EXSS3062 Week 2 Lecture 1

Slide 1: Title Slide

• Course: EXSS3062 – Motor Control & Learning.

• Lecture Title: Motor Control (MC 2) – Acquiring Information: Sensory Proprioception.

• Key Theme: Understanding how sensory information, particularly proprioception, influences movement coordination and control.

Slide 2: Acknowledgment of Country

• A formal acknowledgment of the traditional custodians of the land where the University of Sydney is located.

• Artist Credit: Yanhambabirra Burambabirra Yalbailinya (Come, Share and Learn) (2020) by Luke Penrith.

Slide 3: Copyright Notice

• Standard warning about reproduction and communication of lecture materials under the Copyright Act 1968.

Slide 4: Assessment Details – Lecture Quiz (Week 2)

• Quiz Details:

• Available on Canvas after the lecture.

• Closes before the next lecture.

• 3 questions on Motor Control + 3 on Motor Learning.

• Aligned with lecture learning outcomes.

• Two attempts allowed; highest score recorded.

• Correct answers available after the quiz closes.

• Weighting: 5% of the total grade (out of 30 points).

Slide 5: Lecture Learning Outcomes

1. Understand how movement control depends on sensory afferent information and its integration with efferent neural activity.

2. Identify sources of sensory input related to movement (receptors, neural transmission, perception).

3. Explain cutaneous receptors and their role in motor control.

4. Explain muscle spindles and their role in proprioception.

• Unit Learning Outcome: Explain the structure and function of sensory receptors as they relate to voluntary and involuntary movement control.

Slide 6: Recommended Reading

• Textbook: Magill & Anderson (Motor Learning & Control: Concepts & Applications).

• Chapter 6: Relevant to sensory input and proprioception.

Slide 7: Motor Control – Afferent and Efferent Systems

• Motor control depends on:

• Afferent (sensory) information received by the CNS.

• Efferent motor commands sent to muscles.

• Sensory systems involved:

• Proprioception (muscle spindles, Golgi tendon organs, joint receptors).

• Cutaneous receptors (touch).

• Vision.

• Vestibular system.

• Efference copy (internal prediction of movement).

Slide 8: The Role of Sensory Information

• Question: How do we know sensory input is critical for movement control?

• Case Study: The Man Who Lost His Body (documentary link provided).

• Examines what happens when proprioception is lost.

• Highlights the importance of sensory afferent pathways (DCML – Dorsal Column Medial Lemniscus).

Slide 9: Importance of Proprioception in Motor Control

• Effects of losing proprioception:

• Large afferent fibers degenerate (muscle spindles, GTOs, joint receptors).

• Afferent signals to CNS are lost, but motor pathways remain intact.

• Symptoms:

• No stretch reflex.

• Cannot perform fine motor tasks (writing, buttoning a shirt).

• Needs visual guidance for movement.

Slide 10: Sensory Polyneuropathy – Observations

• Normal Individual:

• Can move accurately without visual feedback.

• Sensory Neuropathy Patient:

• “Can move the fingers but can’t feel it!”

• Relies heavily on vision to control movement.

• Takeaway: The CNS needs sensory feedback for movement accuracy.

Slide 11: Sensory System – Five Key Properties

1. Modality: Type of sensory information (touch, vision, etc.).

2. Location: Where the stimulus is detected.

3. Intensity: Strength of the stimulus.

4. Timing: When and how long the stimulus occurs.

5. Transduction: Conversion of stimulus into neural signals.

• All sensory systems process information similarly, allowing for multisensory integration.

Slide 12: Cutaneous Receptors (Touch) and Proprioception

• Function: Provide spatial information for movement.

• Density and Distribution:

• Fingers, lips, toes = high receptor density (greater sensory precision).

• Trunk, arms, legs = lower receptor density.

Slide 13: Two-Point Discrimination Test

• Measures touch sensitivity in different body parts.

• Smaller distance = greater receptor density = higher sensory resolution.

Slide 14: Psychophysics – Sensory Perception

• Relationship between physical stimuli and psychological perception.

• Example: Skin indentation leads to different neural firing rates.

• Interpretation: The brain deciphers intensity and texture based on afferent nerve signals.

Slide 15: Touch Receptors – Sensitivity to Indentation

• Slow-Adapting Receptors: Detect sustained pressure.

• Fast-Adapting Receptors: Detect dynamic changes.

Slide 16: Identifying Objects by Touch

• Mechanism: Different firing patterns of sensory neurons allow us to recognize textures.

• Example: Rubbing a surface with fingertips.

Slide 17: Proprioception – Muscle Spindles & GTOs

• Muscle Spindles: Detect length and speed of stretch.

• Golgi Tendon Organs (GTOs): Detect muscle tension.

• Video Link Provided: Explanation of muscle spindles.

Slide 18: Distribution of Muscle Spindles

• High spindle concentration: Neck, trunk, hips (for postural control).

• Lower concentration: Fingers, hands (for fine movement).

Slide 19: Spindle Sensitivity & Movement Control

• Adjustable sensitivity through efferent nerves.

• Changes based on task demand:

• Static sensitivity: Holds position.

• Dynamic sensitivity: Detects movement.

Slide 20: Sensory Feedback in a Single-Leg Hip Hinge

• Exercise Example: Sense position and movement using muscle spindles.

• Active muscles:

• Primary: Gluteus Maximus.

• Synergists: Hamstrings.

• Stabilizers: Core, Erector Spinae, Gluteus Medius.

Slide 21: Lecture Summary

• Key Points:

• Sensory input is essential for movement control.

• Cutaneous receptors provide touch and spatial feedback.

• Muscle spindles provide real-time muscle length and velocity feedback.

• Proprioception allows movement accuracy and correction.

Slide 22: Sensory Receptor Overview Table

• Takeaway: Sensory receptors contribute to movement accuracy and adaptation.

Slide 23: Additional Learning Resources

• Multiple YouTube & Dailymotion links for videos on proprioception, muscle spindles, and sensory control.