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Information Processing in Motor Learning

Chapter 17

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Outline

Structure and function of the nervous system

Information processing and making decisions

Feedback in movement control

Factors affecting information processing

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Structure and Function of the Nervous System

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CNS

Control center

PNS

Connects CNS with the rest of

the body

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The Neuron and Its Function

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Neuron

Nerve cell

The fundamental functional and structural unit of the nervous system

Allows information to travel throughout the body to various destinations

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Receptive Segment

Transmissive Segment

Conductive Segment

Cell Body

Nodes of Ranvier

Myelin sheath

Motor end plate

Dendrites: receive message

Terminal ending on muscle: sends off message to adjacent neuron

Axon: transmits

message to terminal ending

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Myelin sheath: fatty covering or

insulator

Skipping of the impulse allowing faster

conduction

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Types of NeuronsAfferent neurons

Sensory

Carry signals to the brain

Efferent neurons

Motor

Carry signals from the brain

CNS tissue cross-section

Interneurons

Originate and terminate in CNS

Connect afferents and efferents in CNS

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Types of Neurons cont.

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The Neuron’s Function

Receptive segment (dendrites)– Receives continuous synaptic input

(chemical) from other neurons

Conductive segment (axon)– Conduction of neural information in the

form of nerve impulse (electrical)

Transmissive segment (axon terminals)– Converts electrical nerve impulse to

chemical form (neurotransmitter) and sends it off to synapse

Receptive

Transmissive

Conductive

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Neural Impulses Transport the information necessary for all activities

we carry out The language of the nervous system Relay of impulse within neuron:

Rest: polarization

Stimulus: depolarization

Membrane potential = -70 mV

Rest: polarization

Action Potential

Resting Potential

Stimulus

(mV)

+50

0

-50

-100

+40 mV

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The Synapse and Synaptic Transmission

OO OOO O

OO

OO

SYNAPSE

SYNAPTIC TRANSMISSION

•Differ in terms of :

•Neurotransmitter used (e.g., acetylcholine or Ach)

•General function (e.g., inhibitory vs.excitatory)

. : :.. …. …… …..:: : .

: .:.;. . .

NEUROTRANSMITTER

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“All-or-none” law– Synaptic transmission causes action potential when

its strength is above a minimum threshold level

– Below threshold level = NO action potential

– Action potential is always the same intensity regardless of the strength of synaptic transmission above the threshold level

– Action potential intensity remains constant along the nerve fibre

The Synapse and Synaptic Transmission

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Indication of Strength of stimulus

Refractory Period

ST

IMU

LU

S

Absolute Relative

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Information Processing and Making Decisions

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Input

Output

The Human

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Information-Processing Stages

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Stimulus-Identification Stage

•Sensing environmental information

•Exteroceptors

•Proprioceptors

•Representation of stimulus and its nature

SENSATION PERCEPTIO

N

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Response-Selection Stage •Translation from perception to a response in the form of a motor program

MP 09564

MP 00333

MP 04567

MP 13498

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Response-Programming Stage

•Organizing the selected movement

•Retrieve motor program

•Command correct muscles

•Choose appropriate force

•Choose appropriate timing, etc.Efferent nerves

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Feedback in Movement Control

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As we execute movements, the receptors in our bodies continually update the CNS about the nature of our actions

The efficiency of motor control by the information-processing system depends on feedback

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Coaching Instructions

•Watch the opponent

•Feel the ball

•Keep balanced

•Listen to teammates

Sensory Receptors

•Ears

•Eyes

•Proprioceptors

•Vestibular system

•Etc.

Central Processing

System Functions

•Perception

•Decision making

•Data storage and coding

•Transition to motor program

Effector System

•Biceps

•Quadriceps

•Abdominals

•Latissimus dorsi

Output

•Pivot

•Dribble

•Jump

•Shot

•Pass

Exteroceptive Feedback

•Error information

•Motivate

•Reinforce

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Closed-Loop Control

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Follows the idea that movements may be planned and adjusted by feedback even during a movement

This general closed-loop control process is self-regulating and will continue to maintain the desired movement of the performer

Key elements:– Feedback– Error detection– Error correction

Analogy: thermostat

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Input

Perception Stimulus

Identification

Senses

Response Selection and Programming

Response Execution

Motor Program

Muscles

Output Environment

Comparator (Reference

system)CNS

Executive

The stages of information processing

PNS Effector

The motor program and motor system

Error

Proprioceptive Feedback

Correction

Exteroceptive Feedback

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Advantages of the Closed-Loop System

New skills Activities requiring

precision and accuracy Allows adjustment

according to the situation Adds versatility to

movements

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Disadvantages of the Closed-Loop System

Rapid, discrete actions do not properly fall under closed-loop control

Demands attention and time– Feedback must pass through the

processing stage

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Open-Loop Control

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Describes control of automatic actions

Motor program defines the details of skilled action before the movement begins and without the influence of peripheral feedback

Movements may be structured in advance, enabling them to run off automatically when initiated

Two main components:– The executive– The effector

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•Chooses motor program

•Relays instruction

•Carries out specific instructions automatically

EXECUTIVE EFFECTOR

No Feedback

STIMULUS

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Advantages of the Open-Loop System

Fast and forceful movements can be produced without extensive conscious control

Attention can de diverted to other responses

Does not demand as much time because there is no feedback

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Disadvantages of the Open-Loop System

Not as effective in unstable and less predictable situations– Movements may not be determined

effectively in advance

Not effective in precise and complex actions

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Factors Affecting Information Processing

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Information Processing

Sensory Input Quality

Sensory Receptors

Relay

Reaction Time

Ability to Anticipate

Capacity to Concentrate

Arousal and Psychological

Readiness