Chapter 11: Motor Control and Plasticity Flashcards

1
Q

Spinal Reflexes

A

Connections between sensory information via dorsal root and motor output via ventral root.

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2
Q

What is an example of a spinal reflex?

A

Simple knee jerk

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3
Q

Is motor activity a simple movement?

A

No, it is a complex, sequential patterns of behavior

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4
Q

What controls motor activity?

A

Constant feedback and anticipation from the brain.

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5
Q

What are the 5 motor systems?

A
  1. Skeletal system (muscles)
  2. Spinal cord
  3. brainstem
  4. Primary and adjacent motor cortex
  5. Non-cortical brain regions
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6
Q

Electromyography (EMG)

A

Records the muscles AP like they do with neurons.

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7
Q

Feedforward Control

A

The command specifies the response.

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8
Q

What is an example of feedforward control?

A

Gastrocnemius Contraction

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9
Q

Feedback Control

A

The command specifies a desired state.

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10
Q

How do muscles control the skeletal system?

A

They contract, which pulls the two ends of a joint closer together.

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11
Q

Muscles can create force only through…

A

Contraction

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12
Q

What reverses the contraction of muscles?

A

Relaxation

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13
Q

Antagonists

A

Muscles that oppose each other

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14
Q

How does muscle innervation work?

A
  1. Motoneurons release ACh at motor end plates which activate nACh receptors
  2. AP is created
  3. AP enables sodium and calcium to enter the muscle cell.
  4. The changes in levels causes actin and myosin to contract the muscle.
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15
Q

Motor Unit

A

Motoneuron and all the fibers it innervates

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16
Q

Low Ratio

A

One motoneuron innervates very few muscle fibers

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17
Q

Low ratio leads to…

A

fine motor control

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18
Q

High ratio leads to…

A

Massive muscles

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19
Q

Fast Twitch Fibers

A

React quickly and strongly but tire quickly

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20
Q

What are fast twitch fibers used for?

A

Activities where muscle contraction changes frequently

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21
Q

Slow Twitch Fibers

A

Slower response but do not tire as quickly

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22
Q

What is an example of slow twitch fibers?

A

Posture

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23
Q

What two things do slow twitch fibers have?

A
  1. low threshold
  2. weak contraction
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24
Q

Proprioception

A

The sensory system for your muscles, tendons, and joints.

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25
Q

What is proprioception crucial for?

A

knowing where your body is in space

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26
Q

What are the two major parts of proprioception?

A
  1. Golgi tendon organs
  2. Muscle spindles
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27
Q

Intra fusal Muscle Fibers

A

Important for sensing muscle stretch

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28
Q

Extra Fusal Muscle Fibers

A

Produce the force of contraction

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29
Q

Primary Sensory Endings

A

Respond to changes in muscle length

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30
Q

Secondary Sensory Endings

A

Provide information about state of muscle stretch

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31
Q

Gamma Motor Neuron

A

Contracts intra fusal fibers to change range of sensitivity

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32
Q

Golgi Tendon Organ

A

Monitors muscle tension via contractions of the muscle

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33
Q

Where is the golgi tendon organ located?

A

Tendon (sensor nerve endings)

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34
Q

What can the golgi tendon organ detect?

A

Overloads (prevents tearing and damage)

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35
Q

What needs to be present for muscle spindles to work?

A

Intra fusal muscle fibers

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36
Q

What happens if the intrafusal muscle fibers are not present?

A

Would no longer be able to signal changes in stretch because the spindle would not be stretched anymore.

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37
Q

Some reflexes are entirely…

A

Spinal

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38
Q

Spinal Reflexes

A

The spinal cord is responsible for some rhythmic patterns of motor behavior

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39
Q

What is an example of a spinal reflex?

A

Basic parts of walking

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40
Q

Central Pattern Generator

A

Neural circuit is responsible for generating the basic rhythms

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41
Q

Brainstem

A

Direct control over motor output of cranial nerves

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42
Q

How are muscles controlled if they are not controlled through the brainstem?

A

Motor neurons in the spinal cord.

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43
Q

What are the two major pathways of the motor system?

A
  1. Pyramidal Motor System (corticospinal system)
  2. Extrapyramidal Motor Systems
44
Q

Pyramidal Motor System (corticospinal system)

A

Axons pass through the pyramid of the medulla.

45
Q

Extrapyramidal Motor Systems

A

Starts within the reticular formation of the brainstem, and moves through the spinal cord.

46
Q

Where is the primary motor cortex (M1) located?

A

Pre-central Gyrus

47
Q

What does the primary motor cortex show?

A

The highest firing rates for movement in a particular direction

48
Q

How do we get precise movements?

A
  1. Neuron activity
  2. Neurons aggregated togethers
  3. Neuron population
49
Q

M1 shows plasticity like the ____

A

Somatosensory cortex

50
Q

What can TMS be used for?

A

Induce the activation of neurons

51
Q

What is an example of plasticity of the motor cortex?

A

Learning a new type of movement

52
Q

Supplementary Motor Area (SMA)

A

Appears to be crucial for voluntary movement, especially initiating movement sequences

53
Q

Premotor Cortex

A

Crucial when movements are guided by external stimuli, and maps specific kinds of behaviors

54
Q

Mirror Neurons

A

Brain cells that are activated when someone performs/observes another person performing the same action.

55
Q

What are the most prominent components of the extrapyramidal systems?

A
  1. Cerebellum
  2. Basal ganglia (MOST IMPORTANT)
56
Q

The extrapyramidal system includes…

A

tracts of axons outside of the pyramid of the medulla

57
Q

What happens when there is a lesion to the extrapyramidal system?

A

Interference with reflexes, but not individual movements.

58
Q

What are the two principal tracts of communication to the spinal cord?

A
  1. Reticulospinal Tracts
  2. Rubrospinal Tract
59
Q

Reticulospinal Tracts

A

Run from reticular formation (brainstem) to spinal cord; can facilitate/inhibit motor output.

60
Q

Rubrospinal Tract

A

Runs from the red nucleus to the spinal cord; regulates motor output

61
Q

Corticospinal tracts

A

Have direct control over movements

62
Q

Extrapyramidal systems

A

Modulate activity = prevent erratic movements, maintain muscle tone, and postural stability.

63
Q

Basal Ganglia

A

Collection of subcortical nuclei that regulate amplitude and direction of movement

64
Q

What does the basal ganglia maintain?

A

Topography

65
Q

Cerebellum

A

Receives input from sensory and motor systems

66
Q

How does the cerebellum guide movement?

A

Inhibiting neurons

67
Q

Muscular Dystrophy (MD)

A

Group of disorders characterized by biochemical abnormalities in muscles

68
Q

What happens to muscles when someone has MD?

A

The muscles waste away

69
Q

Duchenne’s

A

Caused by mutation in dystrophin gene (x-linked disorder)

70
Q

What disorder of the motor system is most common and fatal?

A

Duchenne’s

71
Q

Myasthenia Gravis

A

Autoimmune disorder where your own antibodies attack ACh receptors

72
Q

What does Myasthenia Gravis result in?

A

The weakness of skeletal muscles

73
Q

When does Myasthenia Gravis become life threatening?

A

When swallowing - respiration is affected

74
Q

Polioviruses

A

Attack and destroy motoneurons in the spinal cord.

75
Q

What type of nerves can the poliovirus attack?

A

Cranial nerves

76
Q

What happens to muscles when someone has polioviruses?

A

The muscles weaken/die due to disuse

77
Q

What disorder is almost entirely destroyed due to the emergence of vaccines?

A

Polioviruses

78
Q

Amyotrophic Lateral Sclerosis (ALS)

A

Motoneurons in the brainstem and spinal cord die, causing muscles to weaken and die.

79
Q

What disorder is known as Lou Gehrig’s disease?

A

ALS

80
Q

10% of ALS cases are…

A

hereditary

81
Q

In 20% of hereditary ALS cases, ALS is resulted from…

A

damage to the mitochondria

82
Q

4 Strategies for Reconnecting the Spinal Cord and Brain

A

1.Provide stem cells to differentiate and form new neurons, in hopes that their axons will grow across the damaged region and innervate proper targets.

2.The existing axonal stumps of surviving neurons could be induced to grow across the damaged region if the proper types of glial cells are provided. = unsheathing cells

3.Lure axonal stumps to grow across the damaged region of spinal cord by providing neurotrophic factors and/or adhesive molecules.

4.If brain and spinal cord axons cannot be induced to grow across the damaged spinal cord, they can be induced to grow into a segment of peripheral nerve and grow through that “bridge” to reach the other side.

83
Q

Strokes

A

Usually occurs on one side of the body and can produce plegia (paralysis) or paresis (weakness)

84
Q

What usually occurs when a stroke happens?

A

Spasticity (loss of normal motor inhibiton)

85
Q

What can produce complex behavior changes?

A

Damage to non-motor areas

86
Q

Apraxia

A

Inability to carry out movements but with NO paralysis or weakness of muscles.

87
Q

Ideomotor Apraxia

A

Inability to carry out simple motor activity.

88
Q

Ideational Apraxia

A

Impairment in carrying out sequence of actions.

89
Q

Parkinson’s Disease

A

Motor symptoms are caused by the loss of dopamine input to caudate-putamen (striatum) - SN cells degenerate

90
Q

When was Parkinson’s Disease first identified?

A

200 years ago

91
Q

What are the symptoms of Parkinson’s Disease?

A

Tremors, loss of facial muscle tone, difficulty initiating movements, and general difficulty in all motor activities.

92
Q

What are the 2 treatments of Parkinson’s Disease?

A
  1. L Dopa
  2. Deep Brain Stimulation (DBS)
    - severe cases
93
Q

L Dopa

A

Precursor to dopamine, gets converted to dopamine in the brain

-Does nothing to reverse neuronal degeneration

94
Q

Frozen Addict Case

A

Patients were admitted to a hospital for displaying signs of Parkinson’s.

The patients were treated with L Dopa.

It was concluded that all patients has used meth (contaminated with MPTP)

95
Q

When does MPTP become highly toxic?

A

When it is converted to MPP+

96
Q

What does the frozen addict case model?

A

Parkinson’s in primates

97
Q

Huntington’s Disease

A

Clumsiness and small twitches

98
Q

What does Huntington’s Disease lead to?

A

constant stream of involuntary movements and writhing of the body

99
Q

How long do people with Huntington’s Disease usually live for after symptoms arise?

A

20 years

100
Q

What disorder is inherited?

A

Huntington’s Disease

101
Q

Gene HTT

A

Produces the protein hungtingtin

102
Q

What is the problem with the gene in HD?

A

It is abnormally lengthened due to the trinucleotide repeating.

103
Q

How many repeats of the nucleotide causes Huntington’s Disease?

A

38+

104
Q

What happens when the spinocerebellum is damaged?

A

develops abnormal gait and ataxia, leading to the loss of coordination of the legs.

105
Q

What happens when the cerebrocerebellum is damaged?

A

Develops various motor problems, including the decomposition of movement