240 likes | 405 Views
ACTIVE SENSING. Lecture 4: Motor systems III. Summary of Motor Systems I-II: Basic motor control loops. PID control. Present. q ’. q. Past. q ’’. Future. Negative feedback loop. Dq ’ (t+ D t) = -f [ Dq ’ ( t )] , f is monotonic increasing. Positive feedback loop.
E N D
ACTIVE SENSING Lecture 4: Motor systems III Motor systems
Summary of Motor Systems I-II:Basic motor control loops Motor systems
PID control Present q’ q Past q’’ Future Negative feedback loop Dq’(t+Dt) = -f [Dq’(t)] , f is monotonic increasing Positive feedback loop Dq’(t+Dt) = f [Dq’(t)] , f is monotonic increasing Motor systems
Motor neuron spindle q’ Knee joint The spinal loop (stretch reflex) Motor systems
The spinal loop (stretch reflex) Motor neuron KM -Ksq’ -KsKMq’ spindle Knee joint Ks q’ dt Motor systems
Pain reflex Positive or negative? What is the underlying circuit? Motor systems
Contact loop – negative or positive? What does it take to switch between negative and positive FB loops? Motor systems
Basic motor control of other sensory organs • visual • Vibrissal Motor systems
Motor control in the visual system • Eye movement (oculomotor control) • Vision (perceptual control) Motor systems
The extra-ocular muscles (EOMs) Motor systems From Bear’s Neuroscience text book
Axes of eye movement control Motor systems
Donder’s and Listing’s laws Valid when looking with the head fixed • Donder’s law states that the orientation of the eye when looking in a specific direction is always the same. • Listing's law specifies what this orientation is. • It refers to the axes (the bars protruding from the eyes) used to rotate from center to various eccentric positions. • Listing found that all these axes are confined to a common plane. • This plane is called Listing's plane. Motor systems
How does the system keep Listing’s plane? • Ocular mechanics? • Neuronal mechanisms? Motor systems
Special design of extra-ocular muscles Orbital pulleys system Motor systems
Demmer JL, Ann. N.Y. Acad. Sci. 956: 17-32 (2002) Motor systems
Demmer JL, Ann. N.Y. Acad. Sci. 956: 17-32 (2002) Motor systems
Demmer JL, Ann. N.Y. Acad. Sci. 956: 17-32 (2002) Motor systems
Demmer JL, Ann. N.Y. Acad. Sci. 956: 17-32 (2002) Motor systems
Special design of extra-ocular muscles proprioceptors Motor systems
Special design of extra-ocular muscles Proprioceptive loop Motor systems
Targets of proprioceptive info • EOM proprioceptors run with the motor fibers of the muscle nerves EOM -> Gasserian ganglion -> trigeminal nuclei (pars interpolaris and pars caudalis). EOM proprioceptive information -> • brain stem structures • the superior colliculus • Thalamic nuclei (LGN, LP, Pulvinar) • the cerebellum • cortical areas: 17,18, frontal cortex. Most of these structures are involved in either vision or oculomotorcontrol. Motor systems
Roles of visual proprioception • oculomotor control • binocular vision • spatial localisation Motor systems
Role of visual proprioception in spatial localization Motor systems P. BUISSERET, PHYSIOLOGICAL REVIEWS Vol. 75, No. 2, April 1995