In the pulse-step model of ocular motility, which component is primarily responsible for the speed of the eye movement?

• A. Step
• B. Both
• C. None
• D. Pulse

Answer: (D)

The speed of the eye movement in the pulse-step model comes from the pulse. This component provides a brief, high-frequency burst of neural drive that rapidly activates the extraocular muscles, producing a fast, high-velocity saccade. The speed and peak velocity depend on the pulse’s amplitude and duration, shaping how quickly the eye accelerates and reaches its target.

The step, on the other hand, is a tonic signal that holds the eye in the new position after the pulse has finished. It maintains fixation but does not drive the rapid movement itself, so it doesn’t determine how fast the eye moves. In short, the pulse governs speed, while the step governs final position.