Chapter 6 Sensory Components of Motor Control Concept

Chapter 6 Sensory Components of Motor Control Concept: Touch, proprioception and vision are important components of motor control © 2011 Mc. Graw-Hill Higher Education. All rights reserved

Introduction n Sensory information is essential for all theories of motor control and learning • _________________ • Provides feedback about the movement in progress • ____________________________________ n Focus of current chapter is three types of sensory information • __________________ © 2011 Mc. Graw-Hill Higher Education. All rights reserved

Touch and Motor Control n Neural basis of touch [see Fig. 6. 1] • ___________ Mechanoreceptors located in the dermis layer of skin v________________________________ _ v © 2011 Mc. Graw-Hill Higher Education. All rights reserved

Touch and Motor Control, cont’d Roles of Tactile Info in Motor Control n Typical research technique n Research shows tactile sensory info influences: • Compare performance of task involving finger(s) before and after anesthetizing finger(s) • ______________________ See an example of research for typing – A Closer Look, p. 111 © 2011 Mc. Graw-Hill Higher Education. All rights reserved

_________________________________ n 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” © 2011 Mc. Graw-Hill Higher Education. All rights reserved

_________________ n _______ receives proprioception information from sensory neural pathways that begin in specialized sensory neurons known as proprioceptors • _______________________________________ n Three primary types of proprioceptors • ____________________________ • ______________ © 2011 Mc. Graw-Hill Higher Education. All rights reserved

Neural Basis of Proprioception: Proprioceptors 1. ______________ n In most skeletal muscles in a capsule of specialized muscle fibers and sensory neurons • _______________[see Fig. 6. 2] • ____________________ n Mechanoreceptors that detect changes in muscle fiber length (i. e. stretch) and velocity (i. e. speed of stretch) • ____________________ n Function - Feedback mechanism to CNS to maintain intended limb movement position, direction, and velocity © 2011 Mc. Graw-Hill Higher Education. All rights reserved

Neural Basis of Proprioception: Proprioceptors, cont’d 2. ________________ n In skeletal muscle near insertion of tendon n ________________ (i. e. force) • Poor detectors of muscle length changes 3. _________ n Several types located in joint capsule and ligaments n 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 © 2011 Mc. Graw-Hill Higher Education. All rights reserved

Techniques to Investigate the Role of Propioception in Motor Control 1. Deafferentation Techniques n _______________ • Afferent neutral pathways associated with movements of interest have been surgically removed or altered n Deafferentation due to sensory neuropathy • Sometimes called “___________” • _______________________________________ © 2011 Mc. Graw-Hill Higher Education. All rights reserved

Techniques to Investigate the Role of Propioception in Motor Control, cont’d 2. ______________ • ________________________________ • Proprioceptive feedback is distorted rather than removed © 2011 Mc. Graw-Hill Higher Education. All rights reserved

Role of Proprioceptive Feedback in Motor Control Research using deafferentation and tendon vibration techniques has shown that proprioception influences: n __________________ • Target accuracy • Spatial and temporal accuracy for movement in progress n _________________________________________ • Postural control • Spatial-temporal coupling between limbs and limb segments © 2011 Mc. Graw-Hill Higher Education. All rights reserved

Vision and Motor Control __________________ n Evidence from everyday experiences • Beginning typists look at their fingers • Beginning dancers look at their feet n Evidence from research • The classic “moving room experiment” © 2011 Mc. Graw-Hill Higher Education. All rights reserved

_________________ 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 Ø ________________ ________________ © 2011 Mc. Graw-Hill Higher Education. All rights reserved

Neurophysiology of Vision Basic Anatomy of the Eye n See Figure 6. 5 for the following anatomical components • • • ____________________ ____________________ © 2011 Mc. Graw-Hill Higher Education. All rights reserved

Neurophysiology of Vision, cont’d Neural Components of the Eye and Vision n _______ [see Fig. 6. 5] • • _______________ n _______(cranial nerve II) [Fig. 6. 6] • From the retina to the brain’s visual cortex © 2011 Mc. Graw-Hill Higher Education. All rights reserved

Techniques for Invesigating the Role of Vision in Motor Control n _______________ • Tracks foveal vision’s “point of gaze” v i. e. “what” the person is looking at n _______________ • Stop video or film at various times • Spectacles with liquid crystal lenses n ________________ • Mask view on video or film of specific events or characteristics © 2011 Mc. Graw-Hill Higher Education. All rights reserved

Role of Vision in Motor Control Evidence comes from research investigating specific issues and vision characteristics: 1. Monocular vs. Binocular Vision n __________________________________, e. g. • Reaching – grasping objects • Walking on a cluttered pathway • Intercepting a moving object © 2011 Mc. Graw-Hill Higher Education. All rights reserved

Role of Vision in Motor Control, cont’d. 2. ________________ n ____________ • Sometimes called foveal vision v Middle 2 -5 deg. of visual field • __________________, e. g. For reaching and grasping an object – specific characteristic info, e. g. size, shape, required to prepare, move, and grasp object v For walking on a pathway – specific pathway info needed to stay on the pathway v © 2011 Mc. Graw-Hill Higher Education. All rights reserved

Role of Vision in Motor Control, cont’d. 2. Central and Peripheral Vision, cont’d. n ______________ • Detects info beyond the central vision limits v Upper limit typically ~ 200 deg. • _____________________________________ • When we move through an environment, peripheral vision detects info by assessing optical flow patterns __________= rays of light that strike the retina v © 2011 Mc. Graw-Hill Higher Education. All rights reserved

Role of Vision in Motor Control, cont’d. 2. Central and Peripheral Vision, cont’d n Two visual systems • _____________(central vision) Anatomically referred to as the ventral stream – from visual cortex to temporal lobe v For fine analysis of a scene, e. g. form, features v Typically available to consciousness v • ____________(peripheral vision) Anatomically referred to as the dorsal stream – from visual cortex to posterior parietal lobe v For detecting spatial characteristics of a scene and guiding movement v Typically not available to consciousness v © 2011 Mc. Graw-Hill Higher Education. All rights reserved

Role of Vision in Motor Control, cont’d. 3. ________________ n As discussed in ch. 5, refers to the “coupling” (i. e. linking together) of a ________________ n Example of research evidence: • See experiments by Helsen et al. (1998 & 2000) described in textbook • Results show that spatial and temporal characteristics of limb movements occurred together with specific spatial and temporal characteristics of eye movements © 2011 Mc. Graw-Hill Higher Education. All rights reserved

Role of Vision in Motor Control, cont’d. 4. Amount of Time Needed for Vision-Based Movement Corrections? n _____________________ n Researchers have tried to answer this question since original work by Woodworth in 1899 n _________________________________________ • 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) © 2011 Mc. Graw-Hill Higher Education. All rights reserved

Role of Vision in Motor Control, cont’d. 5. __________: The Optical Variable tau n Concerns situations in which: • ____________________________________________ n Vision provides time-to-contact object info 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 n David Lee (1974) showed the time-to-contact info specified by a mathematically quantifiable optical variable, called tau n Motor control benefit – Automatic movement initiation © 2011 Mc. Graw-Hill Higher Education. All rights reserved