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EP 4703: Neural Control Of Human Movement > Test 2 (Lectures 8-16) > Flashcards

Test 2 (Lectures 8-16) Flashcards

1
Q

Definition of a reflex

A

A muscle contraction induced by an external stimulus that cannot be changed by pure thinking

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2
Q

Are highly adaptable to changes in behavioral goals, but cannot be directly or voluntarily controlled

A

Reflexes

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3
Q

Stereotyped responses to specific stimuli that are generated by simple neural circuits in the spinal cord or brain stem

A

Reflexes

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4
Q

Consists of one central synapse

A

Monosynaptic reflex

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5
Q

Consists of 2-3 central synapses

A

Oligosynaptic reflex

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6
Q

Consists of many central synapses

A

Polysynaptic reflex

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7
Q

Slow, steady-state, maintained

A

Tonic

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8
Q

Fast, transient, in response to a change in the stimulus

A

Phasic

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9
Q

No higher brain involvement is involved in

A

Reflexes

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10
Q

Benefits of studying reflexes

A

It can assist in diagnosing certain conditions by localizing an injury or disease in the CNS.

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11
Q

Often indicates a disorder in one or more components of the reflex arc

A

Absent or weak (hypoactive) reflexes

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12
Q

Can cause both hyperactive and hypoactive reflexes

A

Lesions in the CNS

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13
Q

Most common form of hyperactive reflex

A

Spasticity

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14
Q

Spasticity results in

A

Increased muscle tone

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15
Q

5 Components of the reflex arc

A
  1. Sensory element
  2. Afferent nerve
  3. Central processing unit
  4. Efferent nerve
  5. Effector
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16
Q

3 components of reflex latency

A
  1. Afferent conduction delay
  2. Central processing delay
  3. Efferent conduction delay
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17
Q

This type of reflex originates from Ia spindle afferents and induces responses in the same muscle or in muscles in the vicinity

A

Monosynaptic reflex

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18
Q

Technique for examining monosynaptic reflexes developed in the 1950’s by P. Hoffman

A

H-reflex

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19
Q

Commonly assessed by stimulating the tibial nerve and measuring the response of the soleus

A

H-reflex

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20
Q

Electrical stimulation of the Ia afferents in a peripheral nerve and recording the motor response in the same muscle

A

H-reflex

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21
Q

Stimulation is applied to both afferent and efferent fibers

A

H-reflex

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22
Q

How the H-reflex and M-response work

A

Afferent fibers are the first to react to a slowly increasing electrical stimulus. They induce a reflex muscle contraction. Later, efferent fibers become excited and induce a direct muscle contraction.

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23
Q

Further increase in the strength of the stimulation leads to an increase in the _____ and a suppression of the ______.

A

M-response, H-reflex

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24
Q

How do sensory neurons conduct action potentials?

A

Antidromically

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25
Q

How do motor neurons conduct action potentials?

A

Orthrodromically

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26
Q

At high levels of stimulation, motor neurons also start generating action potentials

A

Antidromically

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27
Q

At high levels of stimulation, the antidromic motor neuron action potential cancels out the

A

antidromic sensory neuron action potential, thus suppressing the H-reflex.

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28
Q

The M-wave presents due to

A

the orthrodromic motor neuron action potential.

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29
Q

Successive stimuli at a high frequency induce

A

similar M-responses but progressively smaller H-reflexes

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30
Q

The refractory period for the ______ is much greater than the refractory period for the ________.

A

Central synapse; axon of the motor neuron

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31
Q

A ______ excites spindle endings a may induce a monosynaptic reflex contraction.

A

Tendon tap

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32
Q

The tendon tap is known as

A

the T-reflex

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33
Q

The T-reflex has the same pathway as the

A

H-reflex

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34
Q

Increases the amplitude of the H-reflex

A

Voluntary muscle activation

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35
Q

Voluntary activation of the antagonist muscle group

A

decreases the amplitude of the reflex due to Ia interneuron inhibition of the alpha motoneurons of the muscle being tested

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36
Q

How is the H-reflex amplitude increased?

A

Voluntary muscle activation excites the motoneuron pool of the activated muscle

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37
Q

Electrical stimulation of Ia afferents.
Excitation of alpha motoneurons through a central synapse.
Efferent command to the target muscle.
Twitch muscle contraction.

A

H-reflex

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38
Q

Fast stretch of a muscle, leading to activation of primary muscle spindle afferents.
Then same as H-reflex

A

T-reflex

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39
Q

Interneurons always send ____ signals.

A

Inhibitory

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40
Q

The simplest muscle reflexes acting in the human body

A

Monosynaptic reflexes

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41
Q

The functional importance of these reflexes are questionable

A

Monosynaptic reflexes

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42
Q

Induce brisk, brief, contractions that are poorly controlled voluntarily

A

Monosynaptic reflexes

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43
Q

Unlikely to be part of mechanism for voluntary control of movement

A

Monosynaptic reflexes

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44
Q

Examples of oligosynaptic reflexes

A

Ia-afferents and Ib afferents

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45
Q

Ia interneurons receive excitatory inputs from Ia afferents and make inhibitory synapses on motoneurons that innervate the antagonist muscle.

A

Reciprocal inhibition

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46
Q

Reciprocal inhibition is an example of what type of reflex?

A

Oligosynaptic inhibitory reflex

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47
Q

New thinking is that these receptors are used for fine motor control

A

Golgi Tendon Organs

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48
Q

Double inhibition is equivalent to

A

Disinhibition

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49
Q

Golgi tendon organs send Ib afferent axons to ____, which exert an inhibitory action on agonist alpha motoneurons

A

Ib interneurons

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50
Q

After inhibiting agonist alpha motoneurons, golgi tendon organs excite or _____ antagonist alpha motoneurons.

A

Disinhibit

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51
Q

Receive contributions from different receptors

A

Polysynaptic reflexes

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52
Q

Central pathway is unknown

A

Polysynaptic reflex

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53
Q

Flexor reflex is induced by a group of afferents called

A

Flexor reflex afferents

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54
Q

Includes muscle spindles, free nerve endings, cutaneous receptors, etc.

A

Flexor reflex afferents

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55
Q

Leads to an activation of flexor muscles within the limb

A

Flexor reflex

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56
Q

Emerge in response to a CHANGE in the level of a receptor specific stimulus

A

Phasic reflexes

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57
Q

Emerge in response to the level of a stimulus

A

Tonic reflexes

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58
Q

Typically a burst or brief depression of muscle activity leading to a twitchy or series of twitchy movements. All monosynaptic reflexes

A

Phasic reflexes

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59
Q

Typically lead to sustained muscle contractions and relatively smooth movements. Polysynaptic reflexes.

A

Tonic reflexes

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60
Q

Muscle spindles can lead to both

A

Phasic and tonic reflexes

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61
Q

The phasic reflexes disappear rapidly when

A

a muscle stays in its stretched state

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62
Q

Tonic changes may be observed after the stretch is completed if

A

the muscle was active before the stretch

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63
Q

6 steps of the tonic stretch reflex

A
  1. A muscle is slowly stretched by an external force.
  2. First resistance to stretching is provided by passive elastic properties.
  3. At a certain length, a few alpha motoneurons are recruited autogenically.
  4. This leads to active force development opposing the stretch.
  5. The length at which this recruitment begins is the threshold of the tonic stretch reflex.
  6. As the muscle continues to lengthen, more motoneurons and muscle force increases.
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64
Q

Reveals a relationship between muscle length and muscle force

A

Tonic stretch reflex

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65
Q

Autogenic recruitment means

A

Automatic recruitment

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66
Q

The major mechanism that defines the viscoelastic properties of muscles, joints, and limbs.

A

Tonic stretch reflex

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67
Q

The threshold is a control variable manipulated by the brain

A

Tonic stretch reflex threshold

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68
Q

Are not exclusively manipulated by the brain

A

Muscle activation levels, forces, changes in joint angles, etc.

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69
Q

Emerge with equal participation of central commands and external loads

A

Muscle activation levels, forces, changes in joint angle, etc.

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70
Q

Leads to a slow reflex increase in muscular force

A

High-frequency muscle vibration (Tonic vibration reflex)

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71
Q

Starts at a delay and lasts some time after the stimulus has ended

A

Tonic vibration reflex

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72
Q

Accompanied by a suppression of monosynaptic reflexes in the same muscle

A

Tonic vibration reflex

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73
Q

This suppresion is of a presynaptic origin

A

Suppression of monosynaptic reflexes (H-reflex, etc.) by tonic vibration reflex.

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74
Q

Receive mixed information from afferents originating from different receptors

A

Ia and Ib interneurons

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75
Q

Induces a reflex response in flexor muscles of the limb

A

Stimulation of the flexor reflexor afferents

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76
Q

Also induces a cross extensor reflex in extensor muscles of the contralateral limb

A

Stimulation of the flexor reflexor afferents

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77
Q

Reflex loop is unknown

A

Polysynaptic reflexes

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78
Q

Involve distant muscles

A

Polysynaptic reflexes

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79
Q

May show effects in other extremities

A

Polysynaptic reflexes

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80
Q

Longer latency, slow, steady-state character

A

Polysynaptic reflexes

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81
Q

Naturally occuring examples of polysynaptic reflexes

A

Flexor reflex
Crossed extensor reflex
Tonic stretch reflex

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82
Q

Artificial example of polysynatpic reflex

A

Tonic vibration reflex

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83
Q

Numerous reflex pathways exist for even

A

a single muscle

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84
Q

Controller

A

Brain

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85
Q

Variables the controller uses to formulate command signals

A

Control variables

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86
Q

Controller has the choice to ______ to peripheral information

A

React or not react

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87
Q

The controller uses independently controlled variables to formulate command signals to the “lower” (executive) structure.

A

Feedforward control

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88
Q

Examples of feedforward control

A

Soccer goalie, batter, etc.

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89
Q

Takes more time

A

Feedback

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90
Q

Commands are generated without regards to the consequences

A

Feedforward control

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91
Q

Open-loop command/control

A

Feedforward control

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92
Q

The sensorimotor loop is not completed by sensory feedback

A

Feedforward control

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93
Q

The speed of feedforward control

A

200 ms to respond to a visual stimulus

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94
Q

Is often used to start a movement, such as reaching

A

Open loop

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95
Q

Cannot correct for errors, and errors can compound

A

Feedforward control

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96
Q

Feedback control changes command signals based on their

A

outcome

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97
Q

Feedback control is done by a

A

Comparator

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98
Q

An example of a comparator in the body

A

Cerebellum

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99
Q

Changes in the output of the comparator so as to bring down any possible deviations of the output

A

Negative feedback

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100
Q

Amplifies any deviations of the output

A

Positive feedback

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101
Q

The sensorimotor loop is complete

A

Feedback control

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102
Q

Closed loop command/control

A

Feedback control

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103
Q

Uses sensory information to compare the intended action/movement to the actual action/movement

A

Feedback control

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104
Q

Can make adjustments

A

Feedback control

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105
Q

Takes time

A

Feedback control

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106
Q

Ratio of change in a control variable to change in a peripheral variable
(Change in control/change in peripheral)

A

Gain

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107
Q

Measure of time (seconds or ms)

A

Delay

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108
Q

A change in this can make an apparent negative feedback scheme function like a positive feedback scheme and vice versa

A

Delay

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109
Q

Uses both feedforward and feedback control

A

Nervous system

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110
Q

The longer the time delays in a servo,

A

the larger the errors that can accumulate before a corrective action

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111
Q

Feedback loop keeps the variable specified by the controller ____, despite possible changes in external conditions that may change the variable

A

constant

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112
Q

The servo is the same as

A

The feedback loop

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113
Q

Can shift the tonic stretch reflex to the left or decrease the delay

A

Gamma motoneurons

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114
Q

Merton’s Servo Hypothesis believes that the CNS only sends signals to the muscles through

A

Gamma motoneurons

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115
Q

Considers the feedback loop to be a perfect servo

A

Merton’s Servo Hypothesis

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116
Q

This reflex is an example of a negative feedback mechanism

A

Tonic stretch reflex

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117
Q

Suggests that the control of muscle spindles with the gamma system was part of a servo system controlling muscle length

A

Merton’s Servo Hypothesis

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118
Q

When force or torque equals load

A

Equilibrium

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119
Q

How Merton’s Servo Hypothesis works

A

If the load increases, the muscle lengthens.
Alpha motoneuron activity increases.
This increases muscular force

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120
Q

According to Merton’s Servo Hypothesis, limb displacement due to load will

A

NEVER happen

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121
Q
  1. Descending signal comes to the gamma motoneuron and changes sensitivity of muscle spindles to length.
  2. Spindle endings activity changes via the TSR and alters alpha motoneuron activity
  3. Level of muscle contraction changes, leading to changes in muscle length. Increase of contraction reulst in muscle shortening and a decrease in spindle activity.
  4. Movement continues until muscle length reaches a new value, at which muscle spindle activity causes a contraction which exactly balances the external load
A

Merton’s Servo hypothesis

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122
Q

The muscle will always reach a new equilibrium state

A

Merton’s Servo Hypothesis

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123
Q

A large change in external force is assumed to be perfectly compensated by the tonic stretch reflex mechanism - the mechanism has infinite gain.

A

Merton’s Servo Hypothesis

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124
Q

Merton’s model was proven to be

A

false

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125
Q

All voluntary movements do not begin with activation of gamma-motoneurons, but

A

with gamma and alpha motoneuron coactivation.

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126
Q

The gain in the tonic stretch reflex is

A

small to moderate.

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127
Q

The tonic stretch reflex cannot function as a length-control servo because

A

the gain is only small to moderate.

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128
Q

Central command theory

A

Central commands directly specify the activity levels of alpha motoneurons pools and therefore specify the levels of muscle activation.

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129
Q

Reflexes play a minor role, contributing mostly to unexpected changes.

A

Central command theory

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130
Q

Central commands use muscle reflexes to change the levels of muscle activity and specify parameters of these reflexes.

A

Equilibrium-point hypothesis

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131
Q
  1. Person tries to voluntarily activate the biceps brachii throughout the experiment.
  2. Load is removed, EMG activity drops off, even when person is still trying to activate muscle.
  3. Removing load greatly decreases the activity of the muscle spindles, so there is no reflexive recruitment of alpha motoneurons.
A

Unloading Reaction/Reflex

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132
Q

When a load is removed, a period of complete silence on the EMG follows even if the subject is trying to maintain activity

A

Unloading Reflex

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133
Q

According to the equilibrium point hypothesis, muscle reflexes specify a relation between muscle force and muscle length

A

An invariant characteristic

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134
Q

According to equilibrium-point hypothesis, the system is in equilibrium when

A

Muscular force is equal to external force.

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135
Q

In equilibrium point theory, if the external load changes,

A

muscular force and muscular length will change corresponding to a new equilibrium point

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136
Q

When muscle force is equal to external load in equilibrium point theory

A

Equilibrium point

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137
Q

A central command specifies the location of an invariant characteristic of the muscle (shifts the threshold of the tonic stretch reflex). A change in load can lead to a change in muscle length (isotonic), a change in muscle force (Isometric), and a change in both (elastic).

A

Equilibrium Point Hypothesis

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138
Q

What the subject is expected to do

A

Task parameters

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139
Q

What the subject actually does

A

Performance parameters

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140
Q

Triphasic EMG

A

Burst in agonist activity, followed by an antagonist burst, which is sometimes followed by a second agonist burst

141
Q

Reasons for triphasic EMG pattern

A

A quick burst of activity in the agonist muscle group activates the muscle spindles of the antagonist, leading to activation of alpha motoneurons of the antagonist.

142
Q

EMG peak amplitude, integrals over different time intervals

A

Magnitude

143
Q

Delay of the antagonist burst, duration of EMG bursts

A

Timing

144
Q

When load and distance are constant and velocity increases, 4 things happen

A
  1. An increase in the rate of agonist EMG rise, peak value, and area
  2. A decrease in the delay of the antagonist burst.
  3. An increase in the antagonist burst amplitude and area
  4. An increase in the level of final cocontraction.
145
Q

When load and velocity are constant and distance increases, 3 things happen

A
  1. Uniform rates of agonist EMG rise; higher and longer first agonist EMG burst
  2. Longer delays before the antagonist burst
  3. Inconsistent changes in the antagonist burst amplitude and duration.
146
Q

Load increases. Distance and velocity are constant. (5 things happen)

A
  1. Higher and longer agonist EMG bursts
  2. No changes in the rate of EMG rise
  3. Longer delay before the antagonist burst
  4. No apparent changes in the antagonist burst characteristics
  5. Increased final cocontraction
147
Q

2 types of isometric contractions

A

Step contractions

Pulse contractions

148
Q

Step contraction

A

The participant increases joint torque to a certain level.

149
Q

Pulse contraction

A

The participant increases joint torque to a certain level and then quickly relax.

150
Q

Control over movement duration at different speeds

A

Speed-sensitive

151
Q

No control over movement duration at the same speed

A

Speed-insensitive

152
Q

CNS computes “excitation pulses” to motoneural pools.

A

Dual Strategy Hypothesis

153
Q

EMGs are consequences of

A

both central commands and reflex loops

154
Q

If a movement is perturbed, EMGs are expected to change at a short reflex delay; changes in commands are expected

A

to come later.

155
Q

Early EMG changes are defined by

A

changes in muscle length

156
Q

Are not always reliable indices of central control signals

A

EMG

157
Q

Semi-automatic reactions to changes in muscle length, or other stimuli, that may be tentatively termed reflexes

A

Pre-programmed reactions

158
Q

Bridge between reflexes and voluntary action

A

Pre-programmed reactions

159
Q

Pre-programmed reactions are dependent on

A

Instructions

160
Q

Also called triggered reactions, M2-M3, functional stretch reflex, transcortical reflex, long-loop reflex

A

Pre-programmed reactions

161
Q

The latency of pre-programmed reactions

A

40-100 ms

162
Q

Are involuntary in nature but can be modified by instruction

A

Pre-programmed reactions

163
Q

Can be triggered by stimuli of virtually any modality

A

Pre-programmed reactions

164
Q

Generate a quick, crude compensation for the perturbation and are followed by a voluntary correction

A

Pre-programmed reactions

165
Q

Pre-programmed reactions can be stimulated by

A

proprioceptors, a flash of light, a loud tone, etc.

166
Q

Perturbations during a fast voluntary movement, EMG changes for pre-programmed reactions will generally

A

increase the activity of the muscle acting against the perturbation and decrease the activity of the muscle acting with the perturbation.

167
Q

3 things that can affect pre-programmed reactions

A

experience, instructions, and predictability

168
Q

Pre-programmed reactions are triggered in response to

A

unexpected loading or unloading of effectors

169
Q

The execution of any motor task is associated with

A

pre-programming of compensatory reactions to conceivable perturbations

170
Q

5 examples of pre-programmed reactions

A
  1. The “waiter’s response:
  2. Grasp adjustments
  3. Two-hand object holding
  4. Reactions to postural perturbations (ankle and hip strategies)
  5. Corrective stumbling reaction
171
Q

The amplitude of the pre-programmed response is determined

A

before the perturbation

172
Q

Subjects can pre-program

A

any combinations of command functions to any muscle or muscle group

173
Q

Pre-programmed reactions for posture

A

Corrective postural reactions

174
Q

Pre-programmed postural corrections to a perturbation are dependent on

A

Context

175
Q

A group of reactions to external stimuli that come at a longer latency than reflexes but shorter than voluntary reactions

A

Pre-programmed reactions

176
Q

Can be modulated by prior instruction or experience or predictability

A

Pre-programmed reactions

177
Q

Produce quick, crude corrective actions that counteract the mechanical effects of perturbation

A

Pre-programmed reactions

178
Q

Can be seen in muscles whose length is increased, decreased, or unchanged by the perturbation

A

Pre-programmed reactions

179
Q

Exact source of sensory information is not important as long as it carries sufficient information

A

Pre-programmed reactions

180
Q

Are a very important component of postural control and locomotion

A

Pre-programmed reactions

181
Q

Consists of the spinal cord and brain.

A

Central nervous system

182
Q

Borders with the medulla

A

The spinal cord

183
Q

Autonomic function

A

Medulla

184
Q

Contains important nuclei (cardiac, vasomotor, and respiratory center)

A

Medulla

185
Q

Located between the medulla and the midbrain

A

The pons

186
Q

Contains both ascending and descending white fiber tracts and several nuclei including the cranial nerves V to VIII.

A

The pons

187
Q

Lies behind the medulla and the pons. Consists of two hemispheres and a central area (vermis)

A

Cerebellum

188
Q

Is supported by three peduncles

A

Cerebellum

189
Q

Helps with timing of movements, balance, posture, coordination, and possibly assembling of motor synergies

A

Cerebellum

190
Q

Contains four elevations called colliculi, which are divided into two superior colliculi (vision and occular reflexes) and two inferior colliculi (processing of auditory information)

A

The midbrain

191
Q

A typical feature of cerebellar disorders

A

Dis-coordination or ataxia

192
Q

The two major nuclei contained in the midbrain

A

The red nucleus

The substantia nigra

193
Q

Important for voluntary movement

A

The red nucleus

194
Q

Motor control

A

Substantia nigra

195
Q

Is almost completely surrounded by cerebral hemispheres

A

The diencephalon

196
Q

Contains the thalamus, hypothalamus, the hypophysis, and the epiphysis

A

Diencephalon

197
Q

Integration of sensory and motor information

A

Thalamus

198
Q

aids in autonomic functions

A

Hypothalamus

199
Q

The pineal gland

A

Epiphysis

200
Q

Includes the hypothalamus, the fornix, the hippocampus, the amygdaloid nucleus, and the cingulate gyrus of the cerebral cortex

A

The limbic system

201
Q

Short term memory and memory consolidation

A

Hippocampus

202
Q

Connects the two hemispheres in the cerebrum

A

The corpus callosum and the anterior commissure

203
Q

The five lobes of the cerebrum

A 
Frontal lobe
Parietal lobe
Occipital lobe
Temporal lobe
Insula
204
Q

Involved heavily in voluntary movements, coordination, and perception

A

The cerebrum

205
Q

Consists of the globulus pallidus, putamen, caudate nucleus, subthalamic nucleus, and substantia nigra

A

Basal ganglia

206
Q

Plays an important role in the initiation of voluntary movements

A

Basal Ganglia

207
Q

Control of neck and face

A

Nuclei of the cranial nerves

208
Q

Stimulation can induce locomotion

A

Reticular formation

209
Q

Synergy formation, timing, memory, motor learning

A

Cerebellum

210
Q

Source of a major descending pathway

A

Red nucleus

211
Q

Sensorimotor integration

A

Thalamus

212
Q

Emotions

A

Limbic circle

213
Q

Motor control, movement initiation

A

Basal ganglia

214
Q

“Higher” functions, motor control

A

Cortex of large hemispheres

215
Q

Method to study the collective electrical activity of a large group of neurons

A

Electroencephalography (EEG)

216
Q

EEG waves seen during consciousness

A

Alpha and Beta waves

217
Q

EEG wave seen during rest or sleep

A

Delta and Theta waves

218
Q

Allows for high temporal resolution (Changes in brain activity from millisecond to millisecond)

A

EEG

219
Q

Very poor spatial resolution

A

EEG

220
Q

Difficult to identify the exact source of the

A

electrical signal

221
Q

Can be recorded from the back in response to an electrical stimulation of a peripheral nerve

A

Evoked potentials in the spinal cord

222
Q

Identifies objects with different X-ray absorption

A

Radiography

223
Q

Typically correlates with density

A

Radiography

224
Q

High spatial resolution

A

Radiography

225
Q

Detects changes in blood vessels (stroke, aneurysms)

A

Angiography

226
Q

Creates a 3-D image based on radiography, short examination time

A

Computer Tomography (CT)

227
Q

Relatively high resolution

A

CT

228
Q

Can visualize white and gray matter

A

CT

229
Q

Useful for looking at blood vessels in the brain

A

CT

230
Q

Measures the concentration of radioactive tracers

A

Positron Emission Tomography (PET)

231
Q

Selective sensitivity to different substances and processes

A

PET

232
Q

Useful for detecting brain patterns that occur over longer periods of time

A

PET

233
Q

Radio-frequency pulse perturbs protons, which release energy that can be analyzed

A

Magnetic Resonance Imaging (MRI)

234
Q

Very high degree of contrast of different matter; no bone artifact

A

MRI

235
Q

Requires high degree of cooperation from the patient

A

MRI

236
Q

Has problems with metal objects

A

MRI

237
Q

Superior ability to differentiate tissues

A

MRI

238
Q

Good spatial, poor temporal resolution

A

MRI

239
Q

Comparing MRI measurements obtained before and after performing a task

A

Functional MRI

240
Q

Can show changes in the signal in different brain structures during natural tasks

A

Functional MRI

241
Q

Very poor time resolution (need to wait several seconds or minutes between task)

A

Functional MRI

242
Q

Questionable interpretation of the BOLD response

A

Functional MRI

243
Q

Has a multilayer structure

A

Cerebral cortex

244
Q

2 types of cells contained in the cerebral cortex

A

Pyramidal cells

Stellate cells

245
Q

Interprets sensory data

A

Cerebral Cortex

246
Q

Provides perception of sensory data

A

Cerebral Cortex

247
Q

Makes conscious decisions

A

Cerebral Cortex

248
Q

Is active in voluntary movement

A

Cerebral cortex

249
Q

Aids in the planning, execution, and accuracy of movements

A

Cerebral cortex

250
Q

Most knowledge of the function of these structures comes from studies of individuals with brain injury

A

Cortex and cerebellum

251
Q

This hemisphere of the brain is dominant in 96% of right handed people

A

Left hemisphere

252
Q

This hemisphere of the brain is dominant in 70% of left handed people

A

Left hemisphere

253
Q

This has been linked to the dominant hemisphere of the brain

A

Speech

254
Q

First layer of the cerebral cortex

A

Molecular: Contains axons and dendrites

255
Q

Second layer of the cerebral cortex

A

External granular: contains small pyramidal and stellate cells

256
Q

Third layer of the cerebral cortex

A

The internal granular: contains stellate and pyramidal cells

257
Q

Fourth layer of the cerebral cortex

A

Ganglionic: Large pyramidal cells

258
Q

Fifth layer of the cerebral cortex

A

Multiform: Many different neurons which communicate within and leave the cortex

259
Q

How many layers are in the cerebral cortex?

A

5

260
Q

These cells in the cerebral cortex project to other neurons in the same cortical area and well as in other cortical areas

A

Pyramidal cells of layers II and III

261
Q

Intracortical communication

A

When a pyramidal cell in one cortical area communicates with cells in another coritcal area

262
Q

Most input from the cortex comes from the

A

Thalamus

263
Q

Acts as a relay station, processing information from the peripheral afferents, the cerebellum, and the basal ganglia

A

Thalamus

264
Q

Thalamic inputs make synapses in

A

Layer IV with the stellate cells

265
Q

Stellate cells synapse with

A

Pyramidal cells

266
Q

Pyramidal cells receive sensory information from

A

The thalamus and the cortex

267
Q

Brodmann divided the cerebral cortex into over

A

50 areas

268
Q

These cerebral cortex areas are important for the control of movements

A

Areas 4 and 6

269
Q

Area 4 is also known as the

A

Primary motor area

270
Q

This area of the cortex is active during movement

A

Primary motor area

271
Q

This is an upper motor neuron syndrome

A

Amyotrophic lateral sclerosis (ALS), a.k.a.: Lou Gehrig’s disease

272
Q

Contains giant output cells, particularly in zones with projections to leg muscles

A

Primary motor area

273
Q

Has a motor map of the body (somatotopic organization)

A

Primary motor area

274
Q

Active during execution of voluntary movements

A

Primary motor area

275
Q

Damage can cause paralysis and spasticity (upper motor neuron disorder)

A

Primary motor area

276
Q

Area 6 of the cerebral cortex is also known as the

A

Premotor area

277
Q

Is active during movement planning

A

Premotor area

278
Q

More complex movements originate here

A

Premotor area

279
Q

Hand and mouth movements start here

A

Premotor cortex

280
Q

Goal directed actions such as grasping start here

A

Premotor cortex

281
Q

Involved in the planning, generation, and control of sequential motor actions and contextual control

A

Premotor cortex

282
Q

Impaired restraint of potential motor acts elicited by objects

A

Premotor cortex

283
Q

Motor execution

A

Primary motor area

284
Q

Motor preparation and planning

A

Supplementary motor area

285
Q

Interprets clues or goal directed movements

A

Premotor area

286
Q

Proprioceptive information, speech, verbal expression

A

Parietal lobes

287
Q

Inputs to the motor cortex come from the

A

spinal cord, basal ganglia, and cerebellum

288
Q

Inputs to the motor cortex are mediated by the

A

ventrobasal nuclei of the thalamus

289
Q

Outputs of the motor cortex include projections to

A

basal ganglia, cerebellum (via pons), red nucleus, and reticular formation and spinal cord

290
Q

Corticospinal tracts decussate at the level of the

A

Medulla

291
Q

Stimulating different cortical cells may activate the same group of motor units and result in similar movements

A

Convergence

292
Q

Stimulating one cortical cell can activate different groups of motor units and move different body parts

A

Divergence

293
Q

Medial area of the cerebellum

A

Vermis

294
Q

Has two hemispheres and a medial area

A

Cerebellum

295
Q

The cerebellum is connected to other neural structures by

A

3 pairs of peduncles

296
Q

Cerebellum makes up this much of brain volume

A

10%

297
Q

How many neurons in the brain does the cerebellum contain?

A

More than half

298
Q

Ratio of inputs to outputs in the cerebellum

A

40:1

299
Q

Number of lobes of the cerebellum

A

3

300
Q

Disorders of the cerebellum result in

A

Disruptions of normal movement

301
Q

Is different than the paralysis caused by cerebral cortex damage

A

Cerebellum disorders

302
Q

4 common symptoms of cerebellum disorders

A

Hypotonia
Astasia-abasia
Ataxia
Tremors

303
Q

Hypotonia definition

A

Diminished resistance to passive limb displacements

304
Q

Astasia-abasia

A

Inability to stand or walk

305
Q

Abasia

A

Loss of the ability to maintain an upright stance against gravity

306
Q

Astasia

A

Loss of the ability to maintain a steady limb or body posture across multiple joints

307
Q

Ataxia

A

lack of coordination

308
Q

When are tremors observed in cerebellum disorders?

A

Tremors are seen at the of movements or when attempting to stop (action or intention tremor)

309
Q

How many types of neurons are in the cerebellum?

A

5 types

310
Q

The 5 types of neurons in the cerebellum

A 
Granule cells
Golgi cells
Stellate cells
Basket cells
Purkinje cells
311
Q

Axons are called parallel fibers

Excitatory to all cells below it

A

Granule cells

312
Q

Excited by parallel fibers, inhibit granule cells

A

Golgi cells

313
Q

Interneurons are within the cerebellum
Inhibits Purkinje cells
Controls the flow of output information

A

Stellate cells and basket cells

314
Q

Only output of the cerebellum, inhibitory neurons

A

Purkinje cells

315
Q

Timing, learning, memory, and modeling of motor actions happens in the

A

Cerebellar neurons

316
Q

Excitatory inputs in the cerebellum are provided by

A

Mossy fibers and climbing fibers

317
Q

make synapses on the Purkinje cells

A

Climbing fibers

318
Q

Excites Granule cells

A

Mossy fibers

319
Q

Granule cells (parallel fibers) send excitatory impulses to

A

Purkinje cells, basket cells, stellate cells, and golgi cells

320
Q

Stelate cells make inhibitory synapses on

A

Purkinje cells

321
Q

Basket cells inhibit

A

Purkinje cells

322
Q

Golgi cells inhibit

A

Granular cells

323
Q

Modulate the activity of the Purkinje cells

A

Stellate, basket, and Golgi cells

324
Q

Purkinje fibers send output signal from the cerebellum. They innervate

A

the reticular formation, ventrolateral (cerebellar) thalmus, and the red nucleus.

325
Q

Most information from the cerebellar thalamus projects to

A

areas 4 and 6 of the cerebral cortex

326
Q

Removal of the cerebellum or lesions on the cerebellum can lead to major problems with

A

eye movements, balance, posture, and coordination

327
Q

Helps with timing of actions

A

Cerebellum

328
Q

Assembles motor synergies

A

Cerebellum

329
Q

Compares intended action to actual action (acts as a comparator)

A

Cerebellum

330
Q

Diseases of the basal ganglia

A

Parkinson’s and Huntingdon’s

331
Q

5 Structures of the basal ganglia

A 
Caudate nucleus
Putamen
Globulus pallidus
Subthalamic nucleus
Substantia nigra
332
Q

Its importance for voluntary control has been inferred from clinical observations

A

Basal ganglia

333
Q

Disorders can cause excessive involuntary movements, movement poverty, and slowness; all typically without paralysis

A

Disorders of the basal ganglia

334
Q

Sites of almost all afferent inputs to the basal ganglia

A

Caudate nucleus and putamen (striatum)

335
Q

Input to the basal ganglia comes from the

A

different areas of the cerebral cortex and nuclei of the thalamus

336
Q

Projections from the cortex onto the internal globulus pallidus and substantia nigra. Project directly onto thalamus and back to cerebral cortex

A

Direct pathway

337
Q

Projections from the cortex onto the external globulus pallidus, then to the subthalamic nuclei

A

Indirect pathway

338
Q

Has a net excitatory effect on cortical neurons

A

Direct pathway

339
Q

Has a net inhibitory effect on cortical neurons

A

Indirect pathway

340
Q

Believed to play a major role in the control of limb movements

A

Direct pathway

341
Q

Believed to play a role in oculomotor control

A

Indirect pathway

342
Q

Disinhibits areas of the motor system and thus allows movement to occur (not well supported)

A

Basal Ganglia

343
Q

Turns off postural activity and allows voluntary movement to occur (Not well supported)

A

Basal ganglia

344
Q

Are involved in sequencing and initiating voluntary movements

A

Basal ganglia

345
Q

Force control, controlling the antagonist muscle group

A

Basal ganglia

346
Q

Helps prevent unwanted movements

A

Basal ganglia

347
Q

Reciprocal inhibition is what type of reflex

A

Oligosynaptic

348
Q

Typical latency o the H-reflex and T-reflex

A

35 ms

349
Q

These receptors are involved in polysynaptic reflexes

A

Spindle endings, golgi tendon organs, articular receptors

EP 4703: Neural Control Of Human Movement (4 decks)

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