Module 19 - Lecture 12 - Motor Control

Question 1

Define Motor control

Answer 1

The study of the nature and control of known movements.

Question 2

How do you design an experiment to understand motor control from a psychomotor approach

Answer 2

Psychomotor approach –> more in “cognitive psychology” It is an applied scientific method where essentially you would want to measure a performance of a task. (because we are thinking the control of the movement) Then we would want to manipulate the aspects of the task and understand… How this would change the behaviour that we were observing If we are able to show that there is some manipulation that causes an effect in the performance, we would then make some inferences of what may be inducing this changes!!! –> you may develop your own model The steps would be the following: Measure task performance Manipulate aspects of the task Study the behavioural effect Make inferences about the underlying models of control

Question 3

How do you design an experiment to understand motor control from a physiology approach - neurophysiology?

Answer 3

Cause and effect –> you can either excite a structure or do a controlled lesion (like surgery) of neurophysiological structures. And then you can observe what the effect would be, to come to a conclusion of what the structure contributes to. Observational - with more of an epidemiological approach - with modern radiography = MRi. WE can simultaneously measure motor function while individuals complete tasks = we can observe the changes of the performance

Question 4

What is the definition of factors that explain an observed movement (ie task, individual, and environment)?

Answer 4

Individual: Anatomical, physiological and cognitive abilities of the “actor” Environment: Area around individual where task is performed - Could be predictable or unpredictable - Relevant or non-relevant features Task: End point or goal “retrieve cup” - Has a variety of “sub-goals” or “dimensions” that can be measured - Spatial vs temporal, outcome vs process, integration of parts (discrete vs serial vs continuous), cognitive vs motor, closed vs open, self vs external pace

Question 5

What are the 3 parts of the information processing model? Define them

Answer 5

Three fundamental stage

1. Stimulus-identification (Perception)
   
   1. Sensory information from the environment (internal and external) to detect and identify a stimulus
2. Response- Selection
   
   1. Decide what to do (this can be nothing)
3. Response-Program/execution
   
   1. What we must prepare and initiate to achieve our selected response as a “skilled motor behaviour”

Question 6

What is “short term sensory storage”.

Answer 6

Sensory information is stored in sensory memory just long enough to be transferred to short-term memory. Humans have five traditional senses: sight, hearing, taste, smell, touch and all sensory signals travel to the brain. All sensory information (that travels through AP) can be received by the thalamus and go to primary sensory cortex areas.

Question 7

What is the capacity of the short term sensory storage?

Answer 7

Almost limitless capacity → everything that is going on in the environnement we can sense.

Question 8

How long does the short term sensory storage last?

Answer 8

The sensory information is accepted but we do not have much “record or memory of it”
Last only 250 ms

Question 9

Is the short term sensory storage perceived consciously?

Answer 9

The sensory information has the potential for “conscious recognition” or “perception” by the brain.
But the capacity to “perceive” is limited, therefore not all sensations reach perception

Question 10

What is the definition for attention and the two general things one attends to?

Answer 10

Attention is a filter with a finite capacity that controls access of some sensations at the cost of not perceiving others.

• Example of attention, if you are trying to figure out the identity of the orange.. You might not notice the apples around it = attention has a cost. → refer to the image on the slides to know exactly what I mean
• Attention increases the “salience” to enhance sensory information (louder, clearer, faster)

Two general things we attends to:

• “Spaces” (an actual area where something is going on) or “ identify features” (ex. Someone’s speech, cadence)

Question 11

Define endogenous and exogenous attention.

Answer 11

Endogenous attention = top-down = we select what to attend to fulfill a desire
Exogenous attention = bottom-up = the stimulus has natural salience that captures attention

Question 12

What does exogenous attention suggest about short term sensory storage?

Answer 12

Bottom-up attention suggests evidence of some processing in sensory storage.
Recall that attention is our ability to perceive some sensation at the cost of other types of sensation… It does suggest that in my background if something more exciting comes along, we may have learned some natural salience and therefore it suggests that there is some kind of processing that does occur within our sensory storage system (that limited one), that can just grab our attention!!!

Question 13

How does attention to sensations lead to a meaningful element for perception?

Answer 13

The sensations that our body is receiving is being “packaged” as a pattern (recall associativity) contacting a memory from our past, and that memory is known as a “long term memory”. And it is the “long term memory” that is meaningful and we can work on; not the individual sensations themselves. This moves the sensory information into “working memory” to be worked upon.

• This process reduces the amount of resources you need for attention
• The memory starts to put everything into context

Question 14

Define the signal detection theory.

Answer 14

Signal detection theory: Detection theory or signal detection theory is a means to measure the ability to differentiate between information-bearing patterns (called stimulus in living organisms, signal in machines) and random patterns that distract from the information (called noise, consisting of background stimuli and random activity of the detection machine and of the nervous system of the operator).

Question 15

How does the signal detection theory assists with “contacting a memory”?

Answer 15

How does this theory assist with “contacting a memory”:

• Sensory information is ambiguous and ambiguity can be resolved by bottom up and top down factors.
  
  • Bottom-up = clarity (sharpness/contrast of stimulus) + intensity (magnitude of the stimulus
  • Top-down = prior knowledge for “patterning”
• The faster you resolve ambiguity the faster you contact the memory for information processing.

Question 16

How does memory patterning come to be (ie would it be known right away or is it “learned”)?
How does patterning aid in perception?

Answer 16

• Memory patterning In psychology and cognitive neuroscience, pattern recognition describes a cognitive process that matches information from a stimulus with information retrieved from memory.
• Pattern recognition occurs when information from the environment is received and entered into short-term memory, causing automatic activation of a specific content of long-term memory. An early example of this is learning the alphabet in order. When a carer repeats ‘A, B, C’ multiple times to a child, utilizing the pattern recognition, the child says ‘C’ after he/she hears ‘A, B’ in order. Recognizing patterns allows us to predict and expect what is coming. The process of pattern recognition involves matching the information received with the information already stored in the brain. Making the connection between memories and information perceived is a step of pattern recognition called identification. Pattern recognition requires repetition of experience. Semantic memory, which is used implicitly and subconsciously is the main type of memory involved with recognition
• This means that memorizing a “pattern” is learned over time but provide contrast to stimulus, a working memory is limited to 4-7 chunks → a chunk can be a meaningful package/pattern of information.
• Once the association is made we benefit from an improved ability to resolve the ambiguity of the stimulus.

Question 17

How is memory patterned evidenced in the De Groot study?

Answer 17

Evidence for Chunking Theory. One of the main pieces of evidence supporting the chunking theory is the chess experiment carried out by De Groot (1965). In this pretty simple experiment, De Groot was able to show the difference in the way that experts and novices reconstruct certain aspects of chess in their minds.
*If you present the chest board to better players –> when the chest board is set up as a partially played game = can now do meaningful patterns = strategies that you can make over time
*If you present the chessboard with no pattern in mind, simply putting the pieces at different places -> less able to retain the pattern = evidence to support the theory of MEANINGFUL PATTERNS

Question 18

What processes occur during response selection?

Answer 18

We start by selecting the “appropriate action” → which is essentially thinking, then planning and then deciding.

The way we do this is by having attention keeps the perception of working memory. And this overlap can contact additional memories. This provides information of previous goals and outcomes (rewards and costs) to predict consequences of an action.

Question 19

What happens when you have more choices to choose from?

Answer 19

Choosing how to act takes time, and therefore having more choices slows us down.

Question 20

What happens when the number of choices doubles?

Answer 20

When the number of choices double, the reaction time doubles
This is known from the Hick-Hyman’s Law → Which states that increasing the number of choices will increase the decision time logarithmically = RT = A + B *log2(N)

Question 21

What is anticipation and how does it impact attention and response selection?

Answer 21

• Anticipation = it is information gained before signal to know where to attend or the correct response.
• With anticipation, you can speed up the process, because we have already undergone this selection process, at an earlier period of time that gives us the illusion of faster reaction time.
• How does anticipation impact attention → it is faster since we know what we should be paying attention to
• How does anticipation impact response selection → it is also faster since we know what the desired response we are to do before the cue.

Question 22

How can automaticity develop?

Answer 22

• Automaticity can be developed with experience we “anticipate” logical guesses (example, soccer ball) because sensory information is in “packages” and we are “association machines”. The new strategies that we learn with experience/practice or some type of learning exposure are the “cue” we may have learned them “implicitly”.
• That being said, a highly practiced stimulus response pairing becomes “automatic” through the cerebral cortex.
  
  • Example = the alphabet.
  • Sensation has a singular linked perception/outcome
• We can create this automaticity due to plasticity being the “highway”

Question 23

Define the process of motor ideation.

Answer 23

Working memory for “motor programs”
Contemplates multiple motor programs but only one will be executed
What is executed could be a series of motor programs executed in sequence (serial tasks)

Question 24

What is a general motor program?

Answer 24

• It is a unique form of long term memory.
• Represent a general class of movement coding for “relative timing coordination” → like direction changes.
• A motor program = relative time = ratio (% total)

Question 25

What is the irrelevant/invariant feature of a general motor program?

Answer 25

The irrelevant feature is that the relative timing coordination of the movement → this is always constant

Question 26

What are some parameters of a general motor program?

Answer 26

• The map to any single effector like a limb
• Amplitude of the movement
• Speed of the movement

Question 27

What does the memory drum theory suggest about motor programing? What features can make a movement more “complex”?

Answer 27

• The memory drum theory suggests that the reaction time increases as a task becomes more and more complex. A whole movement planned before execution thus more complex movements take longer to program.
  
  • Features that can make a movement more “complex”:
    
    • Number of movements and limbs
    • Accuracy of the task (more accurate movements take longer to plan)
    • Movement duration

Question 28

What does the Wadman Limb Block experiment and the APA suggest about motor programming?

Answer 28

Wadman Lim block → the experiment where the patient was asked to move their elbow coded for 3 phases and even if the movement was blocked, the same 3 phases on the EMG pattern remained unchanged with “block”. Evidence that motor programs execute in whole !!! Evidence towards motor programing has an “open loop” desired state

APA → In general motor control there has an external or task focus. Yet, observed muscle patterns complex timing of factors we do not even consider. Although the external focus on the image is lifting the lever, we see this incredible complex muscle pattern that is crossing a variety of joints. This is due to neuroplasticity and associativity; we have learned by trial and error to become more successful for a certain environment.

Question 29

A general motor program (an invariant timing / movement pattern) is “scalable” (via parameters) and this defines a principle called the “motor schema”. What happens in motor programming to fit the GMP to a novel motor program?

Answer 29

Parameterization (setting the parameters/the variables that can be modified like the speed (total time), amplitude, effector (limb used)) allows the GMP to fit novel situations (sensation)

Question 30

What is it called if the fit of a general motor program to a novel motor program occurs in a practice space that you have engaged in before?

Answer 30

Interpolation = fit parameter for GMP within framework of exposed history

Question 31

What is it called if the fit of a general motor program to a novel motor program occurs in a situation outside of your practice space?

Answer 31

Extrapolation = scale parameters of GMP outside of practice history

Question 32

What is the general idea of program refinement and what structure contributes to this?

Answer 32

• Program refinement is from the transition of motor plan to program execution. There are many overlapping ways to access motor neurons that could execute “similar” but not quite right “competing” movements; therefore the question is how we let only the right one through? = NEURAL FILTER!
• The structures to contribute to this = BASAL GANGLIA = acts as the response selection filter → Going through the basal ganglia will select the one motor pattern that we want to execute the movement.

Question 33

What is the psychological refractory period?

Answer 33

• The psychological refractory period = it is a given time to plan the first motor program until the next one is prepared. You must start the first motor program before executing the second.
  
  • The idea is going through this process of motor planning, where we have our motor programming before we execute it. We actually need to fully have our motor program ready and shuttled off to begin execution before we can let through another motor program.
  • It is a refractory period –> a set given a time of when we can actually allow for a new motor program.

Question 34

What is the general take away from the double step paradigm?

Answer 34

• The individual only had to execute the motion of a single arm to a specific cue; if you heard a sound you needed to lift your right arm and then another sound to lift your left arm.
• The experimenter varied the period of time that you would have the sound to lift your right hand to when they presented the sound for you to lift the left hand. What they were able to show is when these stimuli were presented very close in time … to when the second signal was provided.. The period of time it took for the individual to execute the second motor program to lift their left arm, would actually get longer and longer as the interval between the stimuli became shorter and shorter.
• Demonstrates that you must start the first motor program before executing the second motor program. It is evidence to prove that executing a motor program represents a “bottle neck”

Question 35

What is open loop control?

Answer 35

• An open loop control is a feedforward loop
• It includes information processing model including “response selection“ of best motor plan
• It also includes advanced instruction of sequence and timing of muscles where the motor program could be executed essentially without modification.

Question 36

What is closed-loop control? What is the benefit of closed-loop control? What is required to execute it?

Answer 36

• The close-loop system will detect with the use of a receptor the actual state of the taks and compare it with the efference copy that was made by the open loop/expected state. These receptors will define error and feedback the comparator to the central mechanism that will then correct the error.
• It takes time for sensory input to adjust movement but there are various ways to do so :
  
  • Our spinal reflexes → if our stretch reflex, therefore is our muscle spindles deviated from the goal orientated task - the coactivated gamma drive can detect that the muscle is not in the right spot and you can induce that in order to get myself in the right position.
  • UMN reflexes → example, the vestibular nuclei, it might have a set orientation that it thinks we want to be in, and if things go to plan the AP would meet the reality but if it was not then the reflex could help correct the posture → it is an automatic response that can also include the cerebellum
  • Can also include voluntary process → essentially go through the whole information processing model once again to know that there is an error and develop a new motor program to help the preceding model
  • ***keep in mind that there is a refractory period
• The benefit of closed loop control is that it can improve accuracy (we can learn from our errors!!!) with feedback control.
  
  • We need comparators to give feedback and allow for changes in our motor programming:
    
    • Spinal cord (M1)
    • Brain stem (M2)
    • Comparator (grey)
      
      • The cerebellum
      • Also information back to the cortex.

Question 37

Can closed-loop control without an open loop? Can open exist without closed?

Answer 37

There is an interaction between open and close loops to achieve skilled movement.
It would not be possible to have a closed loop without an open loop since you need something to compare, need the open loop to have something to know that there is an error to correct. Open loop could exist alone, things would be planned, but we would never be able to learn from our errors.

Question 38

How can attention change over time? What is the implication on “dual task”?

Answer 38

• Attention has a set demand/cost; finite resource, but the relative “cost” of attention to a task can change over time.
• This allows for the processing or conscious recognition of additional information or processing dual-tasks. As you become more of an expert, you do the same task but the amount of attention you need is reduced.

Question 39

What happens when you attend too much or too little to a sensorimotor task?

This is proven by which study? Explain.

Answer 39

When you attend too much or too little to a sensorimotor task, both instances will deteriorate your performance.

• This is proven by the Huxhold 2006 study → a standing balance experiment where subjects had a single task or variety of difficult cognitive dual-task.
  
  • (This study was comparing older adults to younger adults who were trying to do a relatively simple balanced task –>they measure their COP and monitoring the attentional focus of the subjects)
  • They were able to conclude that too much focus on a “automatic task” = like standing in this experiment deteriorates performance; and not enough attention deteriorates performance

Question 40

Contrast external and internal focus.

Answer 40

External focus: natural expert performance, focus on the task
Internal focus: not natural expert performance, focus on the own performance

Question 41

What is the hypothesis why internal focus leads to “choking” (like messing up in a sport at the end of a game)?

Answer 41

• It is that shift of attention to features that you normally do not utilize in your typical motor control. It starts to change the essential overlap of the network of neurons that we are often using to perform the task with the capacity that we have built through learning.
• MOTOR CONTROL = the idea of plasticity and building the strongest pathway… if we try to change a single element to the way the neurons are connected we can have these motor dysfunctions where it may lead to a noticeable decline in performance
• Motor control is most efficient when there is maximum overlap with the neural resources “networks” that are most naturally used (the strongest pathways).