Eye movements during vergence effort in stereoscopic ocular pursuit task and their relations to visual fatigue and stereopsis

Contribution of the cerebellar flocculus to gaze control during active head movements. The flocculus and ventral paraflocculus are adjacent regions of the cerebellar cortex that are essential for controlling smooth pursuit eye movements and for altering the performance of the vestibulo-ocular reflex (VOR). The question addressed in this study is whether these regions of the cerebellum are more globally involved in controlling gaze, regardless of whether eye or active head movements are used to pursue moving visual targets. Single-unit recordings were obtained from Purkinje (Pk) cells in the floccular region of squirrel monkeys that were trained to fixate and pursue small visual targets. Cell firing rate was recorded during smooth pursuit eye movements, cancellation of the VOR, combined eye-head pursuit, and spontaneous gaze shifts in the absence of targets. Pk cells were found to be much less sensitive to gaze velocity during combined eye–head pursuit than during ocular pursuit. They were not sensitive to gaze or head velocity during gaze saccades. Temporary inactivation of the floccular region by muscimol injection compromised ocular pursuit but had little effect on the ability of monkeys to pursue visual targets with head movements or to cancel the VOR during active head movements. Thus the signals produced by Pk cells in the floccular region are necessary for controlling smooth pursuit eye movements but not for coordinating gaze during active head movements. The results imply that individual functional modules in the cerebellar cortex are less involved in the global organization and coordination of movements than with parametric control of movements produced by a specific part of the body.

Download Full-text

Visual Fatigue and Saccadic Eye Movement Parameters

Proceedings of the Human Factors Society Annual Meeting ◽

10.1177/154193128302700818 ◽

1983 ◽

Vol 27 (8) ◽

pp. 728-732 ◽

Cited By ~ 4

Author(s):

Ted Megaw ◽

Tayyar Sen

Keyword(s):

Eye Movements ◽

Eye Movement ◽

Peak Velocity ◽

Cognitive Task ◽

Saccadic Eye Movements ◽

Tracking Task ◽

Frequency Of Occurrence ◽

Saccadic Eye Movement ◽

Visual Fatigue ◽

Movement Parameters

It has been suggested by Bahill and Stark (1975) that visual fatigue can be identified by changes in some of the saccadic eye movement parameters. These include increases in the frequency of occurrence of glissades and overlapping saccades and reductions in the peak velocity and duration of saccades. In their study, fatigue was induced by the same step tracking task that was used to evaluate the changes in saccadic parameters. However, there is evidence that subjects experience extreme feelings of fatigue while performing such a task and that somehow the task is unnatural. The present study was designed to assess whether there are any differences in the various saccadic parameters obtained while subjects perform a step tracking task and a cognitive task involving the comparison of number strings. Both tasks were presented on a VDU screen. The second objective was to establish whether there are any changes in the parameters for either task as a result of prolonged performance. The results showed no major differences in the saccadic eye movements between the two tasks and no consistent changes resulting from prolonged performance.

Download Full-text

Microsaccadic eye movements during ocular pursuit

Journal of Vision ◽

10.1167/5.8.697 ◽

2010 ◽

Vol 5 (8) ◽

pp. 697-697

Author(s):

L. Jie ◽

J. J. Clark

Keyword(s):

Eye Movements ◽

Ocular Pursuit

Download Full-text

THE IMPROVEMENT OF PROFESSIONAL TRAINING ORGANIZATION OF THE X-RAY SCREENING SYSTEMS OPERATORS BY USING THE EYE MOVEMENTS REGISTRATION SYSTEM AND METHODS OF CLUSTER AND DISCRIMINANT ANALYSIS

Civil Aviation High TECHNOLOGIES ◽

10.26467/2079-0619-2018-21-3-45-36 ◽

2018 ◽

Vol 21 (3) ◽

pp. 45-36

Author(s):

A. K. Volkov ◽

V. V. Ionov

Keyword(s):

Visual Search ◽

Eye Movements ◽

Eye Tracking ◽

Eye Movement ◽

Professional Training ◽

Visual Fatigue ◽

Registration System ◽

X Ray ◽

Tracking Technology ◽

Screening Systems

The X-ray screening systems operators’ professional training is based on the CBT (computer-based training) principle, which has algorithms of adaptive training. These algorithms in existing computer simulators include feedback mechanisms on the basis of trainability exponents – such as the frequency of detecting dangerous objects, the frequency of false alarms and detection time. Further enhancement of the operators’ simulator training effectiveness is associated with the integration of psychophysiological mechanisms providing monitoring of their functional state. Based on the analysis of the particularities of x-ray screening systems operators’ professional training associated with the formation of competences in dangerous objects visual search, the most perspective method is the Eye tracking technology. Domestic and foreign studies of the eye movements characteristics while solving professional tasks in training process are actively developed in various areas. There are no studies of visual search peculiarities in domestic practice in contrast to exterior studies. This research is aimed at considering the usage of Eye tracking technology in the training of x-ray screening systems operators. As the result of the experimental research with the use of mobile eye-tracker Sensomotoric Instruments Eye Tracking Glasses 2.0 the statistical data of eye movement parameters of two groups of subjects with different levels of training have been received. The application of cluster and discriminant analyses methods allowed to identify General classes of these parameters, as well as to obtain the discriminants functions for each group under examination. The theoretical significance of the peculiarities of the operators’ eye movement studies is to identify the patterns of prohibited items visual search. The practical importance of implementation of Eye tracking technology and statistical analysis methods is to increase the reliability of assessment the level of formed competence of x-ray screening systems’ operators in visual search, as well as to develop the potential system of operators’ state monitoring and assessing their visual fatigue.

Download Full-text

The Influence of Briefly Presented Randomized Target Motion on the Extraretinal Component of Ocular Pursuit

Journal of Neurophysiology ◽

10.1152/jn.01033.2007 ◽

2008 ◽

Vol 99 (2) ◽

pp. 831-842 ◽

Cited By ~ 20

Author(s):

G. R. Barnes ◽

C. J. S. Collins

Keyword(s):

Eye Movements ◽

Intertrial Interval ◽

Peak Velocity ◽

Target Motion ◽

Target Velocity ◽

Initial Exposure ◽

Ocular Pursuit ◽

Dependent Component ◽

Velocity Information ◽

Eye Velocity

We assessed the ability to extract velocity information from brief exposure of a moving target and sought evidence that this information could be used to modulate the extraretinal component of ocular pursuit. A step-ramp target motion was initially visible for a brief randomized period of 50, 100, 150, or 200 ms, but then extinguished for a randomized period of 400 or 600 ms before reappearing and continuing along its trajectory. Target speed (5–20°/s), direction (left/right), and intertrial interval (2.7–3.7 s) were also randomized. Smooth eye movements were initiated after about 130 ms and comprised an initial visually dependent component, which reached a peak velocity that increased with target velocity and initial exposure duration, followed by a sustained secondary component that actually increased throughout extinction for 50- and 100-ms initial exposures. End-extinction eye velocity, reflecting extraretinal drive, increased with initial exposure from 50 to 100 ms but remained similar for longer exposures; it was significantly scaled to target velocity for 150- and 200-ms exposures. The results suggest that extraretinal drive is based on a sample of target velocity, mostly acquired during the first 150 ms, that is stored and forms a goal for generating appropriately scaled eye movements during absence of visual input. End-extinction eye velocity was significantly higher when target reappearance was expected than when it was not, confirming the importance of expectation in generating sustained smooth movement. However, end-extinction eye displacement remained similar irrespective of expectation, suggesting that the ability to use sampled velocity information to predict future target displacement operates independently of the control of smooth eye movement.

Download Full-text