Motor Control (MC 2) Past Paper (PDF)

EXSS3062 Motor Control & Learning Motor Control (MC 2) Acquiring Information: Sensory Proprioception Proprioception: A key role in coordinating, guiding/adjusting movement, & producing skilled performance. “The experience of our world, our reality, comes from...

EXSS3062 Motor Control & Learning Motor Control (MC 2) Acquiring Information: Sensory Proprioception Proprioception: A key role in coordinating, guiding/adjusting movement, & producing skilled performance. “The experience of our world, our reality, comes from sensation!” Prof. Stephen Cobley Faculty of Medicine & Health Sciences The University of Sydney Page 1  We acknowledge the tradition of custodianship and law of the Country on which the University of Sydney campuses stand. We pay our respects to those who have cared and continue to care for Country. Artist credit: Yanhambabirra Burambabirra Yalbailinya (Come, Share and Learn) 2020 by Luke Penrith The University of Sydney  COMMONWEALTH OF AUSTRALIA Copyright Regulations 1969 WARNING This material has been reproduced and communicated to you by or on behalf of the University of Sydney pursuant to Part VB of the Copyright Act 1968 (the Act). The material in this communication may be subject to copyright under the Act. Any further copying or communication of this material by you may be the subject of copyright protection under the Act. Do not remove this notice Assessment 1 - Lecture Quiz (Week 2) - Week 2 lecture quiz (on Canvas) available at 10 am post-lecture session. - Closes at 8 am pre-lecture of Week 3 (i.e., one week to complete). - 3 Motor Control & 3 Motor Learning MCQs. - MCQs are aligned to Learning Outcomes within respective lectures. - Two attempts per quiz, with highest score recorded. - Correct answers will become visible after the quiz has closed. 5% mark = Weighted average across quizzes ( X / 30 points possible, 6 per quiz). The University of Sydney Page 4 Motor Control (MC 2) Unit Learning Outcome LO 1 Explain the structure & function of sensory receptors as they relate to the control of voluntary & involuntary movement Lecture Learning Outcomes 1) Understand movement control is dependent on sensory afferent information. (& then integration with efferent neural activity). 2) Identify sensory sources of afferent information associated with movement. (i.e., receptors; information transduced to neural signalling; sensory information perceived). 2a) Understand how Cutaneous receptors (sense of touch) operate to inform motor control. 2b) Understand how Muscle spindles (muscle positioning – proprioception) operate to inform motor control. MC 2 Sensory Input: Sensory proprioception Recommended reading Magill, R. & Anderson, D. (2020). Motor Learning & Control: Concepts & applications (12th Ed). New York: McGraw-Hill. - particular sections in Chapter 6. Magill, R. & Anderson, D. (2016). Motor Learning & Control: Concepts & applications (11th Ed). New York: McGraw-Hill. - particular sections in Chapter 6. See Canvas Reading List 1) Motor Control - Voluntary movement - Efferent & Afferent (sensory) neural activity is critical. Kolb & Whishaw (2012)  1) Motor Control – Afferent (sensory) systems Central Nervous System Efference Copy Perception, Cognition, Decision-making, Movement Neural commands planning Afferent (sensory) systems Efferent Motor System Proprioception (muscle spindles; GTO’s; joint receptors) Cutaneous receptors Vision Vestibular apparatus Biomechanical constraints of movement Muscular movement stimulation 1) Sensory (Afferent) Information How do we know sensory (afferent) receptors are important in movement control? A case to answer the question: The man who lost his body (i.e., sensory input) https://www.dailymotion.com/video/x12647t Full documentary available in sections on You Tube! Showcases what happens when you lose your sense of proprioception - Sensory (afferent nerve) information. 1) Sensory (Afferent) Information Importance of Proprioception in Motor Control. 1) Sensory (Afferent) Information Sensory poly-neuropathy = Degeneration of large afferent fibres carrying proprioceptive & tactile inputs (i.e., receptors in muscles [spindles, Golgi tendon organs, joint] & tactile/cutaneous receptors). Afferent neural information returning to the CNS is inhibited. Efferent motor pathways are intact - strength is normal. Pain & temperature sensation preserved. No stretch-reflex (e.g., knee jerk) Unable to: - grasp a pen & write - fasten buttons - hold a cup in one hand - unable to detect errors in movement - In rare cases where individuals re-learn, all movements have to be pre-planned & prepared (no sensory feedback or use visual feedback to guide movement) 1) Sensory (Afferent) Information Observations of sensory poly-neuropathy Rothwell (1982) Normative individual Sensory neuropathy patient. - Movement sequence with eyes closed. - Movement sequence with eyes closed. - Initial accuracy through movement - Movement error as task is continued or planning & sensory feedback preserved. repeated over time. “Can move the fingers but can’t feel it!” 1) Sensory (Afferent) Information Sensory poly-neuropathy: Tells us that sensory system (proprioception) is vital for movement control. In deafferented patients, CNS cannot construct accurate internal understanding of what is happening to limbs & body position during movement. Hence, starting points & changes in movement are unknown (i.e., not consciously aware of change). Sensory systems help generate internal representations (models) of the body & outside world. Condition invokes reliance on intact senses (i.e., vision) (e.g., watch feet when walking). Substantial training (years) needed to re-gain bodily control via alternate senses. 2) Identify sensory sources Core Facts: Sensory (afferent) system The sensory system has 5 common properties when stimulated: (i) Modalities (vision, touch etc) & their receptors. (ii) Location (where it is on/in body) (iii) Intensity (how many/much?) (iv) Timing (when & how long?) (v) Transduction (i.e., conversion of a signal to neural signalling for CNS) Together, the 5 properties link a stimulus with the yielding of sensation. All sensory systems convey similar types of neural information & may account for why they all have similar organization.  2a) Sensory System - Proprioception - Touch Modality Micro- neurography monitoring Fast Adapting Slow Adapting Fast Adapting Slow Adapting Type 1 Type 1 Type 2 Type 2 2a) Sensory System - Proprioception - Touch Modality 2a) Sensory System - Proprioception - Touch Modality (ii) Touch - Location Sensitivity in precise locations is important in many situations where actions are guided by spatial information (fingers, toes, mouth). Spatial distribution & density of cutaneous receptors conveys specific information about location of a stimulus on the body. Density of receptors determines how well sensory system can resolve the detail of stimuli. Two-point discrimination testing can determine how sensitive - densely populated - receptors are across the body. 2a) Sensory System - Proprioception - Touch Modality (ii & iii) Location & Intensity (Sensitivity) Two-Point Discrimination test Different distance points for different sections of the body. Distance until 2-point detection lost. 2a) Sensory System - Proprioception - Touch Modality (iii, iv, v) Intensity, Timing & Transduction Are quantitative relationships between sensory stimuli & psychological sensation. How physical stimuli correlate with psychological sensations = Psychophysics. Lawful relationship permits accuracy in perceptions of stimulus. You are interpreting info from your sensory nerves. Left chart = Degree of skin Right chart = Perceived indentation & afferent nerve firing intensity of sensation with rate. skin stimulus intensity  2a) Sensory System - Proprioception - Touch Modality (iii, iv, v) Intensity, Timing & Transduction Skin Indentation: Different receptors have different sensitivities Static Dynamic Pressure Change Meissner’s Merkel Cells Corpuscle Meissner’s & Merkel Cells + Pacinian Ruffini Endings Corpuscle Slow = mechanical static pressure Rapidly = mechanical fixed indentation dynamic indentation change. Different receptors stimulated at different points with different frequencies that provides info on when, degree, & change in skin indentation over time.  2a) Sensory System - Proprioception - Touch Modality How do we know the properties of different objects or surfaces? Identification via texture = rubbing surface of skin. Probe onto skin Sideways movement Fast-Adapting Type 1 Receptor Response (i.e., Meissner’s corpuscle) Differences in neural firing patterns lead to an association of different objects & surfaces. 2b) Sensory System - Proprioception - Muscle Receptors 2 Types - Muscle Spindles & Golgi Tendon Organs (i) Modality = Muscle Spindles https://www.youtube.com/watch?v=F0dp7A4IKyY 2b) Sensory System - Proprioception - Muscle receptors 2 Types - Muscle Spindles & Golgi Tendon Organs (i) Modality = Muscle Spindles Muscle spindles are responsive to stretch (lengthening & partial shortening) Detects: - Rate of change (speed) in muscle. - Absolute muscle fiber length Different modality but similar structural properties: (ii) Location (iii) Intensity (iv) Timing (v) Transduction Targeted at gathering similar sensory information Magill & Anderson (2014) 2b) Sensory System - Proprioception - Muscle Spindles (ii) Non-uniform distribution (Location) Significantly larger spindle numbers (3000+ est.) in muscles associated with head & neck movement. Significantly larger spindle numbers (4000+ est.) associated with muscles in trunk & hip movement. Large numbers of spindles in muscles spanning across joint areas (e.g., shoulder; 1300+ est. ) Lower number of spindles in smaller size muscle fibres of simpler movement forms (e.g., 3rd & 4th finger = 50-60 est.) Helps generate substantial sensory information about general & specific muscle positions. 2b) Sensory System - Proprioception - Muscle Spindles (iii & iv) Intensity & timing (sensitivity change) Static & dynamic activation of muscle (efferent nerves) sensitises static & dynamic muscle spindles. Muscle spindles also have adjustable sensitivity due to fusimotor drive (i.e., efferent nerves changing muscle fibre length). Means static or dynamic spindle sensitivity is adjusted according to the task performed & degree of need for movement control.  2b) Sensory System - Proprioception - Muscle Spindles (iii & iv) Intensity & timing (sensitivity change) Recordings of muscle spindle types in a cat according to movement type. Sensitivity of spindle type adjusted according to movement type No movement or fixed position = static. Imposed movement = dynamic Dangerous Movement = Both (highly sensitive) Sensitivity of muscles spindles according to task (rest - precarious) 2b) Sensory System - Proprioception - Muscle Spindles (iii & iv) Intensity & timing (sensitivity change). Example: Consider active muscles in a Single-Leg Hip Hinge (e.g., without vision) Sense awareness of position via active muscle spindles https://youtu.be/tX_0Pas9iNI?s i=FW2vxChjc2P4ZSlz Target muscle = Gluteus Maximus (red). Synergists = Hamstrings (dark-pink) Stabilizers = Abdom. muscles, Erector Spinae, Gluteus Medius. Transversus Abdominis. 2b) Sensory System - Proprioception - Muscle Spindles Muscle spindle function & activity. Alternative overview: https://www.youtube.com/watch?v=q-ImnmP-0Cg Motor Control (MC 2) Acquiring Information - Sensory (Afferent) Input: Sensory Proprioception Lecture Summary: Lecture content has explained how: Sensory afferent input is integral to movement control. Sensory (afferent) input continually occurs in different modalities & during movement. Cutaneous receptors - a form of proprioception (sense of touch) - provides preparatory &/or feedback related to body contact on external objects/surfaces, contributing to movement control. Muscles spindles - a form of proprioception (sense of muscular positioning) - provides continuous (& changeable) sensory feedback related to present muscle position. The rate of change in length and sustained positional information helps guide movement adjustment (i.e., control). Motor Control - Lecture Content in MC 2-4 Red highlights content covered in today’s lecture Sensory Receptor Organ Transduce (convert) Information Provided Eyes 3D light detector (adjustable) vision Ears sound detector hearing Vestibular System (utricle, multi-axial accelerometers balance, equilibrium saccule, semicircular canals) (linear & angular; adjustable) Cutaneous Receptors (Merkel cells, Ruffini endings, pressure, stretch, mechanical touch, pressure & texture Meissner's corpuscles, deformation, vibration Pacinian corpuscles) muscle length & velocity, joint Muscle Spindles length, velocity (adjustable) position & vibration Golgi Tendon Organs tension/force muscle tension (force) Joint Receptors mechanical deformation joint position & movement Efference Copy A copy of commands to reference information for Multiple locations within CNS muscles movement pain, itch, mechanical impacts Nociceptors mechanical impacts, vibrations & vibration MC 2 - Lecture Content Supplementary videos/material to assist learning: https://www.youtube.com/watch?v=X7xOEez75B0 https://www.dailymotion.com/video/x12647t https://www.youtube.com/watch?v=q-ImnmP-0Cg https://www.youtube.com/watch?v=F0dp7A4IKyY https://www.youtube.com/watch?v=wwQKSFKyD3U&t=221s