Chapter 19 Flashcards
Muscles are often arranged in opposing pairs, called ?
agonist and the antagonist.
The ____ ____ in vertebrate limb is a spinal reflex in which a muscle spindle causes ____ muscle contraction and ___ muscle relaxation, exemplifying the principle of reciprocity.
stretch reflex,extensor,flexor
The ____ ____ in vertebrate limb withdraws limb from
painful stimulus and ___ the contralateral limb.
flexion reflex,extends
Muscle spindles permit automatic load compensation without involving ____ ____ centers
higher brain
The simplest reflexes have large numbers of ____ involved.
neurons
For voluntary movement—____ _____—the primary input to muscles is from CNS, secondary input is from sensory neurons.
directed action
___ ____ are amenable to study because they
are repetitive sequences of predictable movement.
Rhythmic behaviors
Neural generation of rhythmic behavior
Two models: ____ control versus ____ control
peripheral, central
Central control, as in locust flight, relies on a ?
central pattern generator (CPG)
Sensory input modifies ____ ___ patterns.
centrally generated
Types of CPGs:
cellular oscillators, network oscillators,
hybrid oscillators
Two models of how rhythmic behaviors are produced:
peripheral control versus central control.
T/F: Locust flight has features of both.
Peripheral control fine tunes and entrains the CPG
T
A hybrid oscillator has features of both____ and ____
oscillators, as shown by the crab stomach, which strains food particles.
cellular and network
oscillators
Planning and execution of motor tasks involve
separate, adjacent areas of cerebral ___ ___.
motor cortex
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 _______.
association; motor cortex; basal ganglia
Which of the following statements about a network oscillator is true?
a. One or more neurons receive input that turns the network on, and then neurons interact to generate a rhythmic output pattern.
b. A pacemaker cell outside of the network turns the network on and off to control other effectors such as muscle fibers.
c. Each cell in the network has pacemaker properties that determine the rate of output from the network.
d. The cells in the network depolarize in response to input from sensory afferents.
e. Membrane potentials of the neurons in the network increase and decrease simultaneously.
A
Invertebrates have often been used in motor control studies because
only a few neurons are often involved in a particular step in an invertebrate motor control pathway.
In vertebrates, the highest-level planning of voluntary movement, such as deciding whether or not to make a movement, begins in the
association cortex.
Which of the following illustrates the principle of convergence?
a. A single muscle spindle afferent stimulates a single spinal motor neuron.
b. A single pain receptor afferent stimulates a single spinal interneuron.
c. Each motor neuron receives input from thousands of synapses.
d. A single muscle spindle afferent stimulates many motor neurons.
e. Each motor neuron receives input that has passed through multiple synapses on its way from the CNS.
c
neurons in the primary motor cortex that send output to activate spinal motor neurons, what type of cell?
Pyramidal cells
Compared to the repetitive motor patterns of locomotion, more complex motor behaviors
may be composed of simple patterns linked by CNS commands and responses to sensory feedback.
Experiments in which sensory afferent fibers in the hindlimbs of cats are transected show that sensory feedback from the limbs
is not necessary to maintain repetitive movements.
Studies of the circuitry and function of the vertebrate cerebellum have resulted in
several competing models of how the cerebellum might work to coordinate movement.
The Purkinje cells of the cerebellum send _______ output from the cerebellar cortex to _______.
inhibitory; the cerebellar nuclei
If you accidentally grab a very hot frying pan with your right hand, _______ will _______ action potential frequency.
α motor neurons innervating the right elbow flexors; increase
Voluntary movements of a vertebrate animal are generated by
interactions of several regions.
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?
a. Afferent neurons from the intrafusal fibers in the biceps brachii will increase their action potential frequency.
b. The action potential frequency in the α motor neurons to the biceps brachii will be increased reflexively.
c. The action potential frequency in the α motor neurons to the biceps brachii will be decreased reflexively.
d. The action potential frequency in the γ motor neurons to the biceps brachii will be increased reflexively.
e. The action potential frequency in the γ motor neurons to the biceps brachii will be decreased reflexively.
c
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?
Basal ganglia
The 1a afferent fibers associated with muscle spindles increase their action potential frequency only when the muscle
lengthens involuntarily or shortens less than expected during a voluntary contraction.
When your family physician taps your left patellar tendon with a mallet, stretch is sensed by sensory receptors
associated with intrafusal fibers in the quadriceps.
Modeling experiments on walking and swimming in robotic salamanders have yielded which of the following conclusions?
Walking or swimming movements can be generated automatically by a network of central pattern generators responding to the intensity of the central command.
Which of the following experimental results would demonstrate most strongly that sensory feedback is important in the control of rhythmic movement?
a. A decerebrate cat (in which a portion of the brain has been removed) can walk and run on a treadmill.
b. A decerebrate cat (in which a portion of the brain has been removed) is incapable of walking or running on a treadmill.
c. An insect in which sensory afferents from the wings have been cut can fly.
d. Repetitive stimulation of sensory afferents can alter the frequency of wingbeats in a tethered insect.
e. Repetitive stimulation of sensory afferents cannot alter the frequency of wingbeats in a tethered insect.
D
How does the indirect pathway of synaptic transmission in the basal ganglia help to fine tune voluntary movement?
a. The indirect pathway sends the signals that activate thalamic neurons associated with the intended movement.
b. The indirect pathway inhibits thalamic neurons, thereby suppressing movements that may compete with the intended movement.
c. The indirect pathway inhibits thalamic neurons, thereby modulating muscular force so that movements are not too forceful.
d. The indirect pathway reinforces the direct pathway so that thalamic neurons stimulate the motor cortex at higher frequency.
e. The indirect pathway excites thalamic neurons whereas the direct pathway excites spinal motor neurons directly.
B
Which of the following statements about the stomatogastric ganglion of a crayfish (which functions as a hybrid oscillator) is true?
a. The central nervous system sends output that depolarizes each cell in the ganglion simultaneously.
b. The central nervous system sends a depolarizing signal that begins each wave of depolarization.
c. A rhythm generated by a cellular oscillator is reinforced and stabilized by network properties.
d. A cellular oscillator generates rhythmic output under the control of a network of ganglionic cells.
e. The rate of stomatogastric ganglion output is completely independent of the CNS.
C
____ ____ between brain areas are common in
motor control (and other functions), a complex form of
feedback.
Looping circuits
Lifting a heavy weight causes an error signal in ___fibers.
1a
T/F: Lifting a light weight causes no 1a neuron activity.
T
innervate extrafusal fibers.
Alpha motor neurons
innervate intrafusal fibers of the muscle spindles.
Gamma motor neurons
1a sensory neurons excited from ______ and_____, exciting or inhibiting them.
muscle spindles and innervate motor neurons
A “no brainer” because the entire reflex is spinal, both
flexion of the stimulated limb and extension of the contralateral limb.
The flexion reflex
Vertebrate spinal reflexes are relatively simple,
well-understood neural circuits. 1a sensory neuron excites extensor motor neuron, Flexor is inhibited via inhibitory interneuron in spinal cord. 300 motor
neurons with 10,000 synapses each.
The stretch reflex
A vertebrate spinal reflex in which muscle stretching activates a muscle spindle stretch receptor, generating nerve impulses in 1a afferent axons that excite motor neurons innervating the same muscle to oppose the stretch.
stretch reflex
A small ganglion containing 30 or more neurons that controls rhythmic activity of stomach muscles in crustaceans. The ___ ___ is a model system for study of central pattern generators.
stomatogastric ganglion
A simple, relatively stereotyped, but graded behavioral response to a specific stimulus.
reflex
A principle of motor control in which signals that activate motor neurons and muscles also inhibit activation of antagonist motor neurons and muscles.
reciprocity
A neural circuit that acts as a central pattern generator as a result of the synaptic interaction of its constituent neurons, rather than as a result of oscillator activity in single cells.
network oscillator
Spreading apart. In neurophysiology, a pattern in which signals from a particular presynaptic neuron synaptically excite or inhibit many postsynaptic neurons.
divergence
Coming together. In neurophysiology, a pattern in which signals from many presynaptic neurons come together to affect a particular postsynaptic neuron.
convergence
A prominent structure of the vertebrate hindbrain, concerned with motor coordination, posture, and balance. Consists of the cerebellar cortex and deep cerebellar nuclei.
cerebellum
The outer layer of the cerebellum of the vertebrate hindbrain; involved in motor coordination and learning.
cerebellar cortex
A neuron that can generate a rhythmic change in membrane potential or activity without needing synaptic input to do so; one possible basis of a central pattern generator.
cellular oscillator
In the vertebrate brain, a collection of cell groups in the ventral forebrain that organize motor behavior. The caudate nucleus, putamen, and globus pallidus are major components of the basal ganglia; the subthalamic nucleus and substantia nigra (midbrain) are usually included.
basal ganglia
