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Kines 360 Exam IV
Terms in this set (61)
What are the two types of automatic spinal circuits?
Reflexes & Central Pattern Generators (CPGs)
In the stretch reflex, how many synapses are required for exciting the homonymous muscle?
In the stretch reflex, how many synapses are required to inhibit the antagonist muscle?
1. Ia sensory neuron and Ia inhibitory neuron
2. Ia inhibitory neuron and Alpha motor neuron
Inhibition of the antagonist occurs through the ______________ interneuron.
Is a first order sensory neuron always excitatory on its target?
YES (can inhibit, but is always excitatory first)
Can the stretch reflex be modified? What experiment showed reversal of the stretch reflex?
Yes; Lacquaniti showed this in the ball-catching experiment
Name the two components of the stretch reflex and the latency of each:
M1: 20-40 milliseconds
M2: 40-60 milliseconds
What effect does removal of the stretch reflex have on a stretched muscle?
The response becomes non-linear
Define muscle tone.
Resistance to passive movement in a muscle
This resistance is both displacement dependent (stiffness) and rate of change of displacement dependent (viscosity).
Is the stretch reflex necessary for normal muscle tone?
Describe the flexor withdrawal reflex
Noxious stimuli to the end of a limb (i.e. the foot) produces flexion of the ipsilateral limb and extension of the contralateral limb
Ex. Stepping on a nail
What is unique about the scratch reflex compared with other reflexes such as the flexor withdrawal reflex?
The scratch reflex persists for longer than the other stimulus is applied; The response is a continuous alternating movement of the leg.
What conditions are required for a spinalized cat which has been deafferented (no feedback from the limbs) to show walking patterns on a treadmill?
1. L-Dopa administration (or another drug that leads to norepinephrine release)
2. Trunk supported over a treadmill
Do humans have CPGs for walking?
Yes, it has been demonstrated by spinal cord patients who are administered L-Dopa as well as by infants.
A ______________________ is a cluster of motor neurons in the spinal cord that can span several segments and innervates a single muscle.
motor neuron pool
The ______________________ nucleus of the ventral horn sends information to the limb muscles.
The _____________________ nucleus of the ventral horn innervates axial muscles.
The ___________________ tract connects several segments to allow reflexes and central commands to act as a whole
The medial brainstem motor pathways include:
1. Lateral and medial vestibulospinal tracts
2. Pontine and medullary reticulospinal tracts
3. Colliculospinal tract (orienting to external stimuli)
The only lateral brainstem motor pathway is the ________________
The structure of origin for each of the medial brainstem tracts are:
1. Lateral and medial vestibular nuclei
2. Pontine and medullary reticular formation
3. The superior colliculus
The ________________________ tract is the only DESCENDING motor pathway to synapse with motor neurons in the ventrolateral nucleus of the ventral horn, innervating the distal extremities
(mediates aspects of motor control/fine motor control)
The lateral corticospinal tract originates from the neurons in what three cortical regions?
1. Primary somatosensory cortex
2. Primary motor cortex
3. Premotor cortex
The lateral corticospinal tract decussates in what structures?
Does the anterior corticospinal tract decussate?
The _______________ corticospinal tract innervates the medial brainstem pathways
An _______________________________ occurs before movement to prevent the movement from disturbing posture. For example, when pulling on a handle, the ___________ muscle activates before the biceps.
anticipatory postural adjustment
__________________ reflexes keep the head in line with gravity and responds to vestibular (otolith) input.
_________________ reflexes keep the head aligned with the body and are mediated by stretch reflexes in the neck.
The _________________________ reflex is stimulated by neck rotation or lateral flexion and produces ____________ of the extremities on the face side of the body and ___________ of the extremities on the other side.
asymmetric tonic neck
_________________ posture results from damage BELOW the level of the superior colliculus (brainstem) and produces extension tone and posturing of all 4 limbs.
_______________ posture results in damage ABOVE the brainstem and results in flexor posture of the arms (or forelimbs) and extension tone and posture in the legs
_______________ is a clinical condition produced by hypertonous (hyperactive stretch reflexes), and results from central nervous system damage
CNS damage can cause _________ which results from hyperactive stretch reflexes or __________ which results from hypoactive stretch reflexes.
_______________ is a non-progressive neonatal disorder that affects the motor system.
Three types of cerebral palsy are:
1. Spastic (most common; due to cortical damage)
2. Atheosis (not common; due to basal ganglia damage)
3. Ataxis (most rare; due to cerebellar damage)
Which type of cerebral palsy is most common?
The motor cortex was first mapped in the dog by ______________ in the 1860s
Fritz and Hitzig
At the turn of the 20th century, ___________________ mapped the motor cortex in humans undergoing brain surgery in Canada
The motor cortex in mammals is arranged somatotopically and distorted such that regions with greater dexterity have __________ cortical representations.
The largest parts of the resulting homunculus are the _________ and ________.
hand and face
True or False: Sheiber demonstrated that digits are not clustered together (somatotopically) in motor cortex.
Are cortical maps stable throughout life and experience? What evidence supports your answer?
No- Sane's study (rat whiskers; cut facial nerve, other areas take over inactive neurons)
Can behavioral experience change the motor representation of the digits? What evidence supports your answer?
Yes- Merzenac monkey study (stimulated digits show differential growth in cortical regions)
Motor cortices include what areas?
1. Primary motor cortex
2. Premotor cortices
3. Supplementary motor cortex
Primary motor cortex receives information primarily from what cortical areas?
1. Primary somatosensory cortex
2. Premotor areas
Premotor cortices receive information primarily from what cortical areas?
1. Posterior parietal cortex: sensory motor transformations
2. Prefrontal cortex: abstract planning and stim affordances (aka how you interact with objects)
Motor and premotor cortices receive from which subcortical structures?
1. Basal ganglia
3. Spinal cord via thalamus
After Laurence and Kuypers (1968) cut the cortical spinal tract in monkeys, what function did they never regain?
Individuated finger movements
How does Laurence and Kuypers (1968) monkey study info relate to humans who experience stroke?
The last function they regain is individuated finger movements
True or False: Meier et al (1993) showed that each muscle is directly associated with a given cortical motor neuron
In the search for what cortical motor neurons might code, what did Evarts (1968) show?
In 1982, Georgeopolis and his colleagues introduced a game-changer in understanding how cortical cells might code for behavior. They showed that ___________________ rather than single neurons code for movement direction.
populations of neurons
Strick (1999) used forearm posture to differentiate between cells that might code for movements in extrinsic coordinates, or rather for muscle activities. They found cells that code for movements in:
1. Intrinsic coordinates
2. Extrinsic coordinates
True or false: Kalaska and colleagues (2003) found that limb dynamics seem to be coded for in cortical cells
When are premotor and supplementary motor areas active relative to movement behavior?
prior to movement
Two regions of premotor cortex mediate different aspects of behavior, list the two areas and the behaviors that they mediate
Ventral PM: PMv = grasp, manipulation, and mirror of grasp
Dorsal PM: PMd = reach
One of the above areas receives dorsal visual stream info and the other ventral visual stream info. Identify which receives which info
PMd = Dorsal Stream
PMv = Ventral Stream
Pers Roland (1980) showed that supplementary motor cortex is active during ___________________
mental imagining of movements
Lesions to SMA produce deficits in _________ coordination
Rizzolatti (1996) revealed ___________ neurons in ventral premotor cortex that are active when an animal uses a particular grasp pattern, and also when watching another animal (experimenter) use the same pattern
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