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Strabismic amblyopia affects decision processes preceding saccadic response

Perdziak M., Witkowska D., Gryncewicz W., Ober J.

Biocybernetics and Biomedical Engineering

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2018

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Vol. 38, no. 1

190--199

EN

Amblyopia is a developmental disorder of vision associated with abnormal visual stimula- tion during early childhood. It is known that amblyopia may affect not only spatial vision parameters but also oculomotor behavior. Several previous studies showed that increased saccadic reaction time (latency) may be present in amblyopic subjects. In our recent work, we have demonstrated that not only amblyopic but also a dominant eye may show increased saccadic latency in strabismic individuals. Since saccadic latency can be considered as a decision time, we have applied LATER (Linear Approach to Threshold with Ergodic Rate) decision model to find out how developmental impairment of visual input affects visual decision-making processes, as well as to verify whether amblyopia affects also the cortical ability to inhibit more primitive, early saccadic responses during our modified delayed saccade task. Ten subjects with strabismic amblyopia and twelve control subjects were examined. As we expected, strabismic amblyopes showed decreased rate of rise of the neural decision signal for all viewing conditions as compared to controls. In addition, the comparison between the strabismic and anisometropic groups revealed that the amblyopic eye in strabismic subjects showed decreased rate of rise of the decision signal as compared to amblyopic eye in anisometropic subjects. Although we speculated that amblyopia may reduce the ability of cortical control and favor more reflexive, early saccadic actions to occur, our findings did not confirm this hypothesis. This study provide further evidence that amblyopia is associated with cortical deficits which affect the cortical decision about saccade initiation.

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An attempt to speed-up the examination of saccadic reaction time

Witkowska D., Ober J.

Biocybernetics and Biomedical Engineering

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2012

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Vol. 32, no. 3

79-94

EN

One of possible ways to speed-up the prosaccadic latency examination is applying the target walk paradigm. The authors describe the physiological phenomena involved in carrying such paradigms, which may affect latency time and which should be balanced in this kind of task. Thirteen subjects were examined applying the newly designed target-walk paradigm and for comparison the standard prosaccade task. A significant reduction of the saccadic latency (p < 0.0l) was found on average by 21 ms, which probably resulted from an increased saccadic decision urgency forced by the new test design. Another reason can be different ways of capturing of the subject's attention achieved in this task.

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The influence of coffee on an eyeball movement

Walecki P., Lasoń W., Gorzelańczyk E. J., Roterman I.

Bio-Algorithms and Med-Systems

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2008

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Vol. 4, no. 8

69--72

EN

This paper presents a research of in fluences of coffee on dynamic parameters of eyeballs movements. In this study we made use of a head-mounted saccadometer which measures parameters related to eyeball movement (duration, latency, amplitude, peak velocity). 19 people, selected by age, took part in the study. Coffee-consuming group subjects were chosen at random for the experimental group and proper subjects were assigned to the control group without taking coffee. The results of the study were divided into two groups: the first related to saccade dynamics and the second related to reaction time (latency) and accuracy. The statistical significance has not been found in the saccadic duration, amplitude and peak velocity. A significant difference in latency was observed in the Coffee-consuming group, though an increase in the number of mistakes (errors of saccade accuracy) was not observed. In reverse, in the Coffee-consuming group was observed a decrease in the errors of saccade accuracy.