scholarly journals Velocity tuning of short-latency version and vergence eye movements in humans: dynamical limits set by retinal image speed

2010 ◽  
Vol 2 (7) ◽  
pp. 180-180
Author(s):  
F. A. Miles ◽  
G. S. Masson ◽  
D.-Y. Yang
Keyword(s):  
Eye Movements ◽  
Retinal Image ◽  
Short Latency

The effect of frontal eye field and superior colliculus lesions on saccadic latencies in the rhesus monkey

1987 ◽  
Vol 57 (4) ◽  
pp. 1033-1049 ◽  
Author(s):  
P. H. Schiller ◽  
J. H. Sandell ◽  
J. H. Maunsell
Keyword(s):  
Eye Movements ◽  
Superior Colliculus ◽  
Short Latency ◽  
The Other ◽  
Frontal Eye Field ◽  
Express Saccades ◽  
Unimodal Distribution ◽  
Other Hand ◽  
Eye Field ◽  
The Mean

Rhesus monkeys were trained to make saccadic eye movements to visual targets using detection and discrimination paradigms in which they were required to make a saccade either to a solitary stimulus (detection) or to that same stimulus when it appeared simultaneously with several other stimuli (discrimination). The detection paradigm yielded a bimodal distribution of saccadic latencies with the faster mode peaking around 100 ms (express saccades); the introduction of a pause between the termination of the fixation spot and the onset of the target (gap) increased the frequency of express saccades. The discrimination paradigm, on the other hand, yielded only a unimodal distribution of latencies even when a gap was introduced, and there was no evidence for short-latency "express" saccades. In three monkeys either the frontal eye field or the superior colliculus was ablated unilaterally. Frontal eye field ablation had no discernible long-term effects on the distribution of saccadic latencies in either the detection or discrimination tasks. After unilateral collicular ablation, on the other hand, express saccades obtained in the detection paradigm were eliminated for eye movements contralateral to the lesion, leaving only a unimodal distribution of latencies. This deficit persisted throughout testing, which in one monkey continued for 9 mo. Express saccades were not observed again for saccades contralateral to the lesion, and the mean latency of the contralateral saccades was longer than the mean latency of the second peak for the ipsiversive saccades. The latency distribution of saccades ipsiversive to the collicular lesion was unaffected except for a few days after surgery, during which time an increase in the proportion of express saccades was evident. Saccades obtained with the discrimination paradigm yielded a small but reliable increase in saccadic latencies following collicular lesions, without altering the shape of the distribution. Unilateral muscimol injections into the superior colliculus produced results similar to those obtained immediately after collicular lesions: saccades contralateral to the injection site were strongly inhibited and showed increased saccadic latencies. This was accompanied by a decrease of ipsilateral saccadic latencies and an increase in the number of saccades falling into the express range. The results suggest that the superior colliculus is essential for the generation of short-latency (express) saccades and that the frontal eye fields do not play a significant role in shaping the distribution of saccadic latencies in the paradigms used in this study.(ABSTRACT TRUNCATED AT 400 WORDS)

Dynamic Illusory Size Contrast

2017 ◽  
Author(s):  
Ryan E. B. Mruczek ◽  
D. Blair Christopher ◽  
Lars Strother ◽  
Gideon P. Caplovitz
Keyword(s):  
Eye Movements ◽  
Retinal Image ◽  
Target Motion ◽  
Moving Object ◽  
Size Change ◽  
Central Target ◽  
Powerful Effect ◽  
Size Contrast

Static size contrast and assimilation illusions, such as the Ebbinghaus and Delboeuf illusions, show that the size of nearby objects in a scene can influence the perceived size of a central target. This chapter describes a dynamic variant of these classic size illusions, called the Dynamic Illusory Size-Contrast (DISC) effect. In the DISC effect, a surrounding stimulus that continuously changes size causes an illusory size change in a central target. The effect is dramatically enhanced in the presence of additional stimulus dynamics arising from eye movements or target motion. The chapter proposes that this surprisingly powerful effect of motion on perceived size depends on the degree of uncertainty inherent in the size of the retinal image of a moving object.

Short-Latency Vergence Eye Movements Induced by Radial Optic Flow in Humans: Dependence on Ambient Vergence Level

1999 ◽  
Vol 81 (2) ◽  
pp. 945-949 ◽  
Author(s):  
D.-S. Yang ◽  
E. J. Fitzgibbon ◽  
F. A. Miles
Keyword(s):  
Eye Movements ◽  
Optic Flow ◽  
Radial Flow ◽  
Human Subjects ◽  
Short Latency ◽  
Viewing Distance ◽  
Focus Of Expansion ◽  
Random Dot Patterns

Yang, D.-S., E. J. Fitzgibbon, and F. A. Miles. Short-latency vergence eye movements induced by radial optic flow in humans: dependence on ambient vergence level. J. Neurophysiol. 81: 945–949, 1999. Radial patterns of optic flow, such as those experienced by moving observers who look in the direction of heading, evoke vergence eye movements at short latency. We have investigated the dependence of these responses on the ambient vergence level. Human subjects faced a large tangent screen onto which two identical random-dot patterns were back-projected. A system of crossed polarizers ensured that each eye saw only one of the patterns, with mirror galvanometers to control the horizontal positions of the images and hence the vergence angle between the two eyes. After converging the subject's eyes at one of several distances ranging from 16.7 cm to infinity, both patterns were replaced with new ones (using a system of shutters and two additional projectors) so as to simulate the radial flow associated with a sudden 4% change in viewing distance with the focus of expansion/contraction imaged in or very near both foveas. Radial-flow steps induced transient vergence at latencies of 80–100 ms, expansions causing increases in convergence and contractions the converse. Based on the change in vergence 90–140 ms after the onset of the steps, responses were proportional to the preexisting vergence angle (and hence would be expected to be inversely proportional to viewing distance under normal conditions). We suggest that this property assists the observer who wants to fixate ahead while passing through a visually cluttered area (e.g., a forest) and so wants to avoid making vergence responses to the optic flow created by the nearby objects in the periphery.

Adaptation to an altered relation between retinal image displacements and saccadic eye movements

1978 ◽  
Vol 18 (10) ◽  
pp. 1321-1327 ◽  
Author(s):  
Arien Mack ◽  
Robert Fendrich ◽  
Joan Pleune
Keyword(s):  
Eye Movements ◽  
Retinal Image ◽  
Saccadic Eye Movements

Visually induced adaptive changes in primate saccadic oculomotor control signals

1985 ◽  
Vol 54 (4) ◽  
pp. 940-958 ◽  
Author(s):  
L. M. Optican ◽  
F. A. Miles
Keyword(s):  
Eye Movements ◽  
Time Constant ◽  
Retinal Image ◽  
Prolonged Exposure ◽  
Oculomotor Control ◽  
Motor Deficits ◽  
Ocular Motor ◽  
Retinal Slip ◽  
Full Field ◽  
Adaptive Changes

Saccades are the rapid eye movements used to change visual fixation. Normal saccades end abruptly with very little postsaccadic ocular drift, but acute ocular motor deficits can cause the eyes to drift appreciably after a saccade. Previous studies in both patients and monkeys with peripheral ocular motor deficits have demonstrated that the brain can suppress such postsaccadic drifts. Ocular drift might be suppressed in response to visual and/or proprioceptive feedback of position and/or velocity errors. This study attempts to characterize the adaptive mechanism for suppression of postsaccadic drift. The responses of seven rhesus monkeys were studied to postsaccadic retinal slip induced by horizontal exponential movements of a full-field stimulus. After several hours of saccade-related retinal image slip, the eye movements of the monkeys developed a zero-latency, compensatory postsaccadic ocular drift. This ocular drift was still evident in the dark, although smaller (typically 15% of the amplitude of the antecedent saccade, up to a maximum drift of 8 degrees). Retinal slip alone, without a net displacement of the image, was sufficient to elicit these adaptive changes, and compensation for leftward and rightward saccades was independent. It took several days to complete adaptation, but recovery (in the light) was much quicker. The decay of this adaptation in darkness was very slow; after 3 days the ocular drift was reduced by less than 50%. The time constants of single exponential curve fits to adaptation time courses of data from five animals were 35 h for acquisition, 4 h for recovery, and at least 40 h for decay in darkness. Descriptions of the central innervation for a saccade are usually simplified to only two components: a pulse and a step. It has been hypothesized that suppression of pathological postsaccadic drift is achieved by adjusting the ratio of the pulse to the step of innervation (19, 26). However, we show that the time constant of the ocular drift is influenced by the time constant of the adapting stimulus, which cannot be explained by the simple pulse-step model of saccadic innervation. A more realistic representation of the saccadic innervation has three components: a pulse, an exponential slide, and a step. Normal saccades were accurately simulated by a fourth-order, linear model of the ocular motor plant driven by such a pulse-slide-step combination. Saccades made after prolonged exposure to optically induced retinal image slip could also be simulated by properly adjusting the slide and step components.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Short-latency disparity vergence eye movements: A response to disparity energy

2006 ◽  
Vol 46 (21) ◽  
pp. 3723-3740 ◽  
Author(s):  
B.M. Sheliga ◽  
E.J. FitzGibbon ◽  
F.A. Miles
Keyword(s):  
Eye Movements ◽  
Short Latency

Short-Latency Eye Movements: Evidence for Rapid, Parallel Processing of Optic Flow

2004 ◽  
pp. 79-107 ◽  
Author(s):  
F. A. Miles ◽  
C. Busettini ◽  
G. S. Masson ◽  
D. S. Yang
Keyword(s):  
Eye Movements ◽  
Parallel Processing ◽  
Optic Flow ◽  
Short Latency
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