2007 Sensory Physiology

Acuity: the ability to precisely localize a stimulus

• acuity is determined by two factors:

1. RECEPTIVE FIELD SIZE: the smaller the receptive field, the better the acuity S&G Figure 10.11 (see also the discussion of 2 point discrimination)
2. RECEPTOR DENSITY: the more receptors per receptive field, the better the acuity generally, receptors are concentrated in the centre of the receptive field

• the fact that both stimulus intensity and location are encoded by the number of action potentials in the afferent pathway creates a PARADOX: the more intense the stimulus, the less precisely a stimulus can be localized
• the CNS resolves this paradox through the process called LATERAL INHIBITION

• Information Processing
• Transduction
  • Receptor potential
  • Receptor types
  • Sensory unit
  • Stimulus coding
    • Modality
      • Specificity
      • Coding theories
    • Intensity
      • Coding mechanisms
    • Duration
      • Adaptation
    • Location
      • Lateral inhibition
• Transmission
  • Generic sensory pathway
  • Complex processing
• Perception
  • Awareness