Transfer of gain changes from targeting to other types of saccade in the monkey: constraints on possible sites of saccadic gain adaptation

1996 ◽  
Vol 76 (4) ◽  
pp. 2522-2535 ◽  
Author(s):  
A. F. Fuchs ◽  
D. Reiner ◽  
M. Pong
Keyword(s):  
Optokinetic Nystagmus ◽  
Saccadic Eye Movements ◽  
Amplitude Distribution ◽  
Oculomotor System ◽  
Express Saccades ◽  
Behavioral Experiments ◽  
Average Percentage ◽  
Gain Adaptation ◽  
Gain Reduction ◽  
Visual Targets

1. Our goal was to use behavioral experiments to delimit where in the simian oculomotor system the gain of horizontal saccadic eye movements might be controlled. Our strategy was to change the gain of saccades to visual target steps (called targeting saccades) and to examine whether these changes transferred to other types of saccades. We reduced the gain of targeting saccades by jumping the target backward as a saccade was made so that the saccade appeared to overshoot. After 1,000-1,500 saccades to such backstepping targets, the average overshoot, and therefore the saccadic gain, had decreased substantially. 2. After the gain of targeting saccades had been reduced by 15-22%, several kinds of saccades were tested. Most were elicited by various visual targets. Some were made to jumping targets, which were timed to elicit saccades with longer (delayed saccades) or shorter (express saccades) latencies than normal or to targets that disappeared after a brief exposure (memory-guided saccades). Others were elicited to stationary targets (self-paced saccades) or in pursuit of a smoothly moving target (catchup saccades). Finally, we tested the saccadic fast phases of vestibular and optokinetic nystagmus. 3. Gain reduction of targeting saccades transferred at least partially to all the other types of saccades made to target jumps. The percentage gain transfer was calculated as (gain reduction of test saccades)/(gain reduction of adapted targeting saccades). The average percent transfer to delayed, memory-guided, and express saccades was 96, 88, and 91%, respectively. 4. Monkeys also showed substantial gain transfer to self-paced saccades, which scanned stationary targets. The average percentage gain transfer was 69% in the four animals tested. When two humans performed the same task, there was no transfer at all. These data suggest that saccadic gain adjustment involves different processes in monkeys and humans. 5. The transfer of gain to the catchup saccades of smooth pursuit varied from 41 to 100% across the four monkeys tested. Nevertheless, the average percentage gain transfer for all the animals was 75%. 6. As judged by the amplitude distribution of fast phases before and after adaptation, there was little, if any, saccadic gain transfer to the fast phases of vestibular or optokinetic nystagmus. In 12 of 13 experiments, there was no significant decrease in fast phase amplitude after a gain reduction of targeting saccades (P > 0.1). 7. This study shows that the average percentage gain transfer from targeting to delayed, express, memory-guided, self-paced, and catchup saccades was never < 69%. Although there was substantial transfer to saccades elicited by jumping, stationary, remembered, or slowly moving visual targets, there was relatively little to the saccadelike fast phases of nystagmus. The transfer of saccadic gain to the very short-latency express saccades suggests that adaptation modifies a subcortical locus. Moreover, the major locus must lie only in the premotor pathway for visual saccades, because saccadic gain adaptation is only poorly transferred to the fast phases of vestibular and optokinetic nystagmus.

Lesions of the posterior commissure disable the vertical neural integrator of the primate oculomotor system

1994 ◽  
Vol 71 (6) ◽  
pp. 2582-2585 ◽  
Author(s):  
A. M. Partsalis ◽  
S. M. Highstein ◽  
A. K. Moschovakis
Keyword(s):  
Eye Movements ◽  
Optokinetic Nystagmus ◽  
Head Rotation ◽  
Oculomotor System ◽  
Squirrel Monkeys ◽  
Neural Integrator ◽  
Posterior Commissure ◽  
Oculomotor Neurons ◽  
Before And After ◽  
Gain Reduction

1. Spontaneous saccades, vestibuloocular responses (VOR), and optokinetic nystagmus were recorded in three squirrel monkeys before and after chemical or electrolytic lesion of the posterior commissure (PC). 2. PC lesions produced abnormal vertical eye movements, in particular, 1) Postsaccadic drifts, and 2) VOR gain reduction and phase advance more pronounced at lower frequencies of sinusoidal head rotation. Horizontal eye movements were much less affected (or normal). 3. We conclude that PC fibers are necessary for conveying the output of the vertical neural integrator to vertical oculomotor-neurons.

Saccadic Gain Modification: Visual Error Drives Motor Adaptation

1998 ◽  
Vol 80 (5) ◽  
pp. 2405-2416 ◽  
Author(s):  
Josh Wallman ◽  
Albert F. Fuchs
Keyword(s):  
Target Location ◽  
Rhesus Macaques ◽  
Motor Adaptation ◽  
Saccadic Eye Movements ◽  
Target Distance ◽  
Error Signal ◽  
Gain Adaptation ◽  
Horizontal Saccade ◽  
Corrective Saccades ◽  
Visual Error

Wallman, Josh and Albert F. Fuchs. Saccadic gain modification: visual error drives motor adaptation. J. Neurophysiol. 80: 2405–2416, 1998. The brain maintains the accuracy of saccadic eye movements by adjusting saccadic amplitude relative to the target distance (i.e., saccade gain) on the basis of the performance of recent saccades. If an experimenter surreptitiously moves the target backward during each saccade, thereby causing the eyes to land beyond their targets, saccades undergo a gradual gain reduction. The error signal driving this conventional saccadic gain adaptation could be either visual (the postsaccadic distance of the target from the fovea) or motoric (the direction and size of the corrective saccade that brings the eye onto the back-stepped target). Similarly, the adaptation itself might be a motor adjustment (change in the size of saccade for a given perceived target distance) or a visual remapping (change in the perceived target distance). We studied these possibilities in experiments both with rhesus macaques and with humans. To test whether the error signal is motoric, we used a paradigm devised by Heiner Deubel. The Deubel paradigm differed from the conventional adaptation paradigm in that the backward step that occurred during the saccade was brief, and the target then returned to its original displaced location. This ploy replaced most of the usual backward corrective saccades with forward ones. Nevertheless, saccadic gain gradually decreased over hundreds of trials. Therefore, we conclude that the direction of saccadic gain adaptation is not determined by the direction of corrective saccades. To test whether gain adaptation is a manifestation of a static visual remapping, we decreased the gain of 10° horizontal saccades by conventional adaptation and then tested the gain to targets appearing at retinal locations unused during adaptation. To make the target appear in such “virgin territory,” we had it jump first vertically and then 10° horizontally; both jumps were completed and the target spot extinguished before saccades were made sequentially to the remembered target locations. Conventional adaptation decreased the gain of the second, horizontal saccade even though the target was in a nonadapted retinal location. In contrast, the horizontal component of oblique saccades made directly to the same virgin location showed much less gain decrease, suggesting that the adaptation is specific to saccade direction rather than to target location. Thus visual remapping cannot account for the entire reduction of saccadic gain. We conclude that saccadic gain adaptation involves an error signal that is primarily visual, not motor, but that the adaptation itself is primarily motor, not visual.

Sound-Localization Performance in the Cat: The Effect of Restraining the Head

2005 ◽  
Vol 93 (3) ◽  
pp. 1223-1234 ◽  
Author(s):  
Daniel J. Tollin ◽  
Luis C. Populin ◽  
Jordan M. Moore ◽  
Janet L. Ruhland ◽  
Tom C. T. Yin
Keyword(s):  
Short Duration ◽  
Saccadic Eye Movements ◽  
Head Movements ◽  
Gaze Shifts ◽  
Localization Accuracy ◽  
Head Restraint ◽  
The Gaze ◽  
Long Duration ◽  
Localization Performance ◽  
Visual Targets

In oculomotor research, there are two common methods by which the apparent location of visual and/or auditory targets are measured, saccadic eye movements with the head restrained and gaze shifts (combined saccades and head movements) with the head unrestrained. Because cats have a small oculomotor range (approximately ±25°), head movements are necessary when orienting to targets at the extremes of or outside this range. Here we tested the hypothesis that the accuracy of localizing auditory and visual targets using more ethologically natural head-unrestrained gaze shifts would be superior to head-restrained eye saccades. The effect of stimulus duration on localization accuracy was also investigated. Three cats were trained using operant conditioning with their heads initially restrained to indicate the location of auditory and visual targets via eye position. Long-duration visual targets were localized accurately with little error, but the locations of short-duration visual and both long- and short-duration auditory targets were markedly underestimated. With the head unrestrained, localization accuracy improved substantially for all stimuli and all durations. While the improvement for long-duration stimuli with the head unrestrained might be expected given that dynamic sensory cues were available during the gaze shifts and the lack of a memory component, surprisingly, the improvement was greatest for the auditory and visual stimuli with the shortest durations, where the stimuli were extinguished prior to the onset of the eye or head movement. The underestimation of auditory targets with the head restrained is explained in terms of the unnatural sensorimotor conditions that likely result during head restraint.

scholarly journals Apparent Position of Visual Targets during Real and Simulated Saccadic Eye Movements

1997 ◽  
Vol 17 (20) ◽  
pp. 7941-7953 ◽  
Author(s):  
M. Concetta Morrone ◽  
John Ross ◽  
David C. Burr
Keyword(s):  
Eye Movements ◽  
Saccadic Eye Movements ◽  
Apparent Position ◽  
Visual Targets

scholarly journals Target modality determines eye-head coordination in nonhuman primates: implications for gaze control

2011 ◽  
Vol 106 (4) ◽  
pp. 2000-2011 ◽  
Author(s):  
Luis C. Populin ◽  
Abigail Z. Rajala
Keyword(s):  
Nonhuman Primates ◽  
Saccadic Eye Movements ◽  
Head Movements ◽  
Gaze Shifts ◽  
Gaze Shift ◽  
The Gaze ◽  
Midbrain Structure ◽  
The Subject ◽  
Visual Targets ◽  
Time Of Presentation

We have studied eye-head coordination in nonhuman primates with acoustic targets after finding that they are unable to make accurate saccadic eye movements to targets of this type with the head restrained. Three male macaque monkeys with experience in localizing sounds for rewards by pointing their gaze to the perceived location of sources served as subjects. Visual targets were used as controls. The experimental sessions were configured to minimize the chances that the subject would be able to predict the modality of the target as well as its location and time of presentation. The data show that eye and head movements are coordinated differently to generate gaze shifts to acoustic targets. Chiefly, the head invariably started to move before the eye and contributed more to the gaze shift. These differences were more striking for gaze shifts of <20–25° in amplitude, to which the head contributes very little or not at all when the target is visual. Thus acoustic and visual targets trigger gaze shifts with different eye-head coordination. This, coupled to the fact that anatomic evidence involves the superior colliculus as the link between auditory spatial processing and the motor system, suggests that separate signals are likely generated within this midbrain structure.

Saccadic Eye Movements of Dyslexic and Normal Reading Children

Perception ◽  
1994 ◽  
Vol 23 (1) ◽  
pp. 45-64 ◽  
Author(s):  
Monica Biscaldi ◽  
Burkhart Fischer ◽  
Franz Aiple
Keyword(s):  
Eye Movements ◽  
Reaction Times ◽  
Saccadic Eye Movements ◽  
Control Group ◽  
Express Saccades ◽  
Movement Data ◽  
Fixation Durations ◽  
Normal Reading ◽  
Single Target ◽  
The Right

Twenty-four children made saccades in five noncognitive tasks. Two standard tasks required saccades to a single target presented randomly 4 deg to the right or left of a fixation point. Three other tasks required sequential saccades from the left to the right. 75 parameters of the eye-movement data were collected for each child. On the basis of their reading, writing, and other cognitive performances, twelve children were considered dyslexic and were divided into two groups (D1 and D2). Group statistical comparisons revealed significant differences between control and dyslexic subjects. In general, in the standard tasks the dyslexic subjects had poorer fixation quality, failed more often to hit the target at once, had smaller primary saccades, and had shorter reaction times to the left as compared with the control group. The control group and group D1 dyslexics showed an asymmetrical distribution of reaction times, but in opposite directions. Group D2 dyslexics made more anticipatory and express saccades, they undershot the target more often in comparison with the control group, and almost never overshot it. In the sequential tasks group D1 subjects made fewer and larger saccades in a shorter time and group D2 subjects had shorter fixation durations than the subjects of the control group.

scholarly journals Time course of spatiotopic updating across saccades

2019 ◽  
Vol 116 (6) ◽  
pp. 2027-2032 ◽  
Author(s):  
Jasper H. Fabius ◽  
Alessio Fracasso ◽  
Tanja C. W. Nijboer ◽  
Stefan Van der Stigchel
Keyword(s):  
Eye Movements ◽  
Visual System ◽  
Eye Movement ◽  
Time Course ◽  
Saccadic Eye Movements ◽  
Oculomotor System ◽  
Stimulus Onset ◽  
Oculomotor Behavior ◽  
Behavioral Studies ◽  
The Brain

Humans move their eyes several times per second, yet we perceive the outside world as continuous despite the sudden disruptions created by each eye movement. To date, the mechanism that the brain employs to achieve visual continuity across eye movements remains unclear. While it has been proposed that the oculomotor system quickly updates and informs the visual system about the upcoming eye movement, behavioral studies investigating the time course of this updating suggest the involvement of a slow mechanism, estimated to take more than 500 ms to operate effectively. This is a surprisingly slow estimate, because both the visual system and the oculomotor system process information faster. If spatiotopic updating is indeed this slow, it cannot contribute to perceptual continuity, because it is outside the temporal regime of typical oculomotor behavior. Here, we argue that the behavioral paradigms that have been used previously are suboptimal to measure the speed of spatiotopic updating. In this study, we used a fast gaze-contingent paradigm, using high phi as a continuous stimulus across eye movements. We observed fast spatiotopic updating within 150 ms after stimulus onset. The results suggest the involvement of a fast updating mechanism that predictively influences visual perception after an eye movement. The temporal characteristics of this mechanism are compatible with the rate at which saccadic eye movements are typically observed in natural viewing.

Hysteresis and slow drift in abducens unit activity

1986 ◽  
Vol 55 (5) ◽  
pp. 1044-1056 ◽  
Author(s):  
H. P. Goldstein ◽  
D. A. Robinson
Keyword(s):  
Steady State ◽  
Eye Movements ◽  
Firing Rate ◽  
Visual Target ◽  
Saccadic Eye Movements ◽  
Oculomotor System ◽  
Primary Position ◽  
Background Rate ◽  
Slow Drift ◽  
Theoretical Question

Two trained monkeys made saccadic eye movements to a small visual target. The activity of 39 isolated abducens units, presumed to be motoneurons or abducens internuclear neurons, was recorded in relation to these eye movements. After a calibration trial, a test trial repeatedly elicited 20 degrees horizontal saccades to primary position from either the left or right. On average, the steady-state firing rate at primary position depended on the direction of the saccade. For saccades where the neuron showed a burst in activity during the saccade (on-saccades) the steady-state firing rates were usually higher than for those saccades that showed a pause in activity during the saccade (off-saccades). For the population of units this hysteresis measured 5.4 spikes/s, which may be compared with an average primary-position rate of 97 spikes/s. The average hysteresis for individual units ranged from -2.1 to 18.5 spikes/s. The steady-state firing rate after equal saccades in the same direction and ending at the same position (primary) varied slowly over time. Across all units the variability (standard deviation) ranged from 0.5 to 11.8 spikes/s with a mean of 4.7 spikes/s. Furthermore, for any one unit the variations following on-saccades generally correlated with the variations following the off-saccades. Hysteresis, doubted by many, does exist. Fortunately, it is small enough, 5.5% of typical primary-position rate, that it can be neglected for many purposes. Nevertheless, it poses the interesting theoretical question of how the oculomotor system compensates for hysteresis. The simplest explanation of slow variations in background rate is cocontractive noise: a slow fluctuation in all abducens neurons so that these variations do not result in fluctuations of eye position.

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