LECTURE 29 - open loop control

Question 1

what is open-loop control?

Answer 1

is a type of control system where the output or action is predetermined based on a set of programmed instructions or a fixed input signal, without feedback or monitoring of the actual output

Question 2

who performed the early studies of open-loop control ?

Answer 2

Sherrington

Question 3

who performed the later studies of open-loop control ?

Answer 3

rothwell

Question 4

describe the early studies done by Sherrington :

Answer 4

sectioning of dorsal roots and the absence of movement

Question 5

describe the later studies done by Rothwell :

Answer 5

individuals can program actions without sensory input

Question 6

who started studying individuals with peripheral neuropathies (people who had selective damage to their dorsal roots that impeded any sort of somatosensory or proprioceptive information from their muscle spindles getting access into their CNS) ?

Answer 6

rothwell

Question 7

it was originally thought to be compelling evidence that a closed-loop system control is the only mode of control that really supports purposeful movement …

Answer 7

we dont really have an open-loop system of control

Question 8

what does deafferentation mean ?

Answer 8

refers to the loss or severing of sensory input to a particular area of the nervous system

Question 9

in what study does a gentleman perform a thumb to finger movement ?

Answer 9

deafferentation Rothwell study

Question 10

what do we see in the images in regards to deafferentation ?

Answer 10

successive snapshots of gentleman able to perform the movement in the absence of sensory feedback from his muscle spindles and from a somatic sensory system

Question 11

where is peripheral neuropathies in their extremities ?

Answer 11

right hand and in both of their feet

Question 12

in what case can an individual have complete vision, can plan movement but cannot make adjustments ?

Answer 12

open-loop control deafferentation

Question 13

what is central pattern generator ?

Answer 13

a neural network that generates rhythmic and coordinated patterns of motor activity in the absence of sensory feedback or descending motor commands

Question 14

where did we first see the central pattern generator ?

Answer 14

50s Soviet Union

Question 15

what is “in some pint of our spinal cord, there are group of neurons or a cluster of neurons that can control these arthymeic movements” referred as ?

Answer 15

central patter generators

Question 16

what experiment was used to demonstrate central pattern generator ?

Answer 16

mesencephalic (midbrain) cat supported on a treadmill

Question 17

describe the mesencephalic cat supported on treadmill experiment :

Answer 17

• cat who’s had this midbrain procedure performed on it
• when the cat is place on a treadmill, they can walk
• treadmill is gradually increasing speed and you. can see that the cat demonstrates a fairly normal transition from walking to running

Question 18

what happens as soon as you take away this input trigger (the treadmill being on) ?

Answer 18

the whole system will stipend the cat will cease to be able to walk (without this trigger input (that moving treadmill), the cat would not be able to walk and then as the treadmill increase speed, would not be able to elicit a transition from walk to run

Question 19

why is a treadmill good in regards to these central pattern generator experiments ?

Answer 19

• way to promote movement
• improve cardiovascular health
• with therapy individuals can get a lot better

Question 20

what type of movement is present in central pattern generator patients on a treadmill ?

Answer 20

rhythmic and stereotypes movement and gait

Question 21

what are ballistic actions ?

Answer 21

rapid and explosive movements that are initiated with a high degree of force and precision and are typically executed in a single, uninterrupted motion

Question 22

what are the three triphasic EMG bursts’ ?

Answer 22

1. primary agonist burst
2. antagonist burst
3. secondary agonist burst

Question 23

what is an example of the primary agonist burst ?

Answer 23

triceps : guiding limb to target

Question 24

what is an example of antagonist burst ?

Answer 24

biceps : breaking or slowing the limb

Question 25

what is an example of secondary agonist burst ?

Answer 25

prevents limb from oscillating

Question 26

what is triphasic EMG ?

Answer 26

is a method of analyzing muscle activity based on the waveform of the recorded EMG signal

Question 27

when are contractions all pre planned entirely in advance of movement execution ?

Answer 27

ballistic actions

Question 28

what did Wadman et al (1976) examine ?

Answer 28

wanted to examine the EMG profiles by demonstrating an open-loop mode of control, because this triphasic burst of EMG activity was entirely present during these blocked trials

Question 29

what were the results of the wadman et al study ?

Answer 29

• unblocked trials : typical triphasic EMG
• blocked trials : EMG burst similar to the unblocked trials for 110,s after the initial burst
• antagonist burst in blocked trials occurred at the same time as unblocked