Motor Systems

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Motor Systems

• BCS 9.011
• Fall 2006
• M. Fee

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Structure of Muscle Fiber
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Sliding Filament Model
Andrew Huxley, Hugh Huxley, 1954
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Actin-Myosin Interaction During Contraction
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Isometric Force vs Muscle Fiber Length
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Voluntary movement
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Slow and Fast Motor Units
Desmedt and Godaux, 1977
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Fast motor units produce larger force
Fast
Slow
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Muscle Twitch Properties
Sag
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Isometric force ramp
Desmedt and Godaux, 1977
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Firing Rate and Recruitment
Monster and Chan, 1977
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Motor Systems

• BCS 9.011
• Fall 2006
• M. Fee

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Muscle Receptors
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Golgi Tendon Organ
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Type Ia and II afferent responses to muscle
stretch
Type Ia
Type II
Matthews, 1964, 1972
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Stretch Reflex
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Force feedback step response
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Ia activity during voluntary finger movement
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Frog wiping reflex
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Obstacle avoidance in wiping reflex
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Oscillatory Spinal Dynamics in Locomoting
Decerebrate Cat
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Gait Changes in Cat Locomotion
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Gait Changes in Cat Locomotion
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Locomotion in Decerebrate Cat
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(No Transcript)
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Neurons in primary motor cortex (M1) code for
direction of arm movement
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M1 neurons participate in a range of movement
directions
Preferred Direction
Different M1 neurons have different preferred
directions M1 neurons cooperate to code for
movements as a population population coding