CHAPTER 3 Motor Control and Motor Learning - …

1 28 CHAPTERM otor Control and Motor LearningINTRODUCTIONM otor abilities and skills are acquired during the process ofmotor development through Motor Control and motorlearning. Once a basic pattern of movement is established,it can be varied to suit the purpose of the task or the envi-ronmental situation in which the task is to take place. Earlymotor development displays a fairly predictable sequence ofskill acquisition through childhood. However, the ways inwhich these Motor abilities are used for function are highlyvariable. Individuals rarely perform the movement exactlythe same way every time. This variability must be part ofany model used to explain how posture and movement movement system must be able to adapt to thechanging demands of the individual mover and environ-ment in which the movement takes place.

2 The individualmover must be able to learn from prior movement experi-ences. Different theories of Motor Control emphasize differ-ent developmental aspects of posture and of postural Control and balance is embeddedin the development of Motor Control . Understanding therelationship among Motor Control , Motor Learning , andmotor development provides a valuable framework forunderstanding the treatment of individuals with neurologicdysfunction at any development is a product as well as a process. Theproducts of Motor development are the milestones of thedevelopmental sequence and the kinesiologic componentsof movement such as head and trunk Control necessary forthese Motor abilities. These products are discussed inChapter 4. The process of Motor development is the way inwhich those abilities emerge.

3 The process and the productare affected by many factors such as time (age), maturation(genes), adaptation (physical constraints), and development is the result of the interaction of theinnate or built-in species blueprint for posture and move-ment and the person s experiences with moving afforded bythe environment. Sensory input is needed for the mover tolearn about moving and the results of moving. Motor devel-opment is the combination of the nature of the mover andthe nurture of the environment. Part of the genetic blue-print for movement is the means to Control posture andmovement. Motor development, Motor Control , and motorlearning contribute to an ongoing process of changethroughout the life span of every person who CONTROLM otor Control ,the ability to maintain and change postureand movement, is the result of a complex set of neurologicand mechanical processes.

4 Those processes include Motor ,cognitive, and perceptual development. The developmentof Motor Control begins with the Control of self movements,and proceeds to the Control of movements in relationshipto changing conditions (VanSant, 1995). Control of self-movement largely results from the development of the neu-romotor systems. As the nervous and muscular systemsmature, movement emerges. Motor controlallows the nerv-ous system to direct what muscles should be used, in whatorder, and how quickly, to solve a movement problem. Theinfant s first movement problem relates to overcoming theeffect of gravity. A second but related problem is how tomove a larger head as compared with a smaller body toestablish head Control . Later, movement problems arerelated to controlling the interaction between stability andmobility of the head, trunk, and limbs.

5 Control of task-spe-cific movementssuch as stringing beads or riding a tricycle3 OBJECTIVESA fter reading this CHAPTER , the student will be able Motor Control and Motor the relationship among Motor Control , Motor Learning , and Motor between the hierarchic and systems models of Motor the development of postural Control and the role of experience and feedback in Motor Control and Motor Motor Control and Motor Learning theories to therapeutic on cognitive and perceptual abilities. The task tobe carried out by the person within the environmentdictates the type of movement solution that is going to the Motor abilities of a person change over time,the Motor solutions to a given Motor problem may alsochange. The motivation of the individual to move may alsochange over time and may affect the intricacy of the move-ment solution.

6 An infant encountering a set of stairs sees atoy on the top stair. The infant creeps up the stairs but thenhas to figure out how to get down: cry for help, bump downon the buttocks, creep down backward, or even attemptcreeping down forward. A toddler faced with the samedilemma may walk up the same set of stairs one step at atime holding onto a railing, and descend in a sitting fashionholding the toy, or may be able to hold the toy with onehand and the railing with the other and descend the sameway as walking up the stairs. The child will walk up anddown without holding on, and an even older child may runup those same stairs. The relationship among the task, theindividual, and the environment is depicted graphically inFigure 3-1. All three components must be considered whenthinking about Motor Control Time FrameMotor controlhappens not in the space of days or weeks, asis seen in Motor development, but in fractions of 3-2 illustrates a comparison of time frames associatedwith Motor Control , Motor Learning , and Motor controloccurs because of physiologic processesthat happen at cellular, tissue, and organ levels.

7 Physiologicprocesses have to happen quickly to produce timely andefficient movement. What good does it do if you extend anoutstretched arm after having fallen down? Extending yourarm in a protective response has to be quick enough to beuseful, that is, to break the fall. Individuals with nervoussystem disease may exhibit the correct movement pattern,but they have impaired timing, producing the movementtoo slowly to be functional, or they have impaired sequenc-ing of muscle activation, producing a muscle contraction atthe wrong time. Both of these problems, impaired timingand impaired sequencing, are examples of deficits in of Sensation in Motor ControlSensory information plays an important role in motorcontrol. Initially, sensation cues reflexive movements inwhich few cognitive or perceptual abilities are needed.

8 Asensory stimulus produces a reflexive Motor the lip of a newborn produces head turning,whereas stroking a newborn s outstretched leg produceswithdrawal. Sensation is an ever-present cue for motorbehavior in the seemingly reflex-dominated infant. As vol-untary movement emerges during Motor development,sensation provides feedback accuracy for hand placementduring reaching and later for creeping. Sensation fromweight bearing reinforces maintenance of developmentalpostures such as the prone on elbows position and thehands and knees position. Sensory information is crucialto the mover when interacting with objects and maneu-vering within an environment. Figure 3-3 depicts how sen-sation provides the necessary feedback for the body toknow whether a task such as reaching or walking was per-formed and how well it was of Motor ControlMany theories of Motor Control have been posited, butonly those most closely related to early Motor developmentare discussed in this CHAPTER .

9 The first theoretic model ofmotor Control presented is the traditional hierarchic , a systems model of Motor Control is Control and Motor Learning CHAPTER 329 MOTORCONTROLFIGURE Control emerges from an interactionbetween the task, the individual, and the environment. (FromShumway-Cook A, Woollacott MH. Motor Control : Theory andPractical Applications, 2nd edition. Baltimore, LippincottWilliams & Wilkins, 2001.)DevelopmentLearningControlMillisec ondsHours, days, weeksMonths, years, decadesFIGURE scales of interest from a Motor Control , Motor Learning , and Motor development perspective. (From CechD, Martin S. Functional Movement Development Across the LifeSpan, 2nd edition. Philadelphia, WB Saunders, 2002.)Hierarchic TheoryMany theories of Motor Control exist, but the most tradi-tional one is that of a hierarchy.

10 Characteristics of a hierar-chic model of Motor Control include a top-downperspective. The cortex of the brain is seen as the highestlevel of Control , with all subcortical structures taking ordersfrom it. The cortex can and does direct movement. A per-son can generate an idea about moving in a certain way andthe nervous system carries out the command. The ultimatelevel of Motor Control , voluntary movement,is achieved bymaturation of the the hierarchic model, a relationship exists between thematuration of the developing brain and the emergence ofmotor behaviors seen in infancy. One of the ways in whichnervous system maturation has been routinely gauged is bythe assessment of reflexes. The reflex is seen as the basic unitof movement in this Motor Control model. Movement isacquired from the chaining together of reflexes and reac-tions.