lecture 5

Question 1

motor control definition

Answer 1

defined as the study of the systems/mechanisms that control posture, movements or skills of the human perceptual-motor system.

Question 2

open-loop control

Answer 2

input - executive - effector.
movements executive sends a command (i.e., movement plan) to the effectors, no use of sensory information to guide movements. typically, movements shorter than 150-200ms use open loop control.

Question 3

closed-loop control

Answer 3

input - executive - effector
(sensory feedback from effector to inout)

the executive uses sensory information as a comparison tool to amend motor commands (if needed). movements longer than 200ms and movements that require precision use closed loop control.

Question 4

Plato thoughts on motor control

Answer 4

linked movement to chariot movement by horses. first guy to talk about motor control.

Question 5

Aristotle thoughts on motor control.

Answer 5

student of Plato, arguably first to pay attention to coordination of movement. Mover (soul) is not observable but the moving body is. The gods would give us the ability to do what we needed to do.

Question 6

Galen ancient thoughts on motor control

Answer 6

we are guided by animal spirits to coordinate our behaviour. idea of antagonist and agonist pairs.

Question 7

who was the first scientist to draw the human body

Answer 7

Da Vinci (vitruvian man)

Question 8

Rene Descartes

Answer 8

Formalised Cartesian duality (soul and body are two independent matters). Soul controlled our body. Recognised that some reflexes are independent from the soul. “I think, therefore I am”.

Question 9

Giovanni Borell

Answer 9

Father of biomechanics.
Estimated max forces by muscles. Mechanics of jumping. Nerve juices that enabled us to move.
Chemical energy that is used for energy, started to look at what powered our muscles.

Question 10

Eduard Pflüger (1829–1910)

Answer 10

Frog guy - frog without a head will still wipe away the acid from its back. (reflexes enable movements to incur).
Spinal control of movements.

Question 11

reflex theory

Answer 11

reflex form all basis of movements (Sherrington). Complex movements are just response chaining or reflex chaining.
Received info from the environment that allow some kind of reflex to incur.

Question 12

Limitation of the reflex theory.

Answer 12

does not allow for proactive action (predictive movements). poor account of open loop control.
some movements do not require sensory information.

Question 13

6 points of Hierarchical theories of movement control.

Answer 13

Our human body system is organised in a hierarchy.
Higher CNS = voluntary actions.
Lower CNS = more automatic actions (e.g., reflexes).
Peripheral nervous system (PNS) – sensory feedback.
Controller = cerebral cortex (i.e., top down control).
Perceive - decide - act.

Question 14

what does the hierarchical theory assume.

Answer 14

Assumes ALL aspects of voluntary movement planning and execution are the sole responsibility of the higher cortical centres.

Question 15

Generalised Motor Programme (GMP) (Schmidt, 1975)

Answer 15

idea is that the CNS organises and controls movement by generating a set of general motor programmes that can be adpated and modified to produce a variety of specific movements.

Question 16

two types of parameters for GMPs

Answer 16

1) Invariant parameters i. Relative sequencing of sub-movements ii. Relative timing iii. Relative forces

2) Variant parameters i. Specific motor units ii. Absolute timing iii. Absolute forces

Question 17

Schemas

Answer 17

Recall schemas provide the scale of parameters for action

Question 18

Motor response schema

Answer 18

relationship between motor response and outcome

Question 19

Recognition schema

Answer 19

relationship between sensory experience and outcome

Question 20

Limitations of hierarchical theories

Answer 20

Cannot explain how direct perception works: ? Optical flow ? Affordances ? “Time-to-contact”
Cannot explain self-organizing systems ? Hysteresis

Question 21

Dynamical/Ecological theories of motor control

Answer 21

Important foundational contributors to and assumptions of dynamical/ecological systems approaches

Question 22

contributors of the Dynamical/Ecological theories of motor control.

Answer 22

Gibson (1966) – cf. ecological psychology ✓ Direct perception ✓ Affordances

Bernstein (1967) – cf. physiology, mechanics ✓ degrees of freedom problem ✓ coordinative structures

Question 23

3 Assumptions about human movement control and perception

Answer 23

Human movement control is complex and dynamic.”

“The human perceptual-motor system is capable of self-organizing via interacting constraints.”

“Perception of affordances (opportunities for action) is direct, facilitated by energy flows (e.g., light, sound) from the environment, without intermediary processing in the brain.

Question 24

D/E: Perceptual-motor landscape

Answer 24

a manifold of all the possible movement possibilities available to an individual.

Question 25

D/E: Self-organisation

Answer 25

natural tendency for the human perceptual motor system to settle into attractors.

Question 26

D/E: Attractors

Answer 26

stable and functional patterns of organisations exhibited by the human perceptual motor system.

Question 27

D/E: Order parameters

Answer 27

collective behaviour of the system’s many components e.g., relative phase between body segments.

Question 28

D/E: Control parameters

Answer 28

A parameter of internal or external origin that when manipulated controls the system in a nonspecific fashion, e.g., frequency, velocity.

Question 29

D/E: Stability/instability

Answer 29

a qualitative state describing the tendency of a system to remain in a particular pattern of organisation, or not.

Question 30

D/E: Hysteresis

Answer 30

the tendency to remain in the current basin of attraction as the control parameter (e.g., velocity) is increased (or decreased).

Question 31

optical flow

Answer 31

patterns of apparent motion of objects caused by relative motion of the observer and a scene. This phenomenon is a form of direct perception and is important for affordance perception, as it provides information about the environment’s spatial layout and opportunities for action