Basic principles of generating horizontal saccades

Saccades are one of 5 types of eye movements. They are used to point your fovea quickly from one object of interest to another, such as the words of this sentence.

The command for a saccade begins in a structure called the Paramadian Pontine Reticular Formation; the PPRF

  1. Burst neurons in the PPRF generate phasic movement command which is proportional to velocity
  2. Tonic neurons in prepositus hypoglossi (PPH)
    • converts the phasic command to a tonic command
    • this is like an integrator which converts velocity to position
  3. Motorneurons (MN's) combine phasic and tonic commands
    • this contracts muscles
    • quickly rotates the eyes (phasic component)
    • & then holds (tonic component) them there against the elastic restoring forces.

Copywrite © 1996 Tutis Vilis and Douglas Tweed
Department of Physiology
University of Western Ontario
London Ontario Canada
Updated October 04, 1996

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