VisualEyes: A Modular Software System for Oculomotor Experimentation

Summary

Neural control and cognitive processes can be studied through eye movements. The VisualEyes software allows an operator to program stimuli on two computer screens independently using a simple, custom scripting language. The system can stimulate tandem eye movements (saccades and smooth pursuit) or opposing eye movements (vergence) or any combination.

Abstract

Eye movement studies have provided a strong foundation forming an understanding of how the brain acquires visual information in both the normal and dysfunctional brain.¹ However, development of a platform to stimulate and store eye movements can require substantial programming, time and costs. Many systems do not offer the flexibility to program numerous stimuli for a variety of experimental needs. However, the VisualEyes System has a flexible architecture, allowing the operator to choose any background and foreground stimulus, program one or two screens for tandem or opposing eye movements and stimulate the left and right eye independently. This system can significantly reduce the programming development time needed to conduct an oculomotor study. The VisualEyes System will be discussed in three parts: 1) the oculomotor recording device to acquire eye movement responses, 2) the VisualEyes software written in LabView, to generate an array of stimuli and store responses as text files and 3) offline data analysis. Eye movements can be recorded by several types of instrumentation such as: a limbus tracking system, a sclera search coil, or a video image system. Typical eye movement stimuli such as saccadic steps, vergent ramps and vergent steps with the corresponding responses will be shown. In this video report, we demonstrate the flexibility of a system to create numerous visual stimuli and record eye movements that can be utilized by basic scientists and clinicians to study healthy as well as clinical populations.

Protocol

An overview of the key elements needed to conduct an oculomotor experiment is shown in figure 1. Each block in the flow chart will be discussed in detail below.

1. INSTRUMENTATION SET-UP:

1. Any type of eye movement monitor can be used for this system. We will demonstrate an infrared limbus tracking and a video monitoring system.
2. For tandem tracking movements such as saccadic or smooth pursuit, a single computer can be used for the visual display. To study opposing eye movements such as vergence or the interaction of vergence with tandem version movements (ie, vergent with saccadic stimuli) a haploscope is needed wi....

Discussion

Critical Steps:

Eye movement monitors must be properly adjusted on the subject. For example, eye movement recording monitors work within a range and must be adjusted to the subject. If the subject's eye movement goes beyond the range, then the system becomes saturated. Upon saturation, the eye movement signal is not valid. Calibration is also critical in eye movement recording. All eye movement monitors measure an analog signal that is digitized and needs to be converted to units commonly used.......