Deck 19: Control of Movement

Question 1

Choose the correct statement regarding salamanders.

A) Salamanders are split into 2 groups-swimmers and walkers.
B) Control of swimming is completely different from the control of walking.
C) Swimming behavior evolved from walking behavior.
D) The neural circuitry that controls and coordinates swimming behavior also controls walking behavior.

Answer 1

D

Question 2

Compared to the neural circuits responsible for reflexes of invertebrates, the circuits of vertebrates involve

A) many more steps in sequence.
B) fewer steps in sequence.
C) many more individual neurons to complete the same steps.
D) fewer individual neurons to complete the same steps.

Answer 2

C

Question 3

According to the principle of reciprocity, when a muscle is stimulated to contract, its

A) agonists and antagonists also contract.
B) agonists and antagonists relax.
C) agonists contract while its antagonists relax.
D) antagonists contract while its agonists relax.

Answer 3

C

Question 4

Agonists are

A) muscles that work together to generate a given motion.
B) muscles that extend a joint.
C) muscles that have opposing actions.
D) sensory fibers that detect pain in order to trigger protective reflexes.

Question 5

The muscle fibers in a muscle spindle

A) are not true muscle fibers because they cannot contract.
B) function to maintain tension on spindle stretch receptors.
C) are recruited only during very high force contractions.
D) are recruited only during very low force contraction.

Question 6

When your family physician taps your left patellar tendon with a mallet,

A) the intrafusal muscle fibers in your left quadriceps contract.
B) many motor neurons innervating your left quadriceps are excited by 1a afferent fibers.
C) a single motor neuron innervating your left quadriceps is excited by a 1a afferent fiber.
D) a single motor neuron innervating your left quadriceps is inhibited by a 1a afferent fiber.

Question 7

Your family physician taps your left patellar tendon with a mallet. What is the correct sequence of the events that occur?
I) Inhibition of motor neuron innervating flexors
II) Action potentials in 1a sensory neuron
III) Muscle spindle stretch receptor activated
IV) Action potentials in neuron innervating flexors
V) Action potentials in neuron innervating extensors

A) III → II → I and V simultaneously
B) II → III → IV
C) III → II → I → V
D) II → IV and V simultaneously → III

Question 8

When your family physician taps your left patellar tendon with a mallet, motor neurons innervating the flexors of the left knee are inhibited by _______ in the _______.

A) interneurons; spinal cord
B) interneurons; muscle
C) interneurons; tendon
D) sensory neurons; muscle

Question 9

In the stretch reflex, a signal from a sensory neuron that detects stretch in a muscle reaches a motor neuron innervating the stretched muscle via

A) excitatory interneurons in the brain.
B) a single excitatory synapse.
C) inhibitory interneurons in the spinal cord.
D) direct sensory-to-motor-neuron synapses as well as excitatory spinal interneurons.

Question 10

Which statement illustrates the principle of divergence?

A) A single muscle spindle afferent stimulates many motor neurons.
B) A single muscle spindle afferent stimulates a single spinal motor neuron.
C) Each motor neuron receives input from thousands of synapses.
D) Each motor neuron receives input that has passed through multiple synapses on its way from the CNS.

Question 11

When you step on a tack, excitation of sensory afferents leads to excitation of motor neurons innervating one set of muscles and inhibition of motor neurons innervating another set of muscles. The stimulus produces opposite responses in different motor neurons because

A) motor neurons innervating different muscles have different receptors.
B) the afferent neuron releases different neurotransmitters at different synapses.
C) the sensory afferents transmit both excitatory and inhibitory action potentials that are sent to different motor neurons.
D) the signals reach some motor neurons via excitatory interneurons but they reach other motor neurons via inhibitory interneurons.

Question 12

When you are walking barefoot and your left foot lands on a marble, the

A) flexors of your left leg relax.
B) flexors of your right leg contract.
C) extensors of your left leg contract.
D) extensors of your right leg contract.

Question 13

When you voluntarily pick up a glass of milk, your

A) α motor neurons stimulate extrafusal muscle fibers to contract, while γ motor neurons stimulate the ends of intrafusal muscle fibers to contract.
B) γ motor neurons stimulate extrafusal muscle fibers to contract, while α motor neurons stimulate the ends of intrafusal muscle fibers to contract.
C) α motor neurons stimulate extrafusal muscle fibers to contract, while γ motor neurons stimulate the ends of intrafusal muscle fibers to relax.
D) γ motor neurons stimulate extrafusal muscle fibers to contract, while α motor neurons stimulate the ends of intrafusal muscle fibers to relax.

Question 14

If only α motor neurons were activated during a voluntary movement, the muscle spindle would be unable to transmit information to correct the rate of the movement because the

A) extrafusal fibers would not shorten.
B) intrafusal fibers would be stretched excessively.
C) intrafusal fibers would be slack.
D) intrafusal fibers would remain at their resting length.

Question 15

Refer to the figure shown.
According to the figure, which numeral represents the sensory neuron?

A) I
B) II
C) III
D) IV

Question 16

Refer to the figure shown.
Which neuron in the figure is inhibitory?

A) II
B) III
C) IV
D) All neurons are excitatory.

Question 17

Refer to the figure shown.
Which numeral in the figure represents the 1a afferent pathway?

A) I
B) II
C) III
D) IV

Question 18

Refer to the figure shown.
The flexion-reflex afferent pathway originates with which neuron?

A) I
B) II
C) III
D) IV

Question 19

If you voluntarily lift an object and have correctly judged its weight,

A) the intrafusal muscle fibers shorten at a rate that maintains constant tension on the stretch receptor.
B) the muscle spindle afferents fire a rapid burst of action potentials.
C) α motor neurons fire action potentials but γ motor neurons do not.
D) γ motor neurons fire action potentials but α motor neurons do not.

Question 20

If you voluntarily lift an object and have underestimated its weight,

A) the intrafusal muscle fibers shorten at a rate that maintains constant tension on the stretch receptor.
B) the muscle spindle afferents fire a rapid burst of action potentials.
C) α motor neurons fire action potentials but γ motor neurons do not.
D) γ motor neurons fire action potentials but α motor neurons do not.

Question 21

If you voluntarily lift an object and have underestimated its weight,

A) a burst of action potentials from the muscle spindle afferents causes the contracting muscles to contract more forcefully.
B) a burst of action potentials from the muscle spindle afferents causes the contracting muscles to stop contracting.
C) the absence of action potentials from the muscle spindle afferents causes the contracting muscles to contract more forcefully.
D) the absence of action potentials from the muscle spindle afferents causes the contracting muscles to stop contracting.

Question 22

Refer to the figure shown.
Which caption best describes the figure?

A) Intrafusal fiber training
B) Response of intrafusal fibers to no load
C) Successful lengthening extrafusal fibers under load via coactivation
D) 1a activated contraction of extrafusal fibers to lift heavy load

Question 23

Refer to the figure shown.
Of the four numerals in the figure, which one best represents a reflex pathway?

A) I
B) II
C) III
D) IV

Question 24

In rhythmic behavior such as human walking, each muscle contraction occurs in response to

A) nerve action potentials originating in the CNS.
B) nerve action potentials originating in peripheral neurons.
C) stretch reflexes originating in the muscle.
D) spontaneous action potentials originating in muscle cells.

Question 25

According to the peripheral control model of insect flight,

A) sensory detection of wing depression stimulates motor neurons innervating the depressor muscles.
B) sensory detection of wing depression stimulates motor neurons innervating the levator muscles.
C) motor neurons stimulating the depressors also inhibit the levators.
D) sensory detection of wind causes the depressors to contract.

Question 26

Which experimental results would demonstrate that central pattern generators are involved in producing the muscle contractions involved in rhythmic movement?

A) A cat whose cerebral cortex has been removed can walk and run on a treadmill.
B) A cat whose cerebral cortex has been removed has impaired balance on a treadmill.
C) An insect in which the sensory afferents from the wings have been cut can fly.
D) An insect in which the sensory afferents from the wings have been cut has an unusually slow wingbeat frequency.

Question 27

How are central pattern generators and peripheral reflexes thought to interact in normal locomotion?

A) Peripheral reflexes initiate locomotion, and central pattern generators maintain it.
B) Central pattern generators initiate locomotion, and peripheral reflexes maintain it.
C) Central pattern generators control locomotion with no input from peripheral reflexes.
D) Central pattern generators initiate and maintain locomotion, and reflexes correct and fine-tune motion.

Question 28

A cellular oscillator in a central pattern generator is a cell

A) whose membrane potential responds to stimulation from other cells.
B) whose membrane potential goes through regular cycles of depolarization and repolarization.
C) whose membrane potential is unusually resistant to depolarization or hyperpolarization.
D) that fires action potentials.

Question 29

Refer to the figure shown.
In order to function effectively as an oscillatory network, the half-center model depicted in the figure must

A) include a cell that depolarizes spontaneously.
B) involve a mechanism for the activated neuron to stop signaling.
C) involve a mechanism for one of the neurons to start signaling first.
D) includes both excitatory and inhibitory synapses between the two neurons.

Question 30

Refer to the figure shown.
In the closed-loop network depicted in the figure, stimulation from outside the network would cause cell 3 to fire

A) an indefinite train of action potentials.
B) action potentials until it is inhibited by the CNS.
C) action potentials as long as it receives stimulation from the CNS.
D) action potentials until it is inhibited by cell 1.

Question 31

Oscillatory networks based on the half-center model are unstable unless

A) there is a fatigue mechanism so that the first neuron that fires action potentials stops firing action potentials.
B) there is a stabilizing mechanism that helps the first neuron that depolarizes to remain depolarized.
C) there is a stabilizing mechanism so that the first neuron that fires action potentials keeps firing action potentials.
D) there is a fatigue mechanism so that the external command stimulation stops.

Question 32

The stomatogastric ganglion of decapod crustaceans has received extensive study because

A) control of the crustacean stomach is very similar to control of the human stomach.
B) the stomatogastric ganglion is the simplest oscillator studied to date.
C) the stomatogastric ganglion generates a variety of rhythmic output with a small number of neurons.
D) the drugs that act on the stomatogastric ganglion are likely to have effects similar to those that act on the human digestive tract.

Question 33

Neuromodulators of the stomatogastric ganglion of a decapod crustacean would be least likely to have what action?

A) Change the order in which the neurons of the pyloric circuit contract
B) Speed up the rhythm of contractions in the stomach
C) Slow down the rhythm of contractions in the stomach
D) Alter the strength of muscle contractions in the stomach

Question 34

Refer to the figure shown.
Which statement is the most likely explanation for the data shown in the figure?

A) AB/PD is a cellular oscillator that activates PY, which activates LP.
B) AB/PD is a cellular oscillator that inhibits both LP and PY, which are autoactive.
C) PY is a cellular oscillator that activates both AB/PD and LP.
D) LP is a cellular oscillator that inhibits both AB/PD and PY.

Question 35

Refer to the figure shown.
If AB/PD fires first, which statement is true?

A) PY recovers the fastest and fires before LP
B) AB/PD activates firing of LP
C) LP and PY are activated and LP fires first
D) LP and PY are inhibited and LP recovers first and fires

Question 36

Refer to the figure shown.
The hybrid oscillator in the figure produces

A) a pyloric rhythm that controls the straining of food particles.
B) contractions that contract the gastric mill to grind food.
C) muscle contractions that contract vertebrate jaws.
D) an esophageal rhythm that controls food movement through the esophagus.

Question 37

The action potentials that directly trigger muscle contractions of walking movements in a vertebrate animal are initiated by neurons whose cell bodies are located in the

A) motor cortex.
B) cerebellar cortex.
C) basal ganglia.
D) spinal cord.

Question 38

Experiments in which cats with transected spinal cords are able to walk on treadmills demonstrate that the

A) brain does not normally initiate walking in cats.
B) brain does not control the timing of repetitive limb/wing movements in all animals.
C) brain does not control the timing of repetitive limb movements in cats.
D) spinal cord is not necessary for communication between the brain and the limbs.

Question 39

Injections of L-dopa, the precursor of norepinephrine, can enable spinally transected cats to walk on a treadmill. The most likely explanation for this result is that

A) norepinephrine stimulates spinal motor neurons, causing muscle contractions.
B) norepinephrine acts on the neuromuscular junctions of the limb muscles and causes muscle contractions.
C) norepinephrine activates sensory afferents that cause reflex muscle contractions in the limbs.
D) norepinephrine activates the central pattern generator that causes rhythmic stepping motions.

Question 40

Modeling experiments on walking and swimming in robotic salamanders suggest that

A) each type of repetitive motion that an animal performs is controlled by a distinct central pattern generator.
B) some repetitive motions are controlled by a central pattern generator, but others are not.
C) a particular central pattern generator always produces the same pattern of limb movements.
D) simple changes in the coordination of central pattern generators can produce different locomotor gait.

Question 41

In the network of central pattern generators that governs walking and swimming in salamanders,

A) movement is normally initiated by sensory input from the limbs.
B) oscillators on opposite sides of the body are coupled so that they are active at the same time.
C) stronger stimulation causes trunk oscillation to prevail over limb movements.
D) stronger stimulation increases the rate of movement and force of both trunk and limb muscles.

Question 42

In the primary motor cortex, the neurons most responsible for sending motor output to spinal motor neurons are the

A) mirror neurons.
B) pyramidal cells.
C) Purkinje cells.
D) granule cells.

Question 43

Output from the primary motor cortex consists mostly of action potentials that are transmitted to

A) synapses with interneurons in the spinal cord.
B) synapses with motor neurons in the brain.
C) synapses with motor neurons in the spinal cord.
D) the cerebellum.

Question 44

The primary motor cortex contains neurons that

A) make decisions about what movements to undertake.
B) encode the force and direction of movements.
C) correspond to individual muscles according to location in the cortex.
D) connect only to areas outside of the brain.

Question 45

Evidence for the role of the primary motor cortex comes from experiments that show that

A) activation of individual neurons of the motor cortex matches activation of individual muscles.
B) activation of individual neurons of the motor cortex matches activation of individual motor units.
C) activity of some neurons of the motor cortex correlates with the force or direction of a movement.
D) the number of motor cortex neurons that fire action potentials is linearly related to the force of the muscle contraction.

Question 46

Electrical recordings from human volunteers indicate that the decision to move a body part and the signals generating that movement arise from

A) one specific area of the motor cortex.
B) one specific area of the cerebellum.
C) one specific area of the spinal cord.
D) interactions of multiple cortical regions.

Question 47

A readiness potential is a(n)

A) localized electrical potential within the primary motor cortex that corresponds precisely to the intended movement.
B) broad wave of electrical activity in the cerebral cortex that precedes a voluntary movement.
C) graded depolarization of spinal motor neurons that makes it easier for them to reach threshold in response to sensory input.
D) electrical potential generated in the cerebellum in preparation for a voluntary movement.

Question 48

The frontal cortex contains areas that are involved in

A) receiving visual or auditory stimuli that might trigger a movement.
B) monitoring and correcting the accuracy of movement.
C) planning and organizing movement.
D) sending signals to muscle fibers.

Question 49

The main role of the cerebellum is to

A) make decisions on which voluntary movements to perform.
B) plan the sequence of muscle contractions involved in an involuntary movement.
C) send the signals to activate muscle fibers involved in a voluntary movement.
D) provide feedback to correct errors as a voluntary movement is performed.

Question 50

Output from the cerebellar cortex is sent by

A) Purkinje cells.
B) Golgi cells.
C) granule cells.
D) stellate cells.

Question 51

The involvement of the cerebellum in motor learning is demonstrated by the observation that patients with cerebellar lesions are

A) paralyzed on one side of their body.
B) paralyzed on both sides of their body.
C) capable of voluntary movements but are clumsy and uncoordinated.
D) capable of coordinated movement if they are helped with initiating the movement.

Question 52

The involvement of the cerebellum in preprogramming voluntary movements is demonstrated by the observation that many patients with cerebellar lesions are

A) paralyzed on one side of their body.
B) paralyzed on both sides of their body.
C) capable of coordinated movement if they are helped with initiating the movement.
D) capable of voluntary movements but must think about each step in complex movements individually.

Question 53

Most of the neurons in the basal ganglia are inhibitory. How can an inhibitory synapse be involved in generating a movement?

A) Inhibitory action potentials are converted to excitatory action potentials when they arrive at the neuromuscular junction.
B) Inhibition of a tonically active inhibitory neuron results in disinhibition of its target neuron.
C) Muscle fibers receive the inhibitory input and convert it into excitatory input.
D) Inhibiting other motor pathways automatically excites the relevant motor pathway.

Question 54

Excitatory inputs from the cerebral cortex to the striatum will lead to what effects on corresponding neurons downstream in the direct pathway of the basal ganglia?

A) Excitation in the globus pallidus and inhibition in the thalamus
B) Excitation in the globus pallidus and excitation in the thalamus
C) Inhibition in the globus pallidus and excitation in the thalamus
D) Inhibition in the globus pallidus and inhibition in the thalamus

Question 55

Which human pathology has been linked to degeneration of the basal ganglia?

A) Alzheimer's disease
B) Multiple sclerosis
C) Parkinson's disease
D) Retrograde amnesia

Question 56

Movement disorders such as Parkinson's disease and Huntington's disease are associated with degeneration in what areas of the central nervous system?

A) The frontal cortex
B) The primary motor cortex
C) Spinal motor neurons
D) The basal ganglia

Question 57

What experimental evidence indicates that the decision to perform a voluntary movement originates in the association cortex?

A) A localized electrical potential in the association cortex is the first electrical signal recorded prior to a motion.
B) Diffuse readiness potentials can be recorded over most of the cortical surface prior to the localized potentials that precede movement.
C) Lesions of specific locations in the association cortex correspond to deficits in movement of corresponding body parts.
D) Animals with superior motor coordination have significantly larger association cortices than other animals.

Question 58

The motor cortex sends output to the cerebellum as movements are initiated, and the cerebellum

A) transmits output from the motor cortex to the spinal motor neurons.
B) transmits output from the motor cortex to the muscle fibers.
C) compares sensory feedback to the initial motor output to detect errors.
D) generates the readiness potential that precedes movement.

Question 59

A 66-year-old man has difficulty controlling voluntary movements. He can clearly state what he intends to do, describe how he would do it, and initiate or stop the movement. However, he has poor coordination and often misses his target. If his difficulty arises from a defect in one particular area of the central nervous system, which area is most likely to be involved?

A) Association cortex
B) Primary motor cortex
C) Muscle spindles
D) Spinocerebellum

Question 60

Refer to the figure shown.
Joey is lying in bed motionless. Which neuron in this figure is tonically active?

A) I
B) II
C) III
D) IV

Question 61

Refer to the figure shown.
Beth knows the answer to a question and raises her hand. During the initiation of this movement, which neuron in the figure becomes disinhibited?

A) I
B) II
C) III
D) IV

Question 62

Write a paragraph describing the mechanism that causes you to withdraw your right hand very rapidly when you reach out and touch a hot frying pan by mistake.

Question 63

Explain why α‒γ coactivation is important for quality control of voluntary motions.

Question 64

Compare and contrast the central control hypothesis and peripheral control hypothesis as they relate to insect flight

Question 65

Draw a diagram of a network oscillator involving at least three neurons and label each synapse as excitatory or inhibitory. Graph the membrane potential of each neuron in the oscillator as a function of time on a single x-axis and write a paragraph describing how the network works and the pattern of output that it generates.

Question 66

Contrast the mechanisms by which cellular oscillators and network oscillators generate patterns of rhythmic motion.

Question 67

The phrase "like a chicken with its head cut off" refers to a person rushing around frantically or carelessly. Explain how a chicken might be able to run (briefly) after its brain has been disconnected from the rest of its body.

Question 68

In what ways do mirror neurons in the premotor areas of the cerebral cortex highlight the complexity of motor pathways?

Question 69

Sketch and give a written description of how the nervous system plans, programs, and executes a voluntary movement. Include a sentence describing the role of each of at least four different brain areas.

Question 70

Describe how observations of human patients or animals with lesions of the nervous system have contributed to our understanding of normal motor control. Include relevant examples and relate them to general experimental principles.

Question 71

Discuss some of the areas of scientific uncertainty regarding the control of voluntary movement by vertebrate animals. Speculate on some experimental techniques (either current or still to be developed) and possible experimental results that might help to refine our models of motor control.