CHAPTER 4

Chapter Overview

  • Title: Vision, Hearing, and the Sensory Motor System

  • Copyright: © 2019, University of Cyberjaya

  • Notes are for educational purposes only.

Vision

The Perception Process

  • Visual Transformation: The 2-D retinal image is converted to a 3-D perception.

  • Research Types:

    • Components of the visual system

    • Assessment of visual perception

Light and Vision

  • Nature of Light:

    • Particles (photons) and waves (electromagnetic radiation)

    • Visible spectrum for humans: 380-760 nanometers

  • Wavelength: Determines color perception

  • Intensity: Affects brightness perception

The Eye's Anatomy

  • Pupil and Lens:

    • Pupil size adjusts to light levels

    • Sensitivity: Ability to see in dim light

    • Acuity: Ability to discern details

  • Accommodation: Lens shape is adjusted for focus

The Retina

  • Function: Translates light into neural signals

    • Structure: Light journey involves several cell layers

    • Transduction: Conversion of light into neurological signals

    • Blind Spot: Area with no receptors for completion of images

    • Fovea: High acuity center of retina

Color Vision

  • Cones and Color Detection:

    • Cone types sensitive to different wavelengths

    • Trichromatic Theory: Colors perceived by combining red, green, and blue light

Hearing

Auditory System Introduction

  • Complex Sounds: Composed of various sine wave patterns

  • Fourier Analysis: Breaks sounds into sine waves

Ear Anatomy

  1. Outer Ear: Directs sound waves

  2. Middle Ear: Contains ossicles (malleus, incus, stapes) which transmit vibrations

  3. Inner Ear: Includes cochlea for hearing, semicircular ducts for balance

Physiology of Hearing

  • Sound Processing Steps:

    1. Auricle captures sound waves.

    2. Waves vibrate the eardrum.

    3. Vibrations pass through ossicles.

    4. Oval window movement generates pressure waves in the cochlea.

    5. Fluid pressure activates hair cells, resulting in signal transmission to the brain.

Equilibrium

  • Function: Maintains body position in relation to gravity

  • Static and Dynamic Equilibrium: Manage body balance during different movements

Sensory System Principles

Organization of Sensory Systems

  • Levels:

    • Primary: Input from thalamic relay nuclei

    • Secondary: Input from primary sensory areas

    • Association: Combines inputs from different systems

  • Processing:

    • Parallel Processing: Simultaneous analysis

    • Hierarchical Organization: Increasing specificity at each level

Somatosensory System

Sensation Types

  • Exteroceptive System: External stimuli (touch, temperature, pain)

  • Proprioceptive System: Body position monitoring

  • Interoceptive System: Internal body condition awareness

Receptor Types

  • Cutaneous Receptors: Detect sensations like touch and temperature

    • Free nerve endings, Meissner corpuscles, Pacinian corpuscles, etc.

  • Pain Perception: Fast vs. slow pain types and conditions causing pain

Special Senses

Olfaction (Smell)

  • Receptors: Respond to inhaled chemicals; replace every month

Gustation (Taste)

  • Taste Buds: Respond to five primary tastes; neurotransmitter release triggered by tastants

Summary of Visual Pathway

  • Photoreceptors: Rods and cones in the retina convert light to electrical signals

  • Mechanoreceptors in Hearing: Functions of outer, middle, and inner ear involving sound processing

Conclusion

  • Development and Plasticity: The brain's capabilities are influenced by sensory input and experiences.