chapter 6
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Chapter 6Chapter 6
Touch, Proprioception and Touch, Proprioception and VisionVision
Concept: Touch, proprioception and vision are important components of motor control
IntroductionIntroduction
Sensory information is essential for all theories Sensory information is essential for all theories of motor control and learningof motor control and learning
–Provides pre-movement information Provides pre-movement information –Provides feedback about the movement in progressProvides feedback about the movement in progress–Provides post-movement information about action Provides post-movement information about action
goal achievementgoal achievement
Focus of current chapter is three types of Focus of current chapter is three types of sensory informationsensory information
–Touch, vision, and proprioceptionTouch, vision, and proprioception
Touch and Motor ControlTouch and Motor Control
Describe some ways we use touch to help Describe some ways we use touch to help us achieve action goalsus achieve action goals
Neural basis of touch Neural basis of touch [[see Fig. 6.1see Fig. 6.1]]
–Skin receptorsSkin receptorsMechanoreceptors located in the dermis layer of Mechanoreceptors located in the dermis layer of
skinskin
Greatest concentration in finger tipsGreatest concentration in finger tips
Provide CNS with temperature, pain, and Provide CNS with temperature, pain, and movement info movement info
Touch and Motor Control, Touch and Motor Control, cont’dcont’d
Typical research Typical research techniquetechnique
–Compare performance Compare performance of task involving finger(s) of task involving finger(s) before and after before and after anesthetizing finger(s)anesthetizing finger(s)
Research shows tactile Research shows tactile sensory info influencessensory info influences::
–Movement accuracyMovement accuracy
–Movement consistencyMovement consistency
–Movement force adjustmentsMovement force adjustments
Roles of Tactile Info in Motor Control
See an example of research for typing – A Closer Look, p. 109
Proprioception and Motor ControlProprioception and Motor Control
Proprioception:Proprioception: The sensory system’s The sensory system’s detection and reception of movement detection and reception of movement and spatial position of limbs, trunk, and and spatial position of limbs, trunk, and headhead
–We will use the term synonymously with We will use the term synonymously with the term “kinesthesis”the term “kinesthesis”
Neural Basis of ProprioceptionNeural Basis of Proprioception
CNS receives proprioception information from CNS receives proprioception information from sensory neural pathways that begin in sensory neural pathways that begin in specialized sensory neurons known as specialized sensory neurons known as proprioceptorsproprioceptors
–Located in muscles, tendons, ligaments, and jointsLocated in muscles, tendons, ligaments, and joints
Three primary types of proprioceptorsThree primary types of proprioceptors–Muscle spindlesMuscle spindles–Golgi tendon organsGolgi tendon organs–Joint receptorsJoint receptors
Neural Basis of Proprioception: Neural Basis of Proprioception: ProprioceptorsProprioceptors1.1. Muscle spindlesMuscle spindles
In most skeletal muscles in a capsule of specialized In most skeletal muscles in a capsule of specialized muscle fibers and sensory neuronsmuscle fibers and sensory neurons
–Intrafusal fibers Intrafusal fibers [[see Fig. 6.2see Fig. 6.2]]–Lie in parallel with extrafusal muscle fibersLie in parallel with extrafusal muscle fibers
Mechanoreceptors that detect changes in muscle fiber Mechanoreceptors that detect changes in muscle fiber length (i.e. stretch) and velocity (i.e. speed of stretch)length (i.e. stretch) and velocity (i.e. speed of stretch)
–Enables detection of changes in joint angleEnables detection of changes in joint angle
Function as a feedback mechanism to CNS to maintain Function as a feedback mechanism to CNS to maintain intended limb movement position, direction, and velocityintended limb movement position, direction, and velocity
Neural Basis of Proprioception: Neural Basis of Proprioception: Proprioceptors, cont’dProprioceptors, cont’d
2.2. Golgi-Tendon Organs Golgi-Tendon Organs (GTO)(GTO)
In skeletal muscle near In skeletal muscle near insertion of tendoninsertion of tendon
Detect changes in muscle Detect changes in muscle tension (i.e. force)tension (i.e. force)
–Poor detectors of muscle Poor detectors of muscle length changeslength changes
3.3. Joint ReceptorsJoint Receptors
Several types located in Several types located in joint capsule and joint capsule and ligamentsligaments
Mechanoreceptors that Mechanoreceptors that detect changes in detect changes in
–Force and rotation Force and rotation applied to the joint, applied to the joint,
– Joint movement angle, Joint movement angle, especially at the extreme especially at the extreme limits of angular movement limits of angular movement or joint positions or joint positions
Techniques to Investigate the Role Techniques to Investigate the Role of Propioception in Motor Controlof Propioception in Motor Control
Deafferentation techniquesDeafferentation techniquesSurgical deafferentationSurgical deafferentation
–Afferent neutral pathways associated with movements of Afferent neutral pathways associated with movements of interest have been surgically removed or alteredinterest have been surgically removed or altered
Deafferentation due to sensory neuropathyDeafferentation due to sensory neuropathy–Sometimes called “peripheral neuropathy” Sometimes called “peripheral neuropathy” –Large myelinated fibers of the limb are lost, leading to a loss of Large myelinated fibers of the limb are lost, leading to a loss of
all sensory information except pain and temperatureall sensory information except pain and temperature
Temporary deafferentationTemporary deafferentation–““Nerve block technique” – Inflate blood-pressure cuff to create Nerve block technique” – Inflate blood-pressure cuff to create
temporary disuse of sensory nerves temporary disuse of sensory nerves
Techniques to Investigate the Role of Techniques to Investigate the Role of Propioception in Motor Control, cont’dPropioception in Motor Control, cont’d
Tendon vibration techniqueTendon vibration technique–Involves high speed vibration of the tendon Involves high speed vibration of the tendon
of the agonist muscleof the agonist muscle–Proprioceptive feedback is distorted rather Proprioceptive feedback is distorted rather
than removedthan removed
Role of Proprioceptive Role of Proprioceptive Feedback in Motor ControlFeedback in Motor ControlResearch using the deafferentation and tendon vibration Research using the deafferentation and tendon vibration
techniques has demonstrated that proprioception techniques has demonstrated that proprioception influences:influences: Movement accuracy Movement accuracy
–Target accuracyTarget accuracy–Spatial and temporal accuracy for movement in progressSpatial and temporal accuracy for movement in progress
Timing of onset of motor commandsTiming of onset of motor commands
Coordination of body and/or limb segmentsCoordination of body and/or limb segments–Postural controlPostural control–Spatial-temporal coupling between limbs and limb segmentsSpatial-temporal coupling between limbs and limb segments–Adapting to new situations requiring non-preferred movement Adapting to new situations requiring non-preferred movement
coordination patternscoordination patterns
Vision and Motor ControlVision and Motor Control
Vision is our preferred source of sensory Vision is our preferred source of sensory informationinformation
Evidence from everyday experiencesEvidence from everyday experiences–Beginning typists look at their fingersBeginning typists look at their fingers–Beginning dancers look at their feetBeginning dancers look at their feet
Evidence from researchEvidence from research–The classic “moving room experiment”The classic “moving room experiment”
The Moving Room ExperimentThe Moving Room Experiment
Lee & Aronson (1974)Lee & Aronson (1974) Participants stood in a room in Participants stood in a room in
which the walls moved toward which the walls moved toward or away from them but floor did or away from them but floor did not movenot move
Situation created a conflict Situation created a conflict between which two sensory between which two sensory systems?systems?
Vision & proprioceptionVision & proprioception
ResultsResults When the walls moved, When the walls moved,
people adjusted their people adjusted their posture to not fall, even posture to not fall, even though they weren’t though they weren’t moving off balancemoving off balance
WHY?WHY?
Neurophysiology of VisionNeurophysiology of Vision
Basic Anatomy of the EyeBasic Anatomy of the Eye
See Figure 6.6 for the following anatomical See Figure 6.6 for the following anatomical componentscomponents
–CorneaCornea–IrisIris–LensLens–ScleraSclera–Aqueous humorAqueous humor–Vitreous humorVitreous humor
Neurophysiology of Vision, Neurophysiology of Vision, cont’dcont’dNeural Components of the Eye and VisionNeural Components of the Eye and Vision
Retina Retina [[see Fig. 6.6see Fig. 6.6]]
–Fovea centralisFovea centralis–Optic diskOptic disk–RodsRods–ConesCones
Optic nerve (cranial nerve II) Optic nerve (cranial nerve II) [[Fig. 6.7Fig. 6.7]]
–From the retina to the brain’s visual cortexFrom the retina to the brain’s visual cortex
Techniques for Invesigating the Techniques for Invesigating the Role of Vision in Motor ControlRole of Vision in Motor Control
Eye movment recordingEye movment recording–Tracks foveal vision’s “point of gaze”Tracks foveal vision’s “point of gaze”
i.e. “what” the person is looking at i.e. “what” the person is looking at
Temporal occlusion techniquesTemporal occlusion techniques–Stop video or film at various timesStop video or film at various times–Spectacles with liquid crystal lensesSpectacles with liquid crystal lenses
Event occlusion techniqueEvent occlusion technique–Mask view on video or film of specific events or Mask view on video or film of specific events or
characteristicscharacteristics
Role of Vision in Motor ControlRole of Vision in Motor Control
Evidence comes from research investigating Evidence comes from research investigating specific issues and vision characteristics:specific issues and vision characteristics:
1.1. Monocular vs. Binocular VisionMonocular vs. Binocular Vision
Binocular vision important for Binocular vision important for depth-perceptiondepth-perception when 3-dimensional features involved in when 3-dimensional features involved in performance situation, e.g. performance situation, e.g.
–Reaching – grasping objectsReaching – grasping objects–Walking on a cluttered pathwayWalking on a cluttered pathway–Intercepting a moving object Intercepting a moving object
Role of Vision in Motor Control, Role of Vision in Motor Control, cont’d.cont’d.2.2. Central and Peripheral VisionCentral and Peripheral Vision
Central visionCentral vision–Sometimes called foveal visionSometimes called foveal vision
Middle 2-5 deg. of visual fieldMiddle 2-5 deg. of visual field
–Provides specific information to allow us to achieve Provides specific information to allow us to achieve action goals, e.g.action goals, e.g.
For reaching and grasping an objectFor reaching and grasping an object – specific – specific characteristic info, e.g. size, shape, required to prepare, move, characteristic info, e.g. size, shape, required to prepare, move, and grasp objectand grasp object
For walking on a pathwayFor walking on a pathway – specific pathway info needed to – specific pathway info needed to stay on the pathwaystay on the pathway
Role of Vision in Motor Control, Role of Vision in Motor Control, cont’d.cont’d.
2.2. Central and Peripheral Vision, cont’dCentral and Peripheral Vision, cont’d..Peripheral visionPeripheral vision
–Detects info beyond the central vision limitsDetects info beyond the central vision limitsUpper limit typically ~ 200 deg.Upper limit typically ~ 200 deg.
–Provides info about the environmental context and Provides info about the environmental context and the moving limb(s)the moving limb(s)
–When we move through an environment, peripheral When we move through an environment, peripheral vision detects info by assessing vision detects info by assessing optical flow patternsoptical flow patterns
Optical flow =Optical flow = rays of light that strike the retina rays of light that strike the retina
Role of Vision in Motor Control, Role of Vision in Motor Control, cont’d.cont’d.
2.2. Central and Peripheral Vision, cont’dCentral and Peripheral Vision, cont’dTwo visual systemsTwo visual systems
–Vision for perception (Vision for perception (central visioncentral vision))Anatomically referred to as the Anatomically referred to as the ventral streamventral stream – – from visual from visual
cortex to temporal lobecortex to temporal lobe
For fine analysis of a scene, e.g. form, featuresFor fine analysis of a scene, e.g. form, features
Typically available to consciousnessTypically available to consciousness
–Vision for action (Vision for action (peripheral visionperipheral vision))Anatomically referred to as the Anatomically referred to as the dorsal streamdorsal stream – – from visual from visual
cortex to posterior parietal lobecortex to posterior parietal lobe
For detecting spatial characteristics of a scene and guiding For detecting spatial characteristics of a scene and guiding movementmovement
Typically not available to consciousnessTypically not available to consciousness
Role of Vision in Motor Control, Role of Vision in Motor Control, cont’d.cont’d.3.3. Perception – Action CouplingPerception – Action Coupling
As discussed in ch. 5, refers to the “coupling” (i.e. As discussed in ch. 5, refers to the “coupling” (i.e. linking together) of a perceptual event and an linking together) of a perceptual event and an actionaction
Example of research evidence:Example of research evidence:–See experiments by Helsen et al. (1998 & 2000) See experiments by Helsen et al. (1998 & 2000)
described in textbook (pp.127 – 128)described in textbook (pp.127 – 128)
–Results show that spatial and temporal Results show that spatial and temporal characteristics of limb movements occurred together with characteristics of limb movements occurred together with specific spatial and temporal characteristics of eye specific spatial and temporal characteristics of eye movementsmovements
Role of Vision in Motor Control, Role of Vision in Motor Control, cont’d.cont’d.4.4. Amount of Time Needed for Movement Amount of Time Needed for Movement
Corrections?Corrections?Concerns vision’s feedback role during movementConcerns vision’s feedback role during movement
Researchers have tried to answer this question since Researchers have tried to answer this question since original work by Woodworth in 1899original work by Woodworth in 1899
Typical procedure:Typical procedure: Compare accuracy of rapid manual Compare accuracy of rapid manual aiming movements of various MTs with target visible and aiming movements of various MTs with target visible and then not visible just after movement beginsthen not visible just after movement begins
–Expect accurate movement with lights off when no visual Expect accurate movement with lights off when no visual feedback needed during movement feedback needed during movement
–Currently, best estimate is a Currently, best estimate is a range of 100 – 160 msec.range of 100 – 160 msec. (The (The typical range for simple RT to a visual signal)typical range for simple RT to a visual signal)
Role of Vision in Motor Control, Role of Vision in Motor Control, cont’d.cont’d.5.5. Time-to-Contact: The Optical Variable Time-to-Contact: The Optical Variable tautau
Concerns situations in whichConcerns situations in which–Object moving to person must be interceptObject moving to person must be intercept–Person moving toward object needs to contact or avoid contact Person moving toward object needs to contact or avoid contact
with objectwith object
Vision provides info about time-to-contact object which Vision provides info about time-to-contact object which motor control system uses to initiate movementmotor control system uses to initiate movement
–Automatic, non-conscious specification based on changing size Automatic, non-conscious specification based on changing size of object on retinaof object on retina
–At critical size, requisite movement initiatedAt critical size, requisite movement initiated
David Lee (1974) showed the time-to-contact info David Lee (1974) showed the time-to-contact info specified by an optical variable (specified by an optical variable (tautau), which could be ), which could be mathematically quantifiedmathematically quantifiedMotor control benefit –Motor control benefit – Automatic movement initiation Automatic movement initiation
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