* not completed

. Invertebrates have often been used in motor control studies because

invertebrates have many more motor neurons in a single pathway compared to vertebrates. correct incorrect

individual neurons are simpler in invertebrates than in vertebrates, and therefore motor control pathways are also simpler. correct incorrect

motor control pathways in invertebrates are all reflex pathways and therefore are simpler than pathways in vertebrates. correct incorrect

often only a few neurons are involved in a particular step in an invertebrate motor control pathway. correct incorrect

* not completed

. The 1a afferent fibers associated with muscle spindles increase their action potential frequency only when the muscle

shortens more than expected during a voluntary contraction. correct incorrect

shortens involuntarily or shortens more than expected during a voluntary contraction. correct incorrect

lengthens involuntarily or shortens less than expected during a voluntary contraction. correct incorrect

lengthens involuntarily. correct incorrect

* not completed

. When your family physician taps your left patellar tendon with a mallet, stretch is sensed by sensory receptors associated with

extrafusal fibers in the patellar tendon. correct incorrect

intrafusal fibers in the patellar tendon. correct incorrect

extrafusal fibers in the quadriceps. correct incorrect

intrafusal fibers in the quadriceps. correct incorrect

* not completed

. Which statement illustrates the principle of convergence?

A single muscle spindle afferent stimulates a single spinal motor neuron. correct incorrect

A single pain receptor afferent stimulates a single spinal interneuron. correct incorrect

Each motor neuron receives input from thousands of synapses. correct incorrect

A single muscle spindle afferent stimulates many motor neurons. correct incorrect

* not completed

. If you accidentally grab a very hot frying pan with your right hand, _______ will _______ action potential frequency.

α motor neurons innervating the left elbow extensors; decrease correct incorrect

α motor neurons innervating the right elbow flexors; increase correct incorrect

afferent neurons from the Golgi tendon organ in the right elbow extensors; increase correct incorrect

afferent neurons from the intrafusal fibers of the right elbow flexors; increase correct incorrect

* not completed

. Suppose that you contract your biceps brachii muscle to toss a juggling pin into the air and find that it is much lighter than you expected. Which of the following will happen in compensation?

The action potential frequency in the α motor neurons to the biceps brachii will be decreased reflexively. correct incorrect

The action potential frequency in the α motor neurons to the biceps brachii will be increased reflexively. correct incorrect

The action potential frequency in the γ motor neurons to the biceps brachii will be increased reflexively. correct incorrect

The action potential frequency in the γ motor neurons to the biceps brachii will be decreased reflexively. correct incorrect

* not completed

. Which experimental result would demonstrate most strongly that sensory feedback is important in the control of rhythmic movement?

A cat whose cerebral cortex has been removed can still walk and run on a treadmill. correct incorrect

An insect in which sensory afferents from the wings have been cut can still fly. correct incorrect

Repetitive stimulation of sensory afferents alters the frequency of wingbeats in a tethered insect. correct incorrect

Repetitive stimulation of sensory afferents does not alter the frequency of wingbeats in a tethered insect. correct incorrect

* not completed

. Which statement about a network oscillator is true?

One or more neurons receive input that turns the network on, and then neurons interact to generate a rhythmic output pattern. correct incorrect

A pacemaker cell outside of the network turns the network on and off to control other effectors such as muscle fibers. correct incorrect

Each cell in the network has pacemaker properties that determine the rate of output from the network. correct incorrect

The cells in the network depolarize in response to input from sensory afferents. correct incorrect

* not completed

. Which statement about the stomatogastric ganglion of a crayfish is true?

The central nervous system sends output that depolarizes each cell in the ganglion simultaneously. correct incorrect

The central nervous system sends a depolarizing signal that begins each wave of depolarization. correct incorrect

A rhythm generated by a cellular oscillator is reinforced and stabilized by network properties. correct incorrect

A cellular oscillator generates rhythmic output under the control of a network of ganglionic cells. correct incorrect

* not completed

. Compared to the repetitive motor patterns of locomotion, more complex motor behaviors

probably involve many more spinal motor neurons in each step. correct incorrect

probably rely on mechanisms that are completely different from those involved in locomotion. correct incorrect

may be composed of simple patterns linked by CNS commands and responses to sensory feedback. correct incorrect

involve similar patterns within the CNS but different output pathways to the skeletal muscles. correct incorrect

* not completed

. Experiments in which sensory afferent fibers in the hindlimbs of cats are transected show that sensory feedback from the limbs

is necessary to maintain repetitive movements. correct incorrect

is not necessary to maintain repetitive movements. correct incorrect

is necessary to initiate locomotor movements. correct incorrect

normally acts to inhibit limb muscle contractions. correct incorrect

* not completed

. Modeling experiments on walking and swimming in robotic salamanders have concluded that walking and swimming

are completely distinct motor patterns involving separate central pattern generators. correct incorrect

use the same central pattern generator and timing, but the output goes to different muscle groups for each mode of locomotion. correct incorrect

movements can be generated automatically by a network of central pattern generators responding to the intensity of the central command. correct incorrect

movements are generated from a single central pattern generator responding to the sensory feedback received by the salamander. correct incorrect

* not completed

. Pyramidal cells are

neurons in the primary motor cortex that send output to activate spinal motor neurons. correct incorrect

neurons in the cerebellum that send the sole output from the cerebellar cortex. correct incorrect

neurons in the cerebellum that exert excitatory effects on other cerebellar neurons. correct incorrect

sensory neurons that collect information on joint position and muscle length. correct incorrect

* not completed

. In vertebrates, the highest-level planning of voluntary movement, such as deciding whether or not to make a movement, begins in the

association cortex. correct incorrect

basal ganglia. correct incorrect

cerebellar cortex. correct incorrect

primary motor cortex. correct incorrect

* not completed

. The Purkinje cells of the cerebellum send _______ output from the cerebellar cortex to the _______.

excitatory; cerebellar nuclei correct incorrect

inhibitory; cerebellar nuclei correct incorrect

excitatory; spinal cord correct incorrect

inhibitory; spinal cord correct incorrect

* not completed

. Studies of the circuitry and function of the vertebrate cerebellum have resulted in

a detailed map of the representation of individual muscles in the cerebellar cortex, as well as functional details of how the neurons interact to coordinate movement. correct incorrect

a detailed map of the representation of individual muscles in the cerebellar cortex, although there is still some uncertainty about the function of the different neurons. correct incorrect

a detailed explanation of how different categories of neurons interact to coordinate movement, but no spatial map. correct incorrect

several competing models of how the cerebellum might work to coordinate movement. correct incorrect

* not completed

. Voluntary movements in a vertebrate animal are generated by

the motor cortex. correct incorrect

the cerebellum. correct incorrect

basal ganglia. correct incorrect

interactions of several regions. correct incorrect

* not completed

. How does the indirect pathway of synaptic transmission in the basal ganglia help to fine tune voluntary movement?

The indirect pathway sends the signals that activate thalamic neurons associated with the intended movement. correct incorrect

The indirect pathway inhibits thalamic neurons, thereby suppressing movements that may compete with the intended movement. correct incorrect

The indirect pathway inhibits thalamic neurons, thereby modulating muscular force so that movements are not too forceful. correct incorrect

The indirect pathway reinforces the direct pathway so that thalamic neurons stimulate the motor cortex at higher frequency. correct incorrect

* not completed

. According to the current general model describing planning and execution of a voluntary movement, decisions generated in the _______ cortex are passed to the _______ via the _______.

motor; association cortex; cerebellum correct incorrect

association; motor cortex; basal ganglia correct incorrect

association; cerebellum; basal ganglia correct incorrect

frontal; basal ganglia; motor cortex correct incorrect

* not completed

. A 52-year-old woman has difficulty initiating voluntary movements. She can clearly state what she intends to do, describe exactly how she would do it, and picture herself doing it easily. When she is able to begin the motion, she can complete it smoothly and accurately, but she has difficulty beginning the motion. If the difficulty arises from a defect in one particular area of the nervous system, which area is most likely to be involved?

Association cortex correct incorrect

Basal ganglia correct incorrect

Spinal motor neurons correct incorrect

Spinocerebellum correct incorrect