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Unformatted text preview: Motor Control Theories Ch 5 Part 1 Regulation and control of skills How do we coordinate the many muscles and joints necessary to perform a task. How do we choose between the wide variety of combinations of components available to perform a task. How do we choose order of movement segments needed to perform a task. What is a theory It must accurately describe a large class of observations o A theory is build on a large number of experiments or observations which are logically related to each other. It must make definite predictions about the results of future (unobserved) observations o Predictions made by a theory can be tested. o A theory can be disproved by experimental evidence. Motor Control Theory Describes and explains how the nervous system produces coordinated movement of motor skill in a variety of environments Two important terms: o Coordination o The degrees of freedom problem Coordination Coordination is the patterning of head, body, and limb movements relative to the patterning of environmental objects and events (Turvey, 1990) Two parts to consider: o Movement pattern of a skill in relation to a specific point of time o Context of the environment of the head, body, and/or limb movements so the actions can be accomplished Degrees of Freedom Degrees of freedom are the number of independent components that specify completely the number of ways that the elements in the system can act. Degrees of freedom problem is the question how does the nervous system control the many muscles and joints involved in producing a complex pattern. 1 Control systems There are two basic systems of control o Closed-loop control system o Open-loop control system Closed-loop control system o Closed-loop control (conscious) Control of movement involving feedback and error detection and correction. Loop completed from Executive (decisions) to Effector (carries out the decisions) to Feedback (information about the state of the system) to Comparator (detects errors/discrepancies) to Executive o Compensation (unconscious closed-loop control) Reflexes, involuntary, rapid responses to stimuli Low level processes in spinal cord M1 response (Monosynaptic reflex) o Occurs 30-50 ms after added load o Brief, short distance M2 response (Functional stretch/long loop reflex Polysynaptic) o Occurs 50-80 ms after added load o Larger EMG force, longer duration Triggered reaction Occurs 80-120 ms after added load (too fast to be voluntary) Can be learned Voluntary Reaction time response (M3 response) 3 rd burst of EMG, Powerful and sustained Modified by instructions, anticipation, etc Requires attention Open-loop control o Instructions for the movement are determined in advance o No feedback is used during movement o Initiated in an all-or-none fashion o Action takes care of itself What is different from closed-loop control?...
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This note was uploaded on 06/01/2011 for the course KIN 3513 taught by Professor Porter during the Spring '08 term at LSU.
- Spring '08