Week 5 Flashcards
why can’t we tickle ourselves?
send efference copy down so you know what it is going to feel like (you predict what it is going to feel like)
what does the inclusion of the effector parameter indicate?
the muscles for a particular action could not be stored in a GMP
if the muscles for a particular action can’t be stored in a GMP, what is the sequence then?
the sequential ordering is thought to be abstract
what are added to the command during the preparation of the program?
the specific joints and muscles
- supported by bilateral-transfer
bilateral-transfer
transfer of practice effect to other limb
- refining motor program
inputs of GMP
- duration
- force
- effector
specification of motor program
- GMP (abstract, relative timing, relative force)
- GMP with inputs (parameterization)
- motor command
- specific muscle activation and efference released
how does the concept of the GMP address the storage and novelty problems?
- not able to store new information for motor outputs
- general set of programs that pre-exist in motor repertoire - don’t need to store specific programs =, just use same programs and specific effector
-specify force, duration and effector reduces storage problem
novelty
new movements aren’t truly new
- can adapt other programs to perform the action
how does concept of the GMP address the storage and novelty problem - computer analogy?
- one program needs to be stored for each class of problem
- a general program can be run on data it has never seen before
- just have to specify the proper parameters
2 hypotheses of infants and storage and novelty problem
- they come preprogrammed
- build on primitive sets of actions (reflexes)
when is there a relationship between speed and accuracy?
when examining voluntary, goal-directed movements
speed accuracy tradeoffs
- fast movements are less accurate
- accurate movements are now slower
what researcher explain the relationship of accuracy and speed for feedback-based movements?
paul fitts (1954)
fitt’s law
taps between 2 targets as rapidly as possible maintaining 95% accuracy
what does fitt’s law include
- movement time between 2 targets (MT=20s/#taps)
- movement amplitude (A)
- target width (W)
fitts paradigm
index of difficulty
index of difficulty (ID)
log2 (2(amplitude)/width)
what happens when you increase index of difficulty?
movement time increases
what is the main point of fitts law
as you increase ID, MT increases
is it more difficult is the targets are the same width and closer or further apart?
further apart
is it more difficult is the targets are the sample amplitude but one is smaller width then the other?
the one with smaller width is more difficult
fitts equation
MT = a + b * log2(2A/W)
MT= movement time
a= y-int
b= slope
*=multiplied
what is ID measurement
bits of information
what happens if movement amplitude is doubled?
ID increases by 1
what happens if the target width is doubled?
ID decreases by 1
how would you get an ID of 0?
if width was so big that the targets overlaps, there is no amplitude therefore ID=0
graphing Fitts data
strong positive linear relationship between MT and ID
what ID is the highest?
ID 3
- responds to easiest movements
what does fitts law holds for?
- children
- lower-limb movements
- under magnification
- imagined movements
- perceived movements
fitts law in open loop movements (schmidt)
- the width of the line did not change but distance (D) and time required to make the movement (T) did
what was the goal of fitts law in open loop movements?
determine the “spread” about the target as a function of D and T
- target size the participant was effectively using
schmidts law
movements with no vision
- as time increases, the effective target width increases
violation of fitts law
was found when contextual target cues were present
- participants prepare for “worst case scenario”
what causes the fitt’s law violation? (glazebrook, 2015)
- 3 far targets
- 3 middle targets
- 3 close targets
violations for all last targets? (glazebrook, 2015)
analyzed movement trajectories to the target
- if people planning for worst case to see big difference in the beginning
glazebrook et. al, 2015
- participants performed movements to a target location (first, middle or last)
- measured movement variability across the trajectory as an indicator of planning vs. online movement control
what do differences of variability earlier indicate? (glazebrook, 2015)
planning
what doe differences in variability later indicate? (glazebrook, 2015)
control
result of glazebrook, 2015
differences emerged later in the trajectory, meaning the violation could be based on more efficient movement corrections
do we plan for the worst case scenario?
NO - we adapt efficiently
what causes speed accuracy tradeoffs?
impulse-variability theory
impulse-variability theory
- the variability in the duration of a group of contraction is related to mean duration
- variability in force produced increases as function of the force produced
variability
variability increases about 65% but then decreases at higher levels of force output
- movements should become more accurate when more than 65% of force is required
how can we test impulse-variability
aim to target and resistance to exert more and more force or decrease time
schmidt and sherwood, 1982
fastest = less variable
- over 60% of max = variability decreases
what does fitts law state?
that movement time linerly increases with movement difficulty for closed-loop tasks
when does fitts law violation occur?
when amplitudes overlap
definition of motor learning
a set of processes associated with practice or experience that leads to a relatively permanent change in the capability for movement
process
set of events or occurrences that lead to a product or state of change
what processes are we interested in in motor learning?
processes associated with retrieving a motor program from memory
what processes are pharmokinetics interested in?
processes associated with drug delivery
motor learning processes
largely assumed
- some events must have occurred for their learning as a result of practice
practice
the purposeful repetition of a skill or behaviour
- practice makes permanent (you recall things if you practice)
experience
the fact or state of having been affected by or gained knowledge through direct observation or participation (merriam-webster)
- learning by observing or having an event to occur
practice related
smaller contribution of motor development
- basketball
not practice related
nervous system development and learning for the first time
-result of motor development, not practice
- standing and walking
relatively permanent
change of state is not readily reversible
- any change that is readily reversible is not attributable to learning
ex. steak
what happens when you learned something?
you are a different person
- there has been some underlying change that is stable
should learning have a lasting effect?
YES
- cannot change back to your state pre-learning
example of a readily reversible
ice cubes
the product of learning
the ability to move skillfully in a particular situation
what is the goal of motor learning?
strengthen the quality of the internal state such that the capability of the skill will be altered (hopefully improved) in future attemps
capability for movement
stresses the role of the internal states that leads to the skilled behaviour
external factors to capability for movement
- motivation
- physiological states
- fatigue
is learning directly observable?
NO
why does learning involve highly complex phenomenas
- many processes and many possible explanations
- multi-system interactions
is motor learning directly observable?
NO
- we often have to infer these changes based on behaviour
- we measure and test stability of learned behaviours
different types of learning
implicit vs. explicit
- once you have learned you have permanently changed
what is difficult to assess about neural basis of learning?
if changes in neural and physiological activity is correlated with learning or changes in behaviour
(don’t know what causes what)
hebbian processes (Donald Hebbs)
neurons that fire together, wire together
neural networks (geoffrey hinton)
most neurons receive inputs from other neurons
- these neurons are weighted
- neurons can adapt your weight
(way neurons communicate can be adapted)
what can activation in networks be observed by looking at?
- outputs: electrical activity
- energy consumption: bloodflow
functional connectivity analysis
- examine the time-series of fMRI data in different brain regions
- correlate the time-series between different regions of interest (ROIs)
- examine the strength of those relationships
functional connectivity and motor learning
studied have shown the functional connectivity can predict motor learning
- assess how the people adapted
mcgregor and gribble, 2017
measured participants connectivity prior to observational learning protocol
results of mcgregor and gribble, 2017
found that participants who had higher levels of connectivity in sensorimotor regions performed better in learning paradigm
- higher correlation between somatosensory cortex - primary motor cortex
adaptation
the iterative process of adjusting one’s movement to new demands
- often used interchangeably with learning in many fields
- neuroscience is biggest culprit
motor adaptation
the trial to trial modification based on error feedback
- movement retains identity (ex. walking) but one of the parameters are changed
- change occurs with repetition or practice and is gradual over minutes
- the person must de-adapt after the behaviour
what happens when a person de-adapts after the behaviour?
show an aftereffect
example of aftereffect
walking on a treadmill, then getting off
forcefield adaptation paradigm
in first few trials they adapted to the force field
- after force field removed, they have error in opposite direction then adapt
prism adaptation
involve performing reaches to visual targets then
- can offset vision a certain amount of degrees
measuring motor learning in a typical learning experiment
- participant is exposed to a task (acquisition - practice period)
- performance on the task is plotted as a function of trials
- can examine consistency
measuring motor learning
- as you perform tasks for many trials and days they get better
- performance improves over multiple trials
performance curves (is not learning)
- linear curve
- negatively accelerated curve
- positively accelerated curve
- sigmoid (“S”) curve
linear curve
performance outcome increases with time
negatively accelerated curve
performance outcome increased with time but then plateaus over time
positively accelerated curve
little increase in performance overtime, then large decrease after a lot of time has passed
ex. riding a bike
sigmoid (“S”) curve
steady then large increase in performance then plateau again
ex. sports involving continuous movements
factors affecting performance
- between participants variability
- within-person variability
- ceiling effects
- floor effects
between participants variability
performance curves usually represent grouped data
- individual differences get “washed out”
- ends up coming together so just do the average
within-person variability
performance of the individual person varies trial to trial
- average curve may not do a good job of catching individual variations
ceiling effects
limits at the top scale
floor effects
limits at the bottom of the scale
- when participants aren’t getting better
gymnastics
easier to improve your score at mid-level
6-6.5 vs 9-9.5
golf
reducing a score in golf is easier when stroked are high
145-140 vs 75-70
changes in performance and learning
changes in performance levels becomes insensitive to changes in learning
what can how acquisition is measured affect?
how acquisition is measured can affect the interpretation of performance curve
3 criterion of performance curve considerations
- 30% within target diameter on the target
- 15%
- 5%
- must be right criteria for proper results
- pay attention to how performance is assessed during acquisition and change if you need to
how would we want to compare virtual reality training (new method) to physical practice (old method) in learning a surgical skill?
if there is two skilled surgeons, give one a new surgical skill and one a old method and test 24 hours apart to see how well they learned a skill
retention tests
testing participants on the same task after a time interval
24 hours retention interval
most often used for both retention and transfer
- standard, but testing 1-2 months later to reduce transient effects to more accurately asses learning
what happened the longer the retention interval?
the more transient effects are reduced
transfer tests
involve new variations of the practice task
- can involve the tasks with a twist (new speed or conditions) - same procedure but different tools
- can involve a task that has not been practiced before (varying conditions to the task to test learning)
results of retention and transfer tests
things that make you worse in practice (acquisition) make you learn better in the end (retention/transfer)
learning with robotic guidance
best learning with 50% robotic performance
how can we modify exams to make them truly assess learning?
- increase time interval between time learned and time tested (increase retention time)
- more applied questions require transfer
