©2007 McGraw-Hill Higher Education. All rights reserved Chapter 6 Touch, Proprioception and Vision Concept: Touch, proprioception and vision are important components of motor control
Jan 20, 2016
©2007 McGraw-Hill Higher
Education. All rights reserved
Chapter 6Chapter 6
Touch, Proprioception and Vision
Concept: Touch, proprioception and vision are important components of motor control
©2007 McGraw-Hill Higher
Education. All rights reserved
IntroductionIntroduction
Sensory information is essential for all theories of motor control and learning
•Provides pre-movement information •Provides feedback about the movement in
progress•Provides post-movement information
about action goal achievement Focus of current chapter is three types
of sensory information•Touch, vision, and proprioception
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Touch and Motor ControlTouch and Motor Control
Describe some ways we use touch to help us achieve action goals
Neural basis of touch [see Fig. 6.1]•Skin receptors
Mechanoreceptors located in the dermis layer of skin
Greatest concentration in finger tipsProvide CNS with temperature, pain,
and movement info
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Touch and Motor Control, cont’dTouch and Motor Control, cont’d
Typical research technique
•Compare performance of task involving finger(s) before and after anesthetizing finger(s)
Research shows tactile sensory info influences:
•Movement accuracy•Movement consistency•Movement force
adjustments
Roles of Tactile Info in Motor Control
See an example of research for typing – A Closer Look, p. 109
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Proprioception andMotor ControlProprioception andMotor Control
Proprioception: The sensory system’s detection and reception of movement and spatial position of limbs, trunk, and head
•We will use the term synonymously with the term “kinesthesis”
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Neural Basis of ProprioceptionNeural Basis of Proprioception
CNS receives proprioception information from sensory neural pathways that begin in specialized sensory neurons known as proprioceptors
•Located in muscles, tendons, ligaments, and joints
Three primary types of proprioceptors•Muscle spindles•Golgi tendon organs•Joint receptors
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Neural Basis of Proprioception: ProprioceptorsNeural Basis of Proprioception: Proprioceptors
1. Muscle spindles In most skeletal muscles in a capsule of
specialized muscle fibers and sensory neurons•Intrafusal fibers [see Fig. 6.2]•Lie in parallel with extrafusal muscle fibers
Mechanoreceptors that detect changes in muscle fiber length (i.e. stretch) and velocity (i.e. speed of stretch)
•Enables detection of changes in joint angle Function as a feedback mechanism to CNS to
maintain intended limb movement position, direction, and velocity
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Neural Basis of Proprioception: Proprioceptors, cont’dNeural Basis of Proprioception: Proprioceptors, cont’d
2. Golgi-Tendon Organs (GTO)
In skeletal muscle near insertion of tendon
Detect changes in muscle tension (i.e. force)
•Poor detectors of muscle length changes
3. Joint Receptors Several types located
in joint capsule and ligaments
Mechanoreceptors that detect changes in
•Force and rotation applied to the joint,
• Joint movement angle, especially at the extreme limits of angular movement or joint positions
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Techniques to Investigate the Role of Propioception in Motor ControlTechniques to Investigate the Role of Propioception in Motor Control
Deafferentation techniques Surgical deafferentation
•Afferent neutral pathways associated with movements of interest have been surgically removed or altered
Deafferentation due to sensory neuropathy•Sometimes called “peripheral neuropathy” •Large myelinated fibers of the limb are lost, leading
to a loss of all sensory information except pain and temperature
Temporary deafferentation•“Nerve block technique” – Inflate blood-pressure
cuff to create temporary disuse of sensory nerves
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Techniques to Investigate the Role of Propioception in Motor Control, cont’dTechniques to Investigate the Role of Propioception in Motor Control, cont’d
Tendon vibration technique•Involves high speed vibration of the
tendon of the agonist muscle•Proprioceptive feedback is distorted
rather than removed
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Role of Proprioceptive Feedback in Motor ControlRole of Proprioceptive Feedback in Motor Control
Research using the deafferentation and tendon vibration techniques has demonstrated that proprioception influences:
Movement accuracy •Target accuracy•Spatial and temporal accuracy for movement in progress
Timing of onset of motor commands Coordination of body and/or limb segments
•Postural control•Spatial-temporal coupling between limbs and limb
segments•Adapting to new situations requiring non-preferred
movement coordination patterns
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Vision and Motor ControlVision and Motor Control
Vision is our preferred source of sensory information
Evidence from everyday experiences•Beginning typists look at their fingers•Beginning dancers look at their feet
Evidence from research•The classic “moving room experiment”
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The Moving Room ExperimentThe Moving Room Experiment
Lee & Aronson (1974) Participants stood in a
room in which the walls moved toward or away from them but floor did not move
Situation created a conflict between which two sensory systems?
Vision & proprioception
Results When the walls
moved, people adjusted their posture to not fall, even though they weren’t moving off balance
WHY?
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Neurophysiology of VisionNeurophysiology of Vision
Basic Anatomy of the Eye See Figure 6.6 for the following
anatomical components•Cornea•Iris•Lens•Sclera•Aqueous humor•Vitreous humor
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Neurophysiology of Vision, cont’dNeurophysiology of Vision, cont’d
Neural Components of the Eye and Vision Retina [see Fig. 6.6]
•Fovea centralis•Optic disk•Rods•Cones
Optic nerve (cranial nerve II) [Fig. 6.7]•From the retina to the brain’s visual cortex
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Techniques for Invesigating the Role of Vision in Motor ControlTechniques for Invesigating the Role of Vision in Motor Control
Eye movment recording•Tracks foveal vision’s “point of gaze”
i.e. “what” the person is looking at
Temporal occlusion techniques•Stop video or film at various times•Spectacles with liquid crystal lenses
Event occlusion technique•Mask view on video or film of specific
events or characteristics
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Role of Vision in Motor ControlRole of Vision in Motor Control
Evidence comes from research investigating specific issues and vision characteristics:
1. Monocular vs. Binocular Vision Binocular vision important for depth-
perception when 3-dimensional features involved in performance situation, e.g.
•Reaching – grasping objects•Walking on a cluttered pathway•Intercepting a moving object
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Role of Vision in Motor Control, cont’d.Role of Vision in Motor Control, cont’d.
2. Central and Peripheral Vision Central vision
•Sometimes called foveal visionMiddle 2-5 deg. of visual field
•Provides specific information to allow us to achieve action goals, e.g.
For reaching and grasping an object – specific characteristic info, e.g. size, shape, required to prepare, move, and grasp object
For walking on a pathway – specific pathway info needed to stay on the pathway
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Role of Vision in Motor Control, cont’d.Role of Vision in Motor Control, cont’d.
2. Central and Peripheral Vision, cont’d. Peripheral vision
•Detects info beyond the central vision limitsUpper limit typically ~ 200 deg.
•Provides info about the environmental context and the moving limb(s)
•When we move through an environment, peripheral vision detects info by assessing optical flow patterns
Optical flow = rays of light that strike the retina
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Role of Vision in Motor Control, cont’d.Role of Vision in Motor Control, cont’d.
2. Central and Peripheral Vision, cont’d Two visual systems
•Vision for perception (central vision)Anatomically referred to as the ventral stream –
from visual cortex to temporal lobeFor fine analysis of a scene, e.g. form, featuresTypically available to consciousness
•Vision for action (peripheral vision)Anatomically referred to as the dorsal stream –
from visual cortex to posterior parietal lobe For detecting spatial characteristics of a scene and
guiding movementTypically not available to consciousness
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Role of Vision in Motor Control, cont’d.Role of Vision in Motor Control, cont’d.
3. Perception – Action Coupling As discussed in ch. 5, refers to the
“coupling” (i.e. linking together) of a perceptual event and an action
Example of research evidence:•See experiments by Helsen et al. (1998 &
2000) described in textbook (pp.127 – 128)•Results show that spatial and temporal
characteristics of limb movements occurred together with specific spatial and temporal characteristics of eye movements
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Role of Vision in Motor Control, cont’d.Role of Vision in Motor Control, cont’d.
4. Amount of Time Needed for Movement Corrections?
Concerns vision’s feedback role during movement Researchers have tried to answer this question
since original work by Woodworth in 1899 Typical procedure: Compare accuracy of rapid
manual aiming movements of various MTs with target visible and then not visible just after movement begins
•Expect accurate movement with lights off when no visual feedback needed during movement
•Currently, best estimate is a range of 100 – 160 msec. (The typical range for simple RT to a visual signal)
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Role of Vision in Motor Control, cont’d.Role of Vision in Motor Control, cont’d.
5. Time-to-Contact: The Optical Variable tau Concerns situations in which
•Object moving to person must be intercept•Person moving toward object needs to contact or
avoid contact with object Vision provides info about time-to-contact object which
motor control system uses to initiate movement•Automatic, non-conscious specification based on
changing size of object on retina•At critical size, requisite movement initiated
David Lee (1974) showed the time-to-contact info specified by an optical variable (tau), which could be mathematically quantified
Motor control benefit – Automatic movement initiation
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Chapter 6Chapter 6
Touch, Proprioception and Vision