Module 3-Lecture 1: Motor Systems (Spinal Cord and Brainstem Circuits)

Question 1

The descending systems of the upper motor neurons consist of what two regions?

Answer 1

1. Motor Cortex

2. Brainstem Centers

Question 2

This part of the Brain is responsible for planning, initiating, and directing voluntary movements

Answer 2

Motor cortex

Question 3

This part of the brain is responsible for basic movements and postural control

Answer 3

Brainstem centers

Question 4

This part of the brain is responsible for gating proper initiation of movement.

Answer 4

Basal Ganglia

Question 5

This part of the brain is responsible for sensory motor coordination of ongoing movement

Answer 5

Cerebellum

Question 6

What two regions of the brain have a direct response with the descending UMN systems? (motor cortex and brainstem centers)

Answer 6

1. Basal Ganglia

2. Cerebellum

Question 7

What are the two possible major pathways for the Descending UMN systems? (Motor cortex and brainstem centers)

Answer 7

1. Local Circuit Neurons

2. Motor Neuron Pools

Question 8

This is where Lower motor neuron integration occurs?

Answer 8

Local Circuit neurons

Question 9

This is where the lower motor neurons are located?

Answer 9

Motor Neuron pool

Question 10

The ability of different motor systems to achieve the same behavior is called ____________

Answer 10

Motor Equivalence

Question 11

The task of generating a Goal-Directed movement is often broken down into a set of sequential stages, the details of which are still being elucidated. What are the 4 sequential stages for generating a particular movement?

Answer 11

1. Spatial Orientation
2. Movement Planning
3. Inverse Kinematic Transformation
4. Inverse Dynamic Transformation

Question 12

To reach for an object, the object and hand are first located visually in a coordinate system relative to the head. This is what stage of sensorimotor transformations?

Answer 12

Spatial Orientation

Question 13

The direction and distance the hand must move to reach the object (the endpoint trajectory) are determined based on visual and proprioceptive information about the current locations of the arm and object. This is what sage of Sensorimotor transformation?

Answer 13

Movement Planning

Question 14

The joint trajectories that will achieve the hand path are determined. The transformation from a desired hand movement to the joint trajectory depends on the kinematic properties of the arm, such as the lengths of the arm’s segments. This is what stage of sensorimotor transformations used to generate a movement?

Answer 14

Inverse Kinematic Transformation

Question 15

The joint torques r muscle activities that are necessary to achieve the desired joint trajectories are determined. the joint torques required to achieve a desired change in joint angles depend on the dynamic properties of the arm such as the mass of the segments. This is what stage of the sensorimotor transformations used to generate a movement?

Answer 15

Inverse Dynamic Transformation

Question 16

An effective general way of describing motor control is in terms of ____________ and ____________ models

Answer 16

Forward and Inverse Models

Question 17

Internal models represent relationships of the ____________ and ____________

Answer 17

1. Body

2. External World

Question 18

The ____________ determines the motor commands that will produce a behavioral goal, such as raising the arm while holding a ball.

Answer 18

Internal Model

Question 19

The ____________ command acts on the musculoskeletal system to produce the movement

Answer 19

Descending motor commands

Question 20

A copy of a motor command is passed to a ____________ that simulates the interaction of the motor system and the world and can therefor predict behaviors

Answer 20

Forward Model

Question 21

If both the forward and inverse models are accurate, what will happen?

Answer 21

The forward model (predicted behavior) will be the same

The input to the inverse model (the desired behavior)

Question 22

Fill in the blank for motor control in terms of forward and inverse models.
Desired behavior => Inverse Model => Motor Command
a. Efference Copy => ____________ => ____________
b. ____________

Answer 22

a. Forward Model => Predicted Behavior

b. Actual Behavior

Question 23

This control predicts the future, but does not respond to small deviations from the plan

Answer 23

Feedforward Control

Question 24

This control knows nothing about the future, just always responds.

Answer 24

Feedback Control

Question 25

Feedforward Control Model | Desired State => ____________ => Motor Command =>Actuator (Muscle)

Answer 25

Feedforward Controller

Question 26

Feedback Control Model Movement error has occurred. Desired State => Feedforward Controller => Motor Command =>Actuator (Muscle) => ERROR ____________=> ____________ => ____________ => ____________

Answer 26

1. Sensor (Muscle Spindle) 2. Input Processing (Filtering Amplification) 3. Sensed State 4. Comparator -

Question 27

The feedforward controller generates a motor command based on a ____________

Answer 27

Desired State

Question 28

Any errors that occur during the feedforward control are ...

Answer 28

Not Monitored

Question 29

With feedback control, the desired and sensed states are compared at the ____________

Answer 29

Comparator

Question 30

With feedback control, the desired and sensed states are compared at the comparator to generate a ____________

Answer 30

Error Signal

Question 31

With feedback control, the desired and sensed states are compared at the comparator to generate an error signal, which helps do what?

Answer 31

Reshape the motor command

Question 32

With feedforward and feedback control, there can be considerable ____________ in the feedback of sensory information to the comparator

Answer 32

Delay

Question 33

Movement control is often considered to be ____________, meaning the details of execution are hidden from centers that deal with more complex planning.

Answer 33

Hierarchical

Question 34

____________ contains the motor neurons that innervate muscle fibers

Answer 34

Motor Neuron Pools

Question 35

Motor axons exit via the ____________?

Answer 35

Ventral root

Question 36

As an adult, muscle fibers gets input from how many motor neurons?

Answer 36

1 motor neuron

Question 37

From the spinal cord, Alpha motor neurons descend towards a specific muscle and innervate it. How many Alpha motor neurons are there to stimulate a muscle?

Answer 37

1 Alpha motor neuron -Muscle fibers are Innervated by a single motor neuron

Question 38

Motor neuron pools span across multiple spinal segments. What is the somatotopic organization of motor neurons in the spinal cord?

Answer 38

1. Proximal Muscles are more medial in the ventral horn | 2. Distal muscles are more lateral in the ventral horn

Question 39

Motor units can be classified as ____________ and ____________

Answer 39

Fast and Slow Twitch

Question 40

Which motor units a greater absolute force generation?

Answer 40

Fast Twitch

Question 41

Which motor units are able to reach 100% of their force faster?

Answer 41

Slow Twitch

Question 42

Which motor units produce a greater contraction time?

Answer 42

Slow Twitch

Question 43

Motor units ____________ and simultaneously ____________ in an orderly fashion during muscle activation

Answer 43

1. Recruit | 2. Increase their firing rate

Question 44

Orderly recruitment of a motor unit is mediated by different synaptic strengths in the ____________

Answer 44

Spinal motor neuron

Question 45

The response of a motor neuron to synaptic input depends on its ____________

Answer 45

Size

Question 46

Two motor neurons of different size have the same ____________ and ____________

Answer 46

1. Resting membrane potential | 2. Excitatory synaptic current

Question 47

Why do smaller motor neurons have a higher resistance?

Answer 47

Because the small motor neuron has a ... 1. Smaller surface area, it has 2. Fewer parallel ion channels and therefore a 3. Higher resistance.