Eye Movements

Last edited October 23, 2002
If the sence of sight be wonderfull, the member or instrument serving for the same can not but goe beyond all wonder; for it is framed so cunningly, and of such beautifull parts, as that there cannot be the man which is not ravished with the consideration of the same...

The muscles were of necessitie provided and given to the eye, that so it might move on every side; for if the eye stoode faste and immoveable, we should be constrained to turne our head and necke (being all of one peece) for to see; but by these muscles it now moveth it selfe with such swiftness and nimbleness, without stirring of the head as is almost incredible...

A. Du Laurens (1599) A Discourse of the Preservation of Sight: of Melancholike Diseases; of Rheumes, and of Old Age

  1. Introduction
    1. Visual basis for eye movements
      1. The primate eye
      2. Need to look to see...
        1. Need for accurate visually guided movements
        2. Stablized images disappear
        3. Active, self-generated movement necessary for adaptation and development
        4. Retinal topography
          1. Rabbit
          2. Carnivore
          3. Primate
      3. but cannot see when you look.
        1. Saccadic suppression
    2. Types of eye movements
      1. Gaze holding
      2. Gaze shifting
    3. History
      1. A. Du Laurens, 1599, one of the earliest detailed descriptions of the anatomy of the eye and associated musculature as well as theories of vision.
      2. F.C. Donders
        1. 1846, observed that for each direction of gaze the eyes assume the same position. Helmholtz (1866) called this Donder's law.
        2. 1862, earliest reliable measurements of the center of rotation of the eye
        3. 1868, conceived of using reaction times to measure speed of mental operations using subtraction method
      3. J.B. Listing
        1. observed that when the eye moves to any position from the primary position, it rotates about an axis that is perpendicular to the initial and final directions of gaze at the point of their intersection. Listing's law formulated and named by C.G.T. Reute in 1853
      4. E. Hering
        1. Hering's law - during conjugate eye movements each eye receives equal innervation
        2. Relation of eye movements and attention


          3. The movements from one point of fixation to another are occasioned and regulated by the changes of place of the attention. When an object, seen at first indirectly, draws our attention to itself, the corresponding movement of the eye follows without further ado, as a consequence of the attention's migration and of our effort to make the object distinct. The wandering of the attention entails that of the fixation point. Before its movement begins, its goal is already in consciousness and grasped by the attention, and the location of this spot in the total space seen is what determines the direction and amount of the movement of the eye. (1880) in Hermann's Handbuch der Physiologie
           

      5. E. Landolt
        1. 1891, coined term 'saccade' to describe rapid eye movements made during reading
      6. R. Dodge
        1. 1902, First identification of different types of eye movements
      7. 1920s
        1. first recordings of electrooculogram
      8. 1950s
        1. Accurate recording techniques
          1. measure angle of light reflected off of mirror attached to the eye, e.g., with contact lens
        2. Examined question of vision during stablized image
        3. Beginning analysis using ideas from feedback control systems
      9. 1960s
        1. New recording techniques
          1. relative reflection of light from limbus, Rashbass; Stark & Young
          2. video image of eye, Mackworth
          3. invention of scleral search coil, Robinson
        2. Improved data on mechanics of saccadic and pursuit eye movements
      10. 1970s
        1. Physiology in alert, behaving monkeys
        2. Development of concrete models of saccade generation
      11. 1980s
        1. Clarification of the involvement of more structures in gaze control, in particular cortical areas, thalamus and basal ganglia
      12. 1990s
        1. Begin work on problems of target selection and fixation duration, attention
  2. Neural basis of saccadic eye movements
    1. Overview
    2. Extraocular muscles
      1. Six of them
      2. Pulse & step of force
    3. Brainstem
      1. Motor neurons
      2. Burst cells
        1. Eye velocity
        2. Dynamic motor error
      3. Tonic cells
        1. Eye position
        2. Neural integrator
      4. Pause cells
        1. Gate
      5. Circuitry
      6. The brainstem saccade generator is controlled by a network of structures in the forebrain
    4. Superior colliculus
      1. Visual neurons
        1. Receptive field
        2. Visual field map
        3. Enhancement
      1. Movement neurons
        1. Movement field
        2. Electrical stimulation
        3. Saccade map
    5. Basal ganglia
      1. Caudate nucleus
      2. Substantia nigra
        1. Inhibition of the superior colliculus
    6. Cerebral cortex
      1. The problem of saccade target selection
        1. Schall JD. The neural selection and control of saccades by the frontal eye field. Philos Trans R

          2. Soc Lond B Biol Sci. 2002 Aug 29;357(1424):1073-82.
        2. Many things to look at, but you can only look at one at a time
        3. The eyes must move to see, but vision is impaired during saccades, so a judicious balance must be achieved.
      2. Frontal eye field
        1. Visual responses
          1. Enhancement
          2. Target selection
        2. Stimulation map
        3. Movement cells
          1. Project to SC and brainstem
          2. Relation of activity to saccade initiation
            1. Countermanding paradigm
      3. Supplementary eye field
        1. Monitoring the consequences of behavior
          1. Detecting errors
          2. Detecting success
          3. Schall J, Stuphorn V, Brown J. Monitoring and control of action by the frontal lobes. Neuron.

            4. 2002 Oct 10;36(2):309.