Chapter 11: Motor Control and Plasticity Flashcards
(105 cards)
1
Q
Spinal Reflexes
A
Connections between sensory information via dorsal root and motor output via ventral root.
2
Q
What is an example of a spinal reflex?
A
Simple knee jerk
3
Q
Is motor activity a simple movement?
A
No, it is a complex, sequential patterns of behavior
4
Q
What controls motor activity?
A
Constant feedback and anticipation from the brain.
5
Q
What are the 5 motor systems?
A
- Skeletal system (muscles)
- Spinal cord
- brainstem
- Primary and adjacent motor cortex
- Non-cortical brain regions
6
Q
Electromyography (EMG)
A
Records the muscles AP like they do with neurons.
7
Q
Feedforward Control
A
The command specifies the response.
8
Q
What is an example of feedforward control?
A
Gastrocnemius Contraction
9
Q
Feedback Control
A
The command specifies a desired state.
10
Q
How do muscles control the skeletal system?
A
They contract, which pulls the two ends of a joint closer together.
11
Q
Muscles can create force only through…
A
Contraction
12
Q
What reverses the contraction of muscles?
A
Relaxation
13
Q
Antagonists
A
Muscles that oppose each other
14
Q
How does muscle innervation work?
A
- Motoneurons release ACh at motor end plates which activate nACh receptors
- AP is created
- AP enables sodium and calcium to enter the muscle cell.
- The changes in levels causes actin and myosin to contract the muscle.
15
Q
Motor Unit
A
Motoneuron and all the fibers it innervates
16
Q
Low Ratio
A
One motoneuron innervates very few muscle fibers
17
Q
Low ratio leads to…
A
fine motor control
18
Q
High ratio leads to…
A
Massive muscles
19
Q
Fast Twitch Fibers
A
React quickly and strongly but tire quickly
20
Q
What are fast twitch fibers used for?
A
Activities where muscle contraction changes frequently
21
Q
Slow Twitch Fibers
A
Slower response but do not tire as quickly
22
Q
What is an example of slow twitch fibers?
A
Posture
23
Q
What two things do slow twitch fibers have?
A
- low threshold
- weak contraction
24
Q
Proprioception
A
The sensory system for your muscles, tendons, and joints.
25
What is proprioception crucial for?
knowing where your body is in space
26
What are the two major parts of proprioception?
1. Golgi tendon organs
2. Muscle spindles
27
Intra fusal Muscle Fibers
Important for sensing muscle stretch
28
Extra Fusal Muscle Fibers
Produce the force of contraction
29
Primary Sensory Endings
Respond to changes in muscle length
30
Secondary Sensory Endings
Provide information about state of muscle stretch
31
Gamma Motor Neuron
Contracts intra fusal fibers to change range of sensitivity
32
Golgi Tendon Organ
Monitors muscle tension via contractions of the muscle
33
Where is the golgi tendon organ located?
Tendon (sensor nerve endings)
34
What can the golgi tendon organ detect?
Overloads (prevents tearing and damage)
35
What needs to be present for muscle spindles to work?
Intra fusal muscle fibers
36
What happens if the intrafusal muscle fibers are not present?
Would no longer be able to signal changes in stretch because the spindle would not be stretched anymore.
37
Some reflexes are entirely...
Spinal
38
Spinal Reflexes
The spinal cord is responsible for some rhythmic patterns of motor behavior
39
What is an example of a spinal reflex?
Basic parts of walking
40
Central Pattern Generator
Neural circuit is responsible for generating the basic rhythms
41
Brainstem
Direct control over motor output of cranial nerves
42
How are muscles controlled if they are not controlled through the brainstem?
Motor neurons in the spinal cord.
43
What are the two major pathways of the motor system?
1. Pyramidal Motor System (corticospinal system)
2. Extrapyramidal Motor Systems
44
Pyramidal Motor System (corticospinal system)
Axons pass through the pyramid of the medulla.
45
Extrapyramidal Motor Systems
Starts within the reticular formation of the brainstem, and moves through the spinal cord.
46
Where is the primary motor cortex (M1) located?
Pre-central Gyrus
47
What does the primary motor cortex show?
The highest firing rates for movement in a particular direction
48
How do we get precise movements?
1. Neuron activity
2. Neurons aggregated togethers
3. Neuron population
49
M1 shows plasticity like the ____
Somatosensory cortex
50
What can TMS be used for?
Induce the activation of neurons
51
What is an example of plasticity of the motor cortex?
Learning a new type of movement
52
Supplementary Motor Area (SMA)
Appears to be crucial for voluntary movement, especially initiating movement sequences
53
Premotor Cortex
Crucial when movements are guided by external stimuli, and maps specific kinds of behaviors
54
Mirror Neurons
Brain cells that are activated when someone performs/observes another person performing the same action.
55
What are the most prominent components of the extrapyramidal systems?
1. Cerebellum
2. Basal ganglia (MOST IMPORTANT)
56
The extrapyramidal system includes...
tracts of axons outside of the pyramid of the medulla
57
What happens when there is a lesion to the extrapyramidal system?
Interference with reflexes, but not individual movements.
58
What are the two principal tracts of communication to the spinal cord?
1. Reticulospinal Tracts
2. Rubrospinal Tract
59
Reticulospinal Tracts
Run from reticular formation (brainstem) to spinal cord; can facilitate/inhibit motor output.
60
Rubrospinal Tract
Runs from the red nucleus to the spinal cord; regulates motor output
61
Corticospinal tracts
Have direct control over movements
62
Extrapyramidal systems
Modulate activity = prevent erratic movements, maintain muscle tone, and postural stability.
63
Basal Ganglia
Collection of subcortical nuclei that regulate amplitude and direction of movement
64
What does the basal ganglia maintain?
Topography
65
Cerebellum
Receives input from sensory and motor systems
66
How does the cerebellum guide movement?
Inhibiting neurons
67
Muscular Dystrophy (MD)
Group of disorders characterized by biochemical abnormalities in muscles
68
What happens to muscles when someone has MD?
The muscles waste away
69
Duchenne’s
Caused by mutation in dystrophin gene (x-linked disorder)
70
What disorder of the motor system is most common and fatal?
Duchenne's
71
Myasthenia Gravis
Autoimmune disorder where your own antibodies attack ACh receptors
72
What does Myasthenia Gravis result in?
The weakness of skeletal muscles
73
When does Myasthenia Gravis become life threatening?
When swallowing - respiration is affected
74
Polioviruses
Attack and destroy motoneurons in the spinal cord.
75
What type of nerves can the poliovirus attack?
Cranial nerves
76
What happens to muscles when someone has polioviruses?
The muscles weaken/die due to disuse
77
What disorder is almost entirely destroyed due to the emergence of vaccines?
Polioviruses
78
Amyotrophic Lateral Sclerosis (ALS)
Motoneurons in the brainstem and spinal cord die, causing muscles to weaken and die.
79
What disorder is known as Lou Gehrig's disease?
ALS
80
10% of ALS cases are...
hereditary
81
In 20% of hereditary ALS cases, ALS is resulted from...
damage to the mitochondria
82
4 Strategies for Reconnecting the Spinal Cord and Brain
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
Strokes
Usually occurs on one side of the body and can produce plegia (paralysis) or paresis (weakness)
84
What usually occurs when a stroke happens?
Spasticity (loss of normal motor inhibiton)
85
What can produce complex behavior changes?
Damage to non-motor areas
86
Apraxia
Inability to carry out movements but with NO paralysis or weakness of muscles.
87
Ideomotor Apraxia
Inability to carry out simple motor activity.
88
Ideational Apraxia
Impairment in carrying out sequence of actions.
89
Parkinson's Disease
Motor symptoms are caused by the loss of dopamine input to caudate-putamen (striatum) - SN cells degenerate
90
When was Parkinson's Disease first identified?
200 years ago
91
What are the symptoms of Parkinson's Disease?
Tremors, loss of facial muscle tone, difficulty initiating movements, and general difficulty in all motor activities.
92
What are the 2 treatments of Parkinson's Disease?
1. L Dopa
2. Deep Brain Stimulation (DBS)
- severe cases
93
L Dopa
Precursor to dopamine, gets converted to dopamine in the brain
-Does nothing to reverse neuronal degeneration
94
Frozen Addict Case
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
When does MPTP become highly toxic?
When it is converted to MPP+
96
What does the frozen addict case model?
Parkinson's in primates
97
Huntington's Disease
Clumsiness and small twitches
98
What does Huntington's Disease lead to?
constant stream of involuntary movements and writhing of the body
99
How long do people with Huntington's Disease usually live for after symptoms arise?
20 years
100
What disorder is inherited?
Huntington's Disease
101
Gene HTT
Produces the protein hungtingtin
102
What is the problem with the gene in HD?
It is abnormally lengthened due to the trinucleotide repeating.
103
How many repeats of the nucleotide causes Huntington's Disease?
38+
104
What happens when the spinocerebellum is damaged?
develops abnormal gait and ataxia, leading to the loss of coordination of the legs.
105
What happens when the cerebrocerebellum is damaged?
Develops various motor problems, including the decomposition of movement
