CNS Sensory Physiology

Introduction

  • Overview of nervous system orientation and sensory physiology

Vision

  • Anatomy of the Eye
    • Components: Sclera, Ciliary body, Iris, Cornea, Retina, etc.
    • Photoreceptors: Rods (scotopic vision; sensitive to light) and Cones (photopic vision; color sensitivity)
  • Optics and Defects
    • Refraction: Bending of light rays.
    • Types of vision defects: Myopia (nearsightedness), Hyperopia (farsightedness), and Astigmatism.
  • From Light to Action Potentials
    • Phototransduction process: Light causes structural changes in retinal, which leads to neuron firing.
  • Optic Pathway
    • Path light takes to reach the visual cortex, including optic nerve, optic chiasm, and visual cortex.
  • Reflexes: Pupillary light reflex, accommodation reflex.

Hearing

  • Anatomy of the Ear
    • Outer, middle, and inner ear structures: Pinna, tympanic membrane, cochlea, etc.
  • Sound Transduction
    • Conversion of sound vibrations to neural signals via hair cells in the Organ of Corti.
  • Sonics and Localization
    • Determining sound direction via time and loudness differences between ears.
  • Hearing Thresholds and Acuity
    • Measured in decibels (dB); normal hearing range and auditory pathways.

Vestibular Function

  • Vestibular Apparatus
    • Components: Utricle, saccule, semicircular canals.
  • Functions
    • Equilibrium and balance through detection of head position and movement.

Taste and Smell

  • Gustation (Taste)
    • Structures like taste buds and types of papillae.
    • Mechanisms of taste sensation: Bitter, sour, sweet, salty, and umami.
  • Olfaction (Smell)
    • Olfactory receptors and pathways to perceptual brain areas.
    • Interaction with the limbic system influencing behavior.

Somatovisceral Sensation

  • Types of Sensory Receptors
    • Mechanoreceptors (touch, pressure), thermoreceptors (temperature), nociceptors (pain).
  • Sensory Pathways
    • Dorsal-columns and spinothalamic pathways for transmitting touch, pain, and temperature sensation.
  • Homunculus Representation
    • Organization of sensory cortex regarding body parts.

Pain

  • Definitions
    • Unpleasant sensory experience associated with tissue damage.
  • Classification of Pain
    • Acute vs. chronic, nociceptive vs. neuropathic pain.
  • Pain Transmission
    • A-delta and C fibers: Fast and slow pain pathways respectively.
  • Pain Treatment
    • Pharmacological (NSAIDs, opioids) and non-pharmacological methods (acupuncture, TENS).
  • Pain Inhibition
    • Role of endogenous opioids and effects on neurotransmitter release.

Additional Concepts

  • Receptive Fields
    • Area that excites a receptor; small receptor fields allow for finer discrimination of stimuli.
  • Sensory Adaptation
    • Phasic receptors adapt quickly to stimuli, while tonic receptors retain response over time.
  • Visual Defects and Corrections
    • Common defects and their optical corrections, e.g., lenses for myopia and hyperopia.
  • Normal Audiometry
    • Assessment of hearing ability; effects of age on auditory function.
  • Neural Pathways for Taste and Smell
    • Mechanoreceptors for taste; olfactory receptors involved in smell perception.