# Axonal delays and on-time control of eye movements

## Marseille INT Fest

 Problem statement: optimal motor control under axonal delays. The central nervous system has to contend with axonal delays, both at the sensory and the motor levels. For instance, in the human visuo-oculomotor system, it takes approximately $\tau_s=50~\ms$ for the retinal image to reach the visual areas implicated in motion detection, and a further $\tau_m=40~\ms$ to reach the oculomotor muscles. As a consequence, for a tennis player trying to intercept a ball at a speed of $20~\m\cdot \s^{-1}$, the sensed physical position is $1~\m$ behind the true position (as represented here by $\tau_s \cdot \vec{V}$), while the position at the moment of emitting the motor command will be $.8~\m$ ahead of its execution ($\tau_m \cdot \vec{V}$). Note that while the actual position of the ball when its image hits photoreceptors on the retina is approximately at $45$ degrees of eccentricity (red dotted line), the player's gaze is directed to the ball at its \emph{present} position (red line), in anticipatory fashion. Optimal control directs action (future motion of the eye) to the expected position (red dashed line) of the ball in the future --- and the racket (black dashed line) to the expected position of the ball when motor commands reach the periphery (muscles).
Time
January 10th, 2014, 11:30am
Location
CAV/LPP - 45 rue des Saints PĂ¨res - salle H432

## reference

• Laurent U. Perrinet. Axonal delays and on-time control of eye movements, URL . In Marseille INT Fest, January 10th, 2014, 2014 abstract.

 This work was supported by European Union project Number FP7-269921, "BrainScales".

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