2014 Sensory Physiology

Critical Facts IconStimulus Intensity

Coding mechanisms

 

1. FREQUENCY CODING :

  • increase the firing rate of individual primary afferent fibres by increasing the size of the receptor potential

  • most common way to do this is by increasing the size of the receptive field stimulated

Graded potential (reprise)

Sensory unit (reprise)

Population coding2. POPULATION CODING :

  • increase the number of primary afferent fibres responding

  • this process is called RECRUITMENT

  • recruited fibres will not respond equally
    • because of frequency coding, the primary afferent whose receptive field is in the centre of the point of stimulation (i.e. the green fibre) will respond with the largest number of action potentials
    • this concept is critical with respect to understanding lateral inhibition
Email: Dr. Janet Fitzakerley | ©2014 University of Minnesota Medical School Duluth | Last modified: 4-feb-14 8:26 PM