Initiation of saccades during fixation or pursuit: evidence in humans for a single mechanism

1996 ◽  
Vol 76 (6) ◽  
pp. 4175-4179 ◽  
Author(s):  
R. J. Krauzlis ◽  
F. A. Miles
Keyword(s):  
Eye Movements ◽  
Human Subjects ◽  
Saccadic Eye Movements ◽  
Saccade Latency ◽  
Gap Effect ◽  
Time Interval ◽  
Single Mechanism ◽  
Eccentric Target

1. In four human subjects, we measured the latency of saccadic eye movements made to a second, eccentric target after an initial, foveated target was extinguished. In separate interleaved trails, the targets were either both stationary (“fixation”) or both moving with the same velocity (“pursuit”). For both fixation and pursuit trials, we extinguished the first target at randomized times during maintained fixation or pursuit and varied the time interval (“gap duration”) before the appearance of the second target. 2. During both fixation and pursuit, the presence of a 200-ms gap reduced the latencies of saccades, compared with those obtained with no gap. For two subjects, we imposed additional, intermediate gap durations and found that saccade latencies varied as a function of gap duration. Furthermore, the latencies of saccades elicited during pursuit displayed the same dependence on gap duration as those elicited during fixation. 3. Our results demonstrate that the “gap effect” observed for saccades made during fixation also occurs for saccades made during pursuit. To the extent that the gap effect on saccade latency reflects a mechanism underlying the release of fixation, our results suggest that the same mechanism is invoked for saccades made during pursuit. From the viewpoint of initiating saccades, the existence of separate fixation and pursuit systems may be irrelevant.

Release of fixation for pursuit and saccades in humans: evidence for shared inputs acting on different neural substrates

1996 ◽  
Vol 76 (5) ◽  
pp. 2822-2833 ◽  
Author(s):  
R. J. Krauzlis ◽  
F. A. Miles
Keyword(s):  
Spatial Organization ◽  
Human Subjects ◽  
Saccadic Eye Movements ◽  
Neural Substrates ◽  
Retinal Eccentricity ◽  
Time Interval ◽  
Central Target ◽  
Neural Substrate ◽  
Eccentric Target ◽  
Shared Inputs

1. In three human subjects, we measured the latency of pursuit and saccadic eye movements made to an eccentric target after a fixated central target was extinguished. In one set of experiments, we varied the time interval between the extinction of the central target and the appearance of the eccentric target (“gap duration”). In a second set of experiments, we varied the eccentricity at which the second target appeared. 2. Varying the gap duration produced similar changes in the latencies of pursuit and saccades. Gaps as short as 30 ms caused significant decreases in latency; progressively longer gaps produced shorter latencies, reaching a minimum for gaps of 150–200 ms. Over the range of gap durations used, the latencies of pursuit and saccades displayed the same dependence on gap duration. 3. Varying the eccentricity of the second target produced different effects on the latencies of pursuit and saccades. Saccade latencies increased when the eccentricity of the second target was decreased from 4 degrees to 0.5 degree, whereas pursuit latencies were not consistently altered. Despite these differences in the dependence on retinal eccentricity between pursuit and saccades, imposing a 200-ms gap between the extinction of the fixation point and appearance of the second target still reduced the latency of both. 4. Our results are consistent with the idea that the mechanisms underlying the release of fixation for pursuit and saccades have shared inputs but a different neural substrate. The common dependence on gap duration may indicate that a single preparatory input coordinates both types of movements. The different dependence on retinal eccentricity indicates that there are differences in the spatial organization of the premotor circuits that trigger the onset of the two types of movements.

scholarly journals The role of fixation disengagement in the parallel programming of sequences of saccades

2019 ◽  
Vol 237 (11) ◽  
pp. 3033-3045
Author(s):  
Eugene McSorley ◽  
Iain D. Gilchrist ◽  
Rachel McCloy
Keyword(s):  
Eye Movements ◽  
Parallel Programming ◽  
Response Times ◽  
Saccadic Eye Movements ◽  
Gap Effect ◽  
Task Completion ◽  
Published Data ◽  
Trial Duration ◽  
Visual Tasks

Abstract One of the core mechanisms involved in the control of saccade responses to selected target stimuli is the disengagement from the current fixation location, so that the next saccade can be executed. To carry out everyday visual tasks, we make multiple eye movements that can be programmed in parallel. However, the role of disengagement in the parallel programming of saccades has not been examined. It is well established that the need for disengagement slows down saccadic response time. This may be important in allowing the system to program accurate eye movements and have a role to play in the control of multiple eye movements but as yet this remains untested. Here, we report two experiments that seek to examine whether fixation disengagement reduces saccade latencies when the task completion demands multiple saccade responses. A saccade contingent paradigm was employed and participants were asked to execute saccadic eye movements to a series of seven targets while manipulating when these targets were shown. This both promotes fixation disengagement and controls the extent that parallel programming can occur. We found that trial duration decreased as more targets were made available prior to fixation: this was a result both of a reduction in the number of saccades being executed and in their saccade latencies. This supports the view that even when fixation disengagement is not required, parallel programming of multiple sequential saccadic eye movements is still present. By comparison with previous published data, we demonstrate a substantial speeded of response times in these condition (“a gap effect”) and that parallel programming is attenuated in these conditions.

Analysis of Saccadic Eye Movements Using an Infrared Video System in Human Subjects

1991 ◽  
Vol 111 (sup481) ◽  
pp. 382-387 ◽  
Author(s):  
Takeshi Kubo ◽  
Takanori Saika ◽  
Yoshiharu Sakata ◽  
Yasuhiro Morita ◽  
Toru Matsunaga ◽  
...  
Keyword(s):  
Eye Movements ◽  
Human Subjects ◽  
Saccadic Eye Movements ◽  
Video System ◽  
Infrared Video

scholarly journals The Limitations of Reward Effects on Saccade Latencies: An Exploration of Task-Specificity and Strength

Vision ◽  
2019 ◽  
Vol 3 (2) ◽  
pp. 20 ◽  
Author(s):  
Stephen Dunne ◽  
Amanda Ellison ◽  
Daniel T. Smith
Keyword(s):  
Eye Movements ◽  
Operant Conditioning ◽  
Saccadic Eye Movements ◽  
Oculomotor System ◽  
Saccade Latency ◽  
Visually Guided ◽  
Task Specificity ◽  
Specific Effects ◽  
Spatial Locations

Saccadic eye movements are simple, visually guided actions. Operant conditioning of specific saccade directions can reduce the latency of eye movements in the conditioned direction. However, it is not clear to what extent this learning transfers from the conditioned task to novel tasks. The purpose of this study was to investigate whether the effects of operant conditioning of prosaccades to specific spatial locations would transfer to more complex oculomotor behaviours, specifically, prosaccades made in the presence of a distractor (Experiment 1) and antisaccades (Experiment 2). In part 1 of each experiment, participants were rewarded for making a saccade to one hemifield. In both experiments, the reward produced a significant facilitation of saccadic latency for prosaccades directed to the rewarded hemifield. In part 2, rewards were withdrawn, and the participant made a prosaccade to targets that were accompanied by a contralateral distractor (Experiment 1) or an antisaccade (Experiment 2). There were no hemifield-specific effects of the reward on saccade latency on the remote distractor effect or antisaccades, although the reward was associated with an overall slowing of saccade latency in Experiment 1. These data indicate that operant conditioning of saccadic eye movements does not transfer to similar but untrained tasks. We conclude that rewarding specific spatial locations is unlikely to induce long-term, systemic changes to the human oculomotor system.

Properties of Horizontal Saccades Accompanied by Blinks

1998 ◽  
Vol 79 (6) ◽  
pp. 2895-2902 ◽  
Author(s):  
Klaus G. Rottach ◽  
Vallabh E. Das ◽  
Walter Wohlgemuth ◽  
Ari Z. Zivotofsky ◽  
R. John Leigh
Keyword(s):  
Eye Movements ◽  
Peak Velocity ◽  
Dynamic Properties ◽  
Human Subjects ◽  
Saccadic Eye Movements ◽  
Stationary Target ◽  
Normal Human ◽  
The Right ◽  
Straight Ahead ◽  
Omnipause Neurons

Rottach, Klaus G., Vallabh E. Das, Walter Wohlgemuth, Ari Z. Zivotofsky, and R. John Leigh. Properties of horizontal saccades accompanied by blinks. J. Neurophysiol. 79: 2895–2902, 1998. Using the magnetic search coil technique to record eye and lid movements, we investigated the effect of voluntary blinks on horizontal saccades in five normal human subjects. The main goal of the study was to determine whether changes in the dynamics of saccades with blinks could be accounted for by a superposition of the eye movements induced by blinks as subjects fixated a stationary target and saccadic movements made without a blink. First, subjects made voluntary blinks as they fixed on stationary targets located straight ahead or 20° to the right or left. They then made saccades between two continuously visible targets 20 or 40° apart, while either attempting not to blink, or voluntarily blinking, with each saccade. During fixation of a target located straight ahead, blinks induced brief downward and nasalward deflections of eye position. When subjects looked at targets located at right or left 20°, similar initial movements were made by four of the subjects, but the amplitude of the adducted eye was reduced by 65% and was followed by a larger temporalward movement. Blinks caused substantial changes in the dynamic properties of saccades. For 20° saccades made with blinks, peak velocity and peak acceleration were decreased by ∼20% in all subjects compared with saccades made without blinks. Blinks caused the duration of 20° saccades to increase, on average, by 36%. On the other hand, blinks had only small effects on the gain of saccades. Blinks had little influence on the relative velocities of centrifugal versus centripetal saccades, and abducting versus adducting saccades. Three of five subjects showed a significantly increased incidence of dynamic overshoot in saccades accompanied by blinks, especially for 20° movements. Taken with other evidence, this finding suggests that saccadic omnipause neurons are inhibited by blinks, which have longer duration than the saccades that company them. In conclusion, the changes in dynamic properties of saccades brought about by blinks cannot be accounted for simply by a summation of gaze perturbations produced by blinks during fixation and saccadic eye movements made without blinks. Our findings, especially the appearance of dynamic overshoots, suggest that blinks affect the central programming of saccades. These effects of blinks need to be taken into account during studies of the dynamic properties of saccades.

scholarly journals Phosphene Induction and the Generation of Saccadic Eye Movements by Striate Cortex

2005 ◽  
Vol 93 (1) ◽  
pp. 1-19 ◽  
Author(s):  
E. J. Tehovnik ◽  
W. M. Slocum ◽  
C. E. Carvey ◽  
P. H. Schiller
Keyword(s):  
Electrical Stimulation ◽  
Eye Movements ◽  
Striate Cortex ◽  
Human Subjects ◽  
Saccadic Eye Movements ◽  
Visual Prosthesis ◽  
Prosthetic Device ◽  
Electrical Microstimulation ◽  
Stimulation Parameters ◽  
Cortex Area

The purpose of this review is to critically examine phosphene induction and saccadic eye movement generation by electrical microstimulation of striate cortex (area V1) in humans and monkeys. The following issues are addressed: 1) Properties of electrical stimulation as they pertain to the activation of V1 elements; 2) the induction of phosphenes in sighted and blind human subjects elicited by electrical stimulation using various stimulation parameters and electrode types; 3) the induction of phosphenes with electrical microstimulation of V1 in monkeys; 4) the generation of saccadic eye movements with electrical microstimulation of V1 in monkeys; and 5) the tasks involved for the development of a cortical visual prosthesis for the blind. In this review it is concluded that electrical microstimulation of area V1 in trained monkeys can be used to accelerate the development of an effective prosthetic device for the blind.

Impairment of Saccadic Eye Movements by Scopolamine Treatment

1993 ◽  
Vol 76 (1) ◽  
pp. 159-167 ◽  
Author(s):  
Giulia A. Oliva ◽  
Maria P. Bucci ◽  
Roberto Fioravanti
Keyword(s):  
Eye Movements ◽  
Intramuscular Injection ◽  
Peak Velocity ◽  
Saccadic Eye Movements ◽  
Random Time ◽  
Time Interval ◽  
Random Time Interval ◽  
Standard Deviations

The effects of Scopolamine on the dynamics of saccadic eye movements, stimulated over a random time interval, have been investigated in humans. A 0.5-mg dose of the drug (intramuscular injection) had various influences on the basic saccadic parameters. For all subjects duration increased and peak velocity decreased, while for 50% of the subjects saccades became hypometric and latency increased. Standard deviations increased consistently too. Moreover, the Scopolamine treatment affected postsaccadic fixation; at the end of many saccades, the eye drifted considerably, but stability was recovered after a few seconds.

scholarly journals Express saccades and superior colliculus responses are sensitive to short-wavelength cone contrast

2016 ◽  
Vol 113 (24) ◽  
pp. 6743-6748 ◽  
Author(s):  
Nathan J. Hall ◽  
Carol L. Colby
Keyword(s):  
Eye Movements ◽  
Superior Colliculus ◽  
Short Wavelength ◽  
Human Subjects ◽  
Reaction Times ◽  
Saccadic Eye Movements ◽  
Express Saccades ◽  
Color Information ◽  
Express Saccade ◽  
Psychophysical Studies

A key structure for directing saccadic eye movements is the superior colliculus (SC). The visual pathways that project to the SC have been reported to carry only luminance information and not color information. Short-wavelength–sensitive cones (S-cones) in the retina make little or no contribution to luminance signals, leading to the conclusion that S-cone stimuli should be invisible to SC neurons. The premise that S-cone stimuli are invisible to the SC has been used in numerous clinical and human psychophysical studies. The assumption that the SC cannot use S-cone stimuli to guide behavior has never been tested. We show here that express saccades, which depend on the SC, can be driven by S-cone input. Further, express saccade reaction times and changes in SC activity depend on the amount of S-cone contrast. These results demonstrate that the SC can use S-cone stimuli to guide behavior. We conclude that the use of S-cone stimuli is insufficient to isolate SC function in psychophysical and clinical studies of human subjects.

scholarly journals Computerized Eye-Tracking Training Improves the Saccadic Eye Movements of Children with Attention-Deficit/Hyperactivity Disorder

2020 ◽  
Vol 10 (12) ◽  
pp. 1016
Author(s):  
Tsz Lok Lee ◽  
Michael K. Yeung ◽  
Sophia L. Sze ◽  
Agnes S. Chan
Keyword(s):  
Attention Deficit Hyperactivity Disorder ◽  
Eye Movements ◽  
Eye Tracking ◽  
Attention Deficit ◽  
Saccadic Eye Movements ◽  
Saccade Latency ◽  
Pharmacological Intervention ◽  
Control Group ◽  
Children With Adhd ◽  
Hyperactivity Disorder

Abnormal saccadic eye movements, such as longer anti-saccade latency and lower pro-saccade accuracy, are common in children with attention-deficit/hyperactivity disorder (ADHD). The present study aimed to investigate the effectiveness of computerized eye-tracking training on improving saccadic eye movements in children with ADHD. Eighteen children with ADHD (mean age = 8.8 years, 10 males) were recruited and assigned to either the experimental (n = 9) or control group (n = 9). The experimental group underwent an accumulated 240 min of eye-tracking training within two weeks, whereas the control group engaged in web game playing for the same amount of time. Saccadic performances were assessed using the anti- and pro-saccade tasks before and after training. Compared to the baseline, only the children who underwent the eye-tracking training showed significant improvements in saccade latency and accuracy in the anti- and pro-saccade tasks, respectively. In contrast, the control group exhibited no significant changes. These preliminary findings support the use of eye-tracking training as a safe non-pharmacological intervention for improving the saccadic eye movements of children with ADHD.

scholarly journals Anticipation of physical causality guides eye movements

2016 ◽  
Vol 9 (2) ◽  
Author(s):  
Kim Wende ◽  
Laetitia Theunissen ◽  
Marcus Missal
Keyword(s):  
Eye Movements ◽  
Moving Objects ◽  
Unique Feature ◽  
Human Subjects ◽  
Human Perception ◽  
Saccadic Eye Movements ◽  
Oculomotor System ◽  
Newtonian Mechanics ◽  
Physical Causality ◽  
Before And After

Causality is a unique feature of human perception. We present here a behavioral investigation of the influence of physical causality during visual pursuit of object collisions. Pursuit and saccadic eye movements of human subjects were recorded during ocular pursuit of two concurrently launched targets, one that moved according to the laws of Newtonian mechanics (the causal target) and the other one that moved in a physically implausible direction (the non-causal target). We found that anticipation of collision evoked early smooth pursuit decelerations. Saccades to non-causal targets were hypermetric and had latencies longer than saccades to causal targets. In conclusion, before and after a collision of two moving objects the oculomotor system implicitly predicts upcoming physically plausible target trajectories.

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