MC Exam 2: Central Inputs to Motor Control

Question 1

What is closed loop control?

Answer 1

sensory information is used to control information, using constant feedback to meet a movement goal and minimize error

Question 2

What is open loop control?

Answer 2

ballistic movements, pre-programmed, not sensitive to feedback

no time to modify movement

Question 3

What is the reflex chaining hypothesis?

Answer 3

sensory information initiates a movement, one movement creates a trigger for the next movement

thought to explain order of skilled movements

Question 4

What were early experiments to test reflex chain theory?

Answer 4

monkey deafferentation, patients with deafferentation (SCI, sensory neuropathy in diabetes)

Question 5

What experiments were done to lead to central pattern generators?

Answer 5

mesencephalic or spinal preparations of cats

Question 6

What are central pattern generators?

Answer 6

circuits remain intact below level of lesion, circuits need a stimulus to start rhythm but not to maintain it, self perpetuating

controls frequency and pattern but not force

Question 7

What clinical application was a result of CPG?

Answer 7

body weight support treadmill training- concept to trigger CPG and rewire CNS

results still inconclusive

Question 8

What is the reflex reversal phenomenon in locomotion?

Answer 8

a stimulus to the foot can cause 2 different patterns of action depending upon the phase of the stepping cycle if an obstacle is introduced

Question 9

What are the two actions in reflex reversal?

Answer 9

1. flexor withdrawal during swing

2. extensor pattern during stance

Question 10

How does motor system know the timing of events in rapid movements?

Answer 10

by turning agonist and antagonist on/off with precise timing to control moments

Question 11

What is the degrees of freedom problem?

Answer 11

there are too many joints and muscles to control at one time during a movement

therefore led to theory of motor programs

Question 12

How can we test theory of motor programs?

Answer 12

by inhibiting actions

can you inhibit a well known action immediately? can you interrupt a motor program

Question 13

What experiment was performed by Logan?

Answer 13

typing experiment, subjects would type 2-3 characters after the stop tone

indication that there is a highly developed motor program for typing “the”

Question 14

What was Slater-Hammel experiment?

Answer 14

press button at the “8” like the arcade game (75% of trials)

found 166 ms point of no return

Question 15

What action did Gray study?

Answer 15

baseball swing, “check swing”

found similar time for point of no return at 166 ms

Question 16

What is the connection between sensory information and motor programs?

Answer 16

you need to know the position of your other muscles and joints prior to making your movement

EX: where are you starting, what choices/effector, how many ways can it be done

Question 17

What arr errors in program selection?

Answer 17

1. error in performers choice of action- soccer goalie diving wrong way
2. error due to poor perception of environment led to poor choice

this requires performer to go back to response selection stage and make new choice. very time costly

Question 18

What are errors in program execution?

Answer 18

1. unexpected perterbations in the environment( misjudging weigh of milk carton)
2. neural noise- mis calibrated sensory circuits, synaptic drift

need to make adjustments to current program, can be a more rapid connection

Question 19

How is neural noise connected to performance?

Answer 19

neurons are constantly influx and always changing connections therefore athletes need to rehearse movements before and event to re calibrate connections

Question 20

What is the hierarchical levels of control?

Answer 20

blending both open and closed loop controls

“a higher order, open loop control system has under it a set of closed loop processes that ensure the movements intended goal in face of perturbations”

Question 21

What are two motor program limitations?

Answer 21

1. storage- an issue of retaining learned information

2. novelty- an issue of making new movements (not every tennis stroke is same)

Question 22

What are generalized motor programs?

Answer 22

has invariant spatial and temporal parameters (ex. handwriting with different parts of the body)

don’t need a specific program for every different task

Question 23

What are invariant parameters of GMP?

Answer 23

what is constant?

1. order of events
2. relative timing
3. relative force

Question 24

What are controlled parameters of a GMP?

Answer 24

what can brain control?

1. overall duration
2. overall force
3. muscle selection