Module 3-Lecture 1: Motor Systems (Spinal Cord and Brainstem Circuits) Flashcards
The descending systems of the upper motor neurons consist of what two regions?
- Motor Cortex
2. Brainstem Centers
This part of the Brain is responsible for planning, initiating, and directing voluntary movements
Motor cortex
This part of the brain is responsible for basic movements and postural control
Brainstem centers
This part of the brain is responsible for gating proper initiation of movement.
Basal Ganglia
This part of the brain is responsible for sensory motor coordination of ongoing movement
Cerebellum
What two regions of the brain have a direct response with the descending UMN systems? (motor cortex and brainstem centers)
- Basal Ganglia
2. Cerebellum
What are the two possible major pathways for the Descending UMN systems? (Motor cortex and brainstem centers)
- Local Circuit Neurons
2. Motor Neuron Pools
This is where Lower motor neuron integration occurs?
Local Circuit neurons
This is where the lower motor neurons are located?
Motor Neuron pool
The ability of different motor systems to achieve the same behavior is called ____________
Motor Equivalence
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?
- Spatial Orientation
- Movement Planning
- Inverse Kinematic Transformation
- Inverse Dynamic Transformation
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?
Spatial Orientation
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?
Movement Planning
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?
Inverse Kinematic Transformation
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?
Inverse Dynamic Transformation
An effective general way of describing motor control is in terms of ____________ and ____________ models
Forward and Inverse Models
Internal models represent relationships of the ____________ and ____________
- Body
2. External World
The ____________ determines the motor commands that will produce a behavioral goal, such as raising the arm while holding a ball.
Internal Model
The ____________ command acts on the musculoskeletal system to produce the movement
Descending motor commands
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
Forward Model
If both the forward and inverse models are accurate, what will happen?
The forward model (predicted behavior) will be the same
The input to the inverse model (the desired behavior)
Fill in the blank for motor control in terms of forward and inverse models.
Desired behavior => Inverse Model => Motor Command
a. Efference Copy => ____________ => ____________
b. ____________
a. Forward Model => Predicted Behavior
b. Actual Behavior
This control predicts the future, but does not respond to small deviations from the plan
Feedforward Control
This control knows nothing about the future, just always responds.
Feedback Control
Feedforward Control Model
Desired State => ____________ => Motor Command =>Actuator (Muscle)
Feedforward Controller
Feedback Control Model
Movement error has occurred.
Desired State => Feedforward Controller => Motor Command =>Actuator (Muscle) => ERROR
____________=> ____________ => ____________ => ____________
- Sensor (Muscle Spindle)
- Input Processing (Filtering Amplification)
- Sensed State
- Comparator -
The feedforward controller generates a motor command based on a ____________
Desired State
Any errors that occur during the feedforward control are …
Not Monitored
With feedback control, the desired and sensed states are compared at the ____________
Comparator
With feedback control, the desired and sensed states are compared at the comparator to generate a ____________
Error Signal
With feedback control, the desired and sensed states are compared at the comparator to generate an error signal, which helps do what?
Reshape the motor command
With feedforward and feedback control, there can be considerable ____________ in the feedback of sensory information to the comparator
Delay
Movement control is often considered to be ____________, meaning the details of execution are hidden from centers that deal with more complex planning.
Hierarchical
____________ contains the motor neurons that innervate muscle fibers
Motor Neuron Pools
Motor axons exit via the ____________?
Ventral root
As an adult, muscle fibers gets input from how many motor neurons?
1 motor neuron
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?
1 Alpha motor neuron
-Muscle fibers are Innervated by a single motor neuron
Motor neuron pools span across multiple spinal segments. What is the somatotopic organization of motor neurons in the spinal cord?
- Proximal Muscles are more medial in the ventral horn
2. Distal muscles are more lateral in the ventral horn
Motor units can be classified as ____________ and ____________
Fast and Slow Twitch
Which motor units a greater absolute force generation?
Fast Twitch
Which motor units are able to reach 100% of their force faster?
Slow Twitch
Which motor units produce a greater contraction time?
Slow Twitch
Motor units ____________ and simultaneously ____________ in an orderly fashion during muscle activation
- Recruit
2. Increase their firing rate
Orderly recruitment of a motor unit is mediated by different synaptic strengths in the ____________
Spinal motor neuron
The response of a motor neuron to synaptic input depends on its ____________
Size
Two motor neurons of different size have the same ____________ and ____________
- Resting membrane potential
2. Excitatory synaptic current
Why do smaller motor neurons have a higher resistance?
Because the small motor neuron has a …
- Smaller surface area, it has
- Fewer parallel ion channels and therefore a
- Higher resistance.
