One should beware of mathematicians and all who make empty prophecies. The danger already exists that the mathematicians have made a covenant with the devil to darken the spirit and confine man in the bonds of hell St Augustine, Bishop of Hippo, circa 400 A D To move things is all that mankind can do. For such the sole executant is muscle, whether in whispering a syllable or in felling a forest Charles sherington. 1924 Optimization principles in motor Control
“One should beware of mathematicians and all who make empty prophecies. The danger already exists that the mathematicians have made a covenant with the devil to darken the spirit and confine man in the bonds of Hell” St Augustine, Bishop of Hippo, circa 400 A.D “To move things is all that Mankind can do…For such the sole executant is muscle, whether in whispering a syllable or in felling a forest” Charles Sherington, 1924 Optimization Principles in Motor Control 1
Optimization principles in motor control Prof Dava J. Newman Joseph h. saleh Department of Aeronautics and Astronautics Massachusetts Institute of Technology Optimization principles in motor Control
Optimization Principles in Motor Control Prof. Dava J. Newman Joseph H. Saleh Depart m ent of Aer onau tic s a n d Astr o nautics Ma s s achus e tts I n stitu te of T echnology O ptimization Princi ples in M otor Co ntrol 2
Outline Review of muscle contraction From ap generation to contraction of fibers Muscle proprioceptors(spindles and Golgi tendons) Afferent and efferent axons The Muscle simulink model Reflections on models Optimization Principles in Motor Control Understanding the fundamental question in biomechanics Are all motor behavior optimal in some sense? Kinematic versus dynamic objective functions Pre-Programmed Muscle Response During Downward Jumps Optimization principles in motor Control
Outline • Review of Muscle Contraction – From AP generation to contraction of fibers – Muscle proprioceptors (spindles and Golgi tendons) – Afferent and efferent axons • The Muscle Simulink model • Reflections on Models • Optimization Principles in Motor Control – Understanding the fundamental question in biomechanics – Are all motor behavior optimal in some sense? – Kinematic versus dynamic objective functions • Pre-Programmed Muscle Response During Downward Jumps Optimization Principles in Motor Control 3
Muscles: Effectors of the Motor System The major output of the elaborate information processing that takes place in our brain is the generation of a contractile force in our skeletal muscles Muscle fasciculus Muscle fiber MyO Sarcomere Each muscle fiber is innervated by only one motor neuron, although each motor neuron innervates a number of muscle fibers The motor neuron and all the fibers it innervates is called a motor unit (the smallest functional unit controlled by the motor system) Optimization principles in motor Control
Muscles: Effectors of the Motor System • The major output of the elaborate i nformation processing that takes place in o ur brai n i s the g e n erati o n of a con tractile force in our skeletal muscles. • Muscl e fasci c u lus – Muscle fib er • M y o fib ril – Sarcom ere • Each muscle fib e r is i n n ervated b y only one m otor neuro n, although each m otor n euron i n n ervates a numb e r of muscl e fib e rs • The m o t or ne u r on and al l the fiber s i t inne rvates i s cal l ed a m o t or u nit (the smal l est functional uni t contr o l l ed by the m o t o r system) O ptimization Princi ples in M otor Co ntrol 4
Muscles: Effectors of the Motor system The number of muscle fibers innervated by one motor neuron is called the innervation ratio the innervation ratio can vary between 10 and 2000 a low innervation ratio indicates a greater capacity for finely grading the muscle total force Optimization Principles in Motor Control
Muscles: Effectors of the Motor System • The number of muscle fibers innervated by one motor neuron is called the innervation ratio. The innervation ratio can vary between 10 and 2000 • A low innervation ratio indicates a g reater capacity for finely g rading the muscle total force O ptimization Princi ples in M otor Co ntrol 5