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Biomedical subjects

T Elsner

Publications and source records attributed to T Elsner.

4 recordsLinked to original sources

Saccadic eye movements and the detection of fast-moving gratings.

Experiments are presented in which the effect of saccadic eye movements on the visibility of sinusoidal gratings drifting with velocities between 2 deg/s and 400 deg/s is investigated. The results demonstrate that saccades are highly useful for detecting this class of stimuli. Due to a saccade, otherwise subthreshold stimuli become visible as short, distinct flashes of the seemingly stationary pattern. The paper analyzes in detail the dependence of the amount of facilitation on saccade size and relative direction and isolates the additional effect of saccadic suppression. A simple model is proposed which predicts the experimental findings.

Eye Movements

A primary genetic linkage map for human chromosome 12.

A primary genetic map for human chromosome 12 has been constructed from data on 23 restriction fragment length polymorphic systems collected in 38 normal families with large sibships. Linkage analysis of the genotypic data has ordered 16 loci into a continuous genetic map of 111 cM in males and 258 cM in females. Although most of the genetic map reflects a higher rate of recombination in females relative to males, significantly more frequent recombination was observed in males than in females in intervals between loci on the distal portion of the short arm of the chromosome. The mapping data shown here will serve as a first step toward a high-resolution genetic map for human chromosome 12.

Animals

Threshold perception and saccadic eye movements.

Involuntary eye movements were recorded during threshold detection tasks under various experimental conditions. The data were analyzed for interdependencies between stimulus parameters, detection performance, and oculomotor behaviour. The data demonstrate that under certain conditions, saccadic parameters are adaptive to specific stimulus properties. Further, the data suggest that for stationary patterns with low spatial frequencies and for gratings flickering with high temporal frequencies, detection is facilitated considerably by the occurrence of a saccadic eye movement. These facilitation effects are consistent with the predictions of a theoretical model presented in a previous paper.

Eye Movements

The effect of saccades on threshold perception--a model study.

The effect of saccadic eye movements on threshold perception is investigated theoretically. The proposed model considers eye movements by taking into account the shifting of the stimulus pattern on the retina during the occurrence of an eye movement. Saccades are characterized by high velocity and short duration. These motions cause overshoots in the response of linear filters to certain stimulus patterns. Therefore, the model predicts facilitation effects of saccades in the perception of low spatial frequency patterns and patterns flickering with high temporal frequencies. These results agree with experimentally obtained data presented in a subsequent paper. A simple approach is formulated which approximates the complex shifting function of a saccade by a switching of the pattern.

Eye Movements