The Neural Control of Visually Guided Eye Movements

A. The Classification of Eye Movements

The retina is specialized in having only a small region of tightly packed photoreceptors called the fovea. This region affords high-acuity vision. To be able to see fine detail in the visual scene, we therefore have to repeatedly shift the direction of our gaze.

Two general classes of eye movements have been distinguished: Conjugate eye movements and vergence eye movements. Conjugate eye movements are of two types: saccadic and smooth pursuit.

• The function of saccadic eye movements is to rapidly acquire objects in the visual scene for central viewing so that they may be analyzed in detail.

• The function of the smooth pursuit system is to maintain a moving object in central view as in the case of tracking a bird in flight.

For the most part different neural mechanisms control saccadic and smooth pursuit eye movements. Research in the Schiller Lab is concerned predominantly with the neural control of visually guided saccadic eye movements.