediate concequences
  • Implicit learning: we learn effects of self-generated actions
  • biases our actions towards ones associated with rewards and away from ones with negative concequences
19
Q

Basal Ganglia Functions and purpose:

  • Action Selection: basal ganglia ______
  • Brain ________ via chunking
  • In operational learning, chunked actions when associated with ______ are repeated
A

Basal Ganglia Functions and Purpose:

  • Action Selection: basal ganglia orchestrates what movements occur
  • Brain groups multiple actions together via chunking
  • In operational learning, chunked actions when associated with positive rewards are repeated
20
Q

Explain the following Skeletomotor Loop Pathways:

  1. Hyperdirect pathway (global inhibition)
  • through the _____
  • stops what?
  1. Direct pathway (action initiation)
  • through the ____ and ____
  • releases a ____ from _____
  1. Indirect pathway (selective inhibition)
  • through _____, ___, ___
  • mixed effects
  1. Lateral Inhibition:
  • local circuits
  • facilitate ______ actions
  • opposes ____ on action selection
A
  1. Hyperdirect pathway (global inhibition)
  • through the subthalamus
  • stops current movements immediately
  1. Direct pathway (action initiation)
  • through the putamen and GPi
  • releases a selected movement from suppression
  1. Indirect Pathway (selective inhibition)
  • through the putamen, subthalamus, and GP
  • mixed effects
  1. Lateral Inhibition:
  • local circuits
  • facilitate “winning actions”
  • opposes indecision in action selection
21
Q

Dopaminergic Projections of the basal ganglia:

  1. Substantia nigra pars compacta
  2. VTA, nucleus acummbens

Dopamine is required for all _____ movements

Dopamine facilitates _____ and modification of motor sequences as ____

A

Dopaminergic projections of the basal ganglia:

  1. Substantia nigra pars compacta:
    * movement- need tonic release of dopamine to function optimally
  2. VTA, nucleus acumbens - reward pathway

Dopamine is required for all goal-directed movements

Dopamine facilitates learning and modification of motor sequences as chunks

22
Q

Dopamine and movement:

Dopamine promotes movement in a _____ fashion

Decrease in dopamine:

    • disease

Increase in dopamine:

What is “tardive dyskinesia”?

A

Dopamine and Movement:

Dopamine promotes movement in a graded fashuon

Decrease in Dopamine:

  • hypokinesia, akinesia
  • Parkinson’s Disease

Increase in dopamine:

  • excessive movement
  • Amphetamines or cocaine

Tardive Dyskinesia: after long term treatment of a dopamine antagonist, develop super sensitivity to dopamine

23
Q

The hyperdirect pathway _____ movement

Hyperdirect pathway:

  • Axons from M1 to STN are ____
  • Deep Brain Stimulation for Parkinson’s…… decreases STN output…

Impulsivity issues

A

The hyperdirect pathway opposes movement

Hyperdirect pathway:

Axons from M1 to STN are myleinated (fast)

Deep Brain stimulation for parkinson’s decreases STN output

Impulsitivity Issues

24
Q

Hemiballismus is a ______ disorder that involves what?

A

Hemiballismus is a hyperkinetic disorder that involves involuntary failing of limbs

25
Q

Hemiballism:

  • symptoms:
  • etiology
    • damage to _____
    • lesions to putamen, thalamus, or deep white matter
  • Common causes:
  • Treatments: aimed at cause of lesion, dopamine receptor _______
A

Hemiballism:

  • symptoms: violent throwing of arms and legs
  • etiology:
    • damage to contralateral subthalamic nucleus
    • lesions to putamen, thalamus, or deep white matter
  • Common Causes:
    • focal stroke
    • hyperglycemia (secondary to T2DM)
    • Toxoplasmosis lesion from HIV
  • Treatments: aimed at cause of lesion, dopamine receptor antagonist
26
Q

The direct pathway does what?

Direct Pathway:

  • sensorimotor cortex input to the _____ via ______ axons

Direct Pathway is DISINHIBITION, meaning inhibiting inhibition, removing _______ from thalamic neurons

A

Direct pathway releases selected movements from ongoing supression

Direct Pathway:

  • sensorimotor cortex input to the putamen via unmyelinated axons

Direct pathway: removes tonic inhibition from thalamic neurons

27
Q

Indirect pathways do what?

A

Indirect pathways keep rival movements supressed

28
Q

Parkinson’s disease can be viewed as a disorder of the ______ pathway

A

Parkinson’s can be viewed as a disorder of the direct pathway

29
Q

Parkinson’s Disease:

What is the prevalence of people over 50 with parkinson’s?

Etiology: degeneration of substantia nigra ______

A

Parkinson’s Disease:

  • 5-10% of people over the age of 50
  • Etiology : degeneration of substantia nigra pars compacta
30
Q

Parkinson’s Disease:

symptoms:

Treatments:

1.

2.

3.

A

Parkinson’s Disease:

Symptoms

  • hypo-, brady-, or a-kinesia
  • resting tremor
  • rigidity

Treatment:

  • L-DOPA
  • Pallidotomy (GPi)
  • STN deep brain stimulation
31
Q

Parkinon’s Disease: The direct and indirect pathways

Direct Pathway: movement initiation is more difficult due to ________

Indirect Pathway: Excessive movement _____ through disinhibition

Normally there is a balance between D1 (+) and D2 (-) input coming from the _____

A

Parkinson’s Disease: The direct and indirect pathways

Direct pathway: movement initiaiton is more difficult due to disfacilitation (decrease excitation by D1R)

Indirect pathway: Excessive movement inhibition through disinhibition

Normally there is a balance between D1 and D2 inputs through the SNpc

32
Q

Huntingon’s Disease:

4-5 million in the US, adult onset

Etiology: ______ repeat mutation on the huntington gene in chromosome 4 results in degeneration of _____ neurons, affecting the _____ pathway at least at first

A

Huntington’s Disease:

4-5 million in the US, adult onset

Etiology: CAG repeat mutation on the huntington gene in chromosome 4 results in degeneration of striatum neurons, affecting the indirect pathway at first

33
Q

Huntington’s Disease:

Symtoms:

  • initial ____kinesia
  • chlorea (explain what this means)
  • progressively becomes ___kinetic as pallidal and nigral neurons die

Treatment?

A

Huntington’s Disease:

Symptoms

  • initial hyperkinesia
  • chlorea (quick jerky dancing movements of extremities)
  • progressively becomes akinetic as pallidal and nigral neurons die

Treatment: no cure, treatments focus on symptoms

Genetic test available

34
Q

Explain the differences between the basal ganglia and the cerebellum:

Basal Ganglia:

  • _____ & ______ input
  • receives information about?
  • ensures _____ actions take priority

Cerebellum:

  • ______ or _____ input
  • receives info about?
  • Ensures that all movements are ____
A

Basal Ganglia vs the cerebellum:
Basal Ganglia:

  • cortical and subcortical inputs
  • receives info about moveemnts and actions
  • ensures salient actions take priority

Cerebellum:

  • peripheral or spinal input
  • receives info about muscle contractions
  • ensures that all movements are smooth