Learning the Optimal Control of Coordinated Eye and Head Movements

Sohrab Saeb,Cornelius Weber,Jochen Triesch,Jörn Diedrichsen

doi:10.1371/journal.pcbi.1002253

Abstract

Various optimality principles have been proposed to explain the characteristics of coordinated eye and head movements during visual orienting behavior. At the same time, researchers have suggested several neural models to underly the generation of saccades, but these do not include online learning as a mechanism of optimization. Here, we suggest an open-loop neural controller with a local adaptation mechanism that minimizes a proposed cost function. Simulations show that the characteristics of coordinated eye and head movements generated by this model match the experimental data in many aspects, including the relationship between amplitude, duration and peak velocity in head-restrained and the relative contribution of eye and head to the total gaze shift in head-free conditions. Our model is a first step towards bringing together an optimality principle and an incremental local learning mechanism into a unified control scheme for coordinated eye and head movements.

Highlights

Active perception of the visual world necessitates frequent redirection of our gaze
Human beings and many other species redirect their gaze towards targets of interest through rapid gaze shifts known as saccades
Various researchers have hypothesized that these principles are implications of some optimality criteria in the brain, but it remains unclear how the brain can learn such an optimal behavior

Summary

Introduction

Active perception of the visual world necessitates frequent redirection of our gaze. Such visual orientation behavior comprises multi-segment control of different motor systems, i.e. the coordinated movement of several parts of the body including the eyes, the head, and the torso. In the head-restrained condition, head movement is limited so that the gaze shifts rely only on eye movements. These eye movements, known as eye-only saccades, possess certain physical properties. The relationship between the duration, peak velocity and the amplitude of saccades is known as the main sequence [1]. The velocity profiles of saccadic eye movements are smooth and symmetric for small amplitudes, while they become skewed for larger amplitudes [5,6]

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