Week 10

Question 1

motor learning –>

Answer 1

behavioral component

Question 2

What does motor learning emphasize?

Answer 2

the brain’s role in acquiring, planning, initiating, and modifying movement

Question 3

motor control –>

Answer 3

physioloigcal component

Question 4

motor control is an are of study dealing with:

Answer 4

the understanding of the physiological and neural aspects of movement (may also be described as neuromuscular control)

Question 5

Motor control includes the Interaction of CNS, PNS and musculoskeletal systems that execute:

Answer 5

movement and monitor/ integrate sensory information.

Question 6

Why do we study the cognitive map?

Answer 6

it is a group of abstract ideas that help to describe the control of movement and how a movement can be learned by an individual

Question 7

What does a cognitive map usually include?

Answer 7

contains underlying assumptions:
• interaction of central or peripheral control mechanisms
(• what variables determine the organization of control?)

Question 8

What framework does a cognitive map provide??

Answer 8

• explains the key variables around which movement is organized
• predicts movement control outcomes based on manipulation of these variables
• guide for hypothesis-driven clinical action ( results in active problem solving by the clinician)

Question 9

What is one important characteristic of all motor control theories?

Answer 9

Include an explanation of how we control coordination (ie what variables is the nervous system trying to control and command?)

Question 10

What is coordination?

Answer 10

patterning of head/body/limbs relative to patterning of environment and objects (this definition holds, regardless of the skill of the performer)

Question 11

When we have multiple solutions possible it is called:

Answer 11

motor redundancy or motor adbundance

Question 12

Degrees of freedom =

Answer 12

describes the number of ways in which a given unit (part of the body) is capable of moving

Question 13

What is degrees of freedom related to?

Answer 13

• # of joints moving
• number of muscles/motor units activated
(Example: consider # of joints needed to pick up the cup of coffee)

Question 14

In the degrees of freedom problem, under normal circumstance, ________________________________ exists between a motor problem (task) and a motor solution.

Answer 14

NO ONE-TO-ONE CORRESPONDENCE

Question 15

In the degrees of freedom problem, you have what redundancies?

Answer 15

• redundant anatomical df’s (diff mms/joints)
• redundant kinematics df’s
(diff trajectories, velocities, acceleration / can still achieve same goal)
• redundant neuruophysiological df’s (multiple neurons for same mm)

Question 16

(mental framework) There are 2 predominant theoretical approaches to explain how skilled movement is coordinated and controlled, they are:

Answer 16

1. top-down

2. dynamic interaction

Question 17

(mental framework) top-down =

Answer 17

existence of a command center in brain that makes all decisions regarding movement

Question 18

(mental framework) dynamic interaction =

Answer 18

• command center can’t account for all variations of skilled movement
• skilled movement emerges from dynamic interaction of variables in body, environment, and skill

Question 19

open loop control (feed-forward) =

Answer 19

• downplays feedback in initiation and execution
• suggests top-down hierarchy

(** discrete)
(*** relies on central command / almost a pre-packaged program)

Question 20

closed-loop (feedback) =

Answer 20

• explain movement as outcome of feedback-initiated reflex actions and pre-patterned neural systems
• error detection & correction maintain desired goal

(** serial & continuous)

Question 21

what is the fundamental difference between closed-loop and open-loop control?

Answer 21

fundamental difference = presence of feedback to modify motor demand during the movement

Question 22

Open-loop control mechanisms include a two-level hierarchy:

Answer 22

1. executive (command center generates action plan that contains all necessary information to complete motor response
2. effectors = mm and limbs; carry out command without modification

input –> [perception–> decision making –> motor command]–> output

Question 23

What is the role of feedback in an open-loop control?

Answer 23

1. feedback constantly present, but comes too late to adjust the ongoing movement
2. once pre-structured commands are initiated, command must run as planned
3. feedback received can be used only to modify subsequent attempts

Question 24

When is open loop control most effective?

Answer 24

for controlling movement that occurs in stable, predictable environments where need for modification is LOW

• advance instructions are given that specify what is to be performed, as well as sequence and timing (including movements of accuracy in short duration movements and rapid movement (

Question 25

In the closed-loop controlled feedback system, the command center needs only to generate action plans that intiate movement:

Answer 25

• sensory feedback continually compared to desired movement
• detected discrepancies sent back to command center for correction
• note the difference in the content of the instructions in closed vs. open-loop (open = full command / closed = command to initiate)

Question 26

Give a common/ everyday of a closed-loop controlled feedback system:

Answer 26

• thermostat in house
• stretch reflex (nervous system
• slack-lining (functional activity)

Question 27

What are 4 key components of closed-loop control mechanisms:

Answer 27

1. executive - decision maker
2. effector - enacts the decisions
3. feedback - reference of correctness/goal
4. comparator ( = cerebellum)

Question 28

in a closed-loop control system, executive =

Answer 28

• stimulus identification
• response selection
• response programming

Question 29

in a closed-loop control system, effector =

Answer 29

spinal cord, mm, motor programs

Question 30

in a closed-loop control system, feedback =

Answer 30

• interoceptive = inside of the body

* exteroceptive = outside of body (i.e. visual, auditory)

Question 31

in a closed-loop control system, comparator =

Answer 31

• slow movements: feedback fine tunes mm force patterns

* fast movements: visual checking after completetion of movement

Question 32

Describe the “steps” of close-loop control mechanisms:

Answer 32

1. system goal is defined
2. sensory information is compared to actual information about movement
3. executive is informed about an error
4. executive sends command to the effector
5. match is made, error is corrected to = 0
   (if error = 0, executive sends command to “turn OFF the furnace,” or command for action. If error exists, executive sends command to “turn ON the furnace”)

Question 33

What are the 4 theories of motor control?

Answer 33

1. reflex theory
2. hierarchical theory
3. motor program theories
4. dynamical systems theory

Question 34

Reflex theory =

Answer 34

(based off the work of sir charles sherringtion)
• Basic assumptions = reflexes are the building blocs of all movement / events in EN served as stimulus for action
• Complex behaviors result from CHAINING of reflexes = individual is a passive recipient of externally-produced sensory input that excites motor systems
• sensory –> motor–> sensory (feedback) (monkey unilateral UE deafferentation (DRG cut) - lost mvmt. / this went unchallenged for over 60 years)
• closed-loop in nature

Question 35

What are the limitations of the reflex theory?

Answer 35

CAN’T EXPLAIN:
• Spontaneous or voluntary movements
• fast sequential movements (e.g typing)
• reflexes can be modulated (a single stimulus can trigger various responses)
• novel movements can be carried out
• Taub (1980) - deafferented monkeys
(-bilateral deaffentation: monkeys able to move arms - unilateral deafferentation: monkeys relearned movement while “good” arm constrained)

Question 36

Hierarchial theory =

Answer 36

motor control emerges from reflexes nested w/in hierarchically organized level in CNS
• higher centers always in control of lower centers
• higher centers inhibit reflexes control by lower
• reflexes control by lower centers present only when higher centers are damages
• neuro-maturational theory of development (brain determines infant behavior)

Question 37

What are some current opinions on hierarchical models?

Answer 37

• each level of motor system can act on other levels

* reflexes are only one of many motor control processes

Question 38

What are some limitations of the hierarchical theory?

Answer 38

• can’t explain dominance of reflex behavior in certain adult situations (flexor withdrawal)
• Environment and other non-CNS factors can affect infant movement (infant stepping reflex)

Question 39

What is the influence of hierarchical theory on treatment paradigms (neurorehabilitation) ?

Answer 39

• “When the influence of higher centers is temporarily or permanently interfered with, normal reflexes become exaggerated and so called pathological reflexes appear”
• “The release of motor responses integrated at lower levels from restraining, influences of higher center, especially that of the cortex, leads to abnormal postural reflex activity”