Block 1 - Aspects of higher control

Question 1

What is the Fitt’s law equation?

Answer 1

LOG(2A/W)
Simplified to target distance/size

Question 2

What does Fitt’s law describe

Answer 2

Speed of movement influences accuracy of movement

Question 3

What is the two-third power law?

Answer 3

The more curved the movement, the slower the movement is - e.g. running around the bend of the athletics track

Question 4

How do you find the two-third power law?

Answer 4

2/3 curvature proportional to angular velocity

Question 5

What are the 4 stages of movement?

Answer 5

1 Localisation
2 Planning
3 Execution and control
4 Adaptation

Question 6

What is space?

Answer 6

A set of points with added structures

Question 7

Name two different spaces.

Answer 7

1 End effector space - external
2 configuration space - internal

Question 8

What is a coordinate system?

Answer 8

A set of unique numbers that uniquely determine a point in space
End effector space - X, Y, Z
Configuration space - a1, a2, a3

Question 9

Name the two different origins of the coordinate system and where are localised?

Answer 9

Egocentric - attached to the body
Allocentric - attached to external object

Question 10

What is the direction of inverse kinematics?

Answer 10

End effector space to configuration space

Question 11

What is the direction of forward dynamics?

Answer 11

Configuration space to end effector space

Question 12

What is redundancy in inverse kinematics?

Answer 12

One end effector space can have multiple configuration spaces

Question 13

What is kinetics/dynamics?

Answer 13

The number of torques/amount of force required to produce a certain movement

Question 14

What is inverse dynamics?

Answer 14

Kinematics to kinetics
Using movement to determine force required

Question 15

What is forward dynamics?

Answer 15

Kinetics to kinematics
Using force to determine movement produced

Question 16

What equation shows the relationship between kinematics and kinetics?

Answer 16

Newton’s second law - F = Ma

Question 17

What are the two types of control?

Answer 17

Feedforward and feedback

Question 18

Advantages and disadvantages of feedforward control.

Answer 18

+ Movement controlled without processing of external info
- Cannot correct errors
- Accumulation of errors
- Not flexible to different environments
- Cannot generalise to all movements

Question 19

Advantages and disadvantages of feedback control.

Answer 19

+ Flexible
+ Allows for errors
+ Generalisable
- Time consuming
- Can become unstable due to high gain

Question 20

What sensory information is required for localisation and planning?

Answer 20

Visual and auditory - for target
Proprioception - knowledge of the body

Question 21

What are the 3 transformations to carry out movement?

Answer 21

1 Movement planning
2 Inverse kinematics
3 Inverse dynamics

Question 22

What coordinate system does localisation + planning, and, execution + adaptation take place?

Question 23

Monkeys

What did Cohen and Anderson demonstrate in the Posterior Parietal Cortex in relation to movement localisation and planning?

Answer 23

The saccadic region, reaching region and grasping region are all in close proximity

Therefore movement is closely coordinated by hand and eye movement

Question 24

Further to Cohen and Anderson research of the PCC, what did Bautista find?

Answer 24

Neural recordings associated with gaze direction.

Therefore planning is based around the eye-centre coordiate

Question 25

What coordinate centre is associated with movement planning?

Answer 25

Eye-centre coordinate

Question 26

What research by **Raibert** supports the process of movement planning?

Answer 26

Asked p's to write a sentence using different body parts Style was preserved Therefore, we think about trajectory before movement

Question 27

What happens in the joint space when draw a straight line with your hand?

Answer 27

Curved line Same occurs when drawing straight line in joint space

Question 28

What did **Marasso's** study show about straight line hand trajectories?

Answer 28

Asked p's to move hand from centre point to object Hand produced bell-shaped curves Shoulder and elbow produced curves with high variability Therefore planning happens in end-effector space

Question 29

In what space does planning take place?

Answer 29

End-effector space

Question 30

What happens if you change the distance when reaching a straight line?

Answer 30

Velocity profile either increases or decreases, but the bell-shape curve remains the same Further emphasising planning happens in the end-effector space

Question 31

What is variability?

Answer 31

Movement inaccuracies occur when there are errors in movement transformations

Question 32

Name the 3 sources of variability.

Answer 32

1 Input 2 Intrinsic - neural noise of membranes 3 Output - signal dependent noise

Question 33

What is the inverse model of the internal model?

Answer 33

Determines motor commands based on a behavioural goal

Question 34

What is the forward model on the internal model?

Answer 34

Output of inverse model is the motor command Command sent to muscles and produces efferent copy sent to the brain

Question 35

What is an efference copy?

Answer 35

Information used to predict behaviour

Question 36

What did **Graziano's** research show in motor execution in monkeys?

Answer 36

Stimulation of specific areas in motor cortex results in different movement Stimulating reaching region showed reaching in specific directions

Question 37

**Georgopulus** study showed what when stimulating different neurons?

Answer 37

Each neuron has there preferred movement of direction - called directional tuning

Question 38

When is feedforward control needed?

Answer 38

Saccadic eye movement Vestibulo-ocular reflex

Question 39

Name the 2 strategies for sensorimotor delay.

Answer 39

Intermittency - e.g. saccades Prediction

Question 40

What is anticipatory control?

Answer 40

The use of the forward model predicts sensory feedback Reducing time of delay

Question 41

When is feedback and feedforward control used together?

Answer 41

Feedforward to make quick movement Adjusted by later feedback

Question 42

Process of the observer model

Answer 42

Previous state estimate Forward dynamic model predicts current status Copy sent to higher level Forward sensory model predicts sensory feedback Difference determines gain Sensory based correction Final state

Question 43

What type of memory is a motor skill?

Answer 43

Procedural

Question 44

What are the 4 stages of force field adaptations?

Answer 44

Initial exposure Adaptation After effect

Question 45

What happens to movement with the loss of proprioception? (3)

Answer 45

The longer the arm was hidden the more deviated the movement and poor timing

Question 46

How are internal models maintained?

Answer 46

Generalisation and retrieval

Question 47

What did **Ghahranmnani** show in skill generalisation?

Answer 47

Mouse movement slightly different to the hand Learning Tested without visual feedback Used skills from learning

Question 48

What is an interference?

Answer 48

Learning must take place before contextual cue

Question 49

What is Sherrington's reflex hypothesis?

Answer 49

All movements are obtained by combining stretch reflexes, where the brain sets a desired length

Question 50

What is Merton's servo hypthesis?

Answer 50

Movement generated by altering setpoint of posture