Properties of signals that determine the amplitude and direction of saccadic eye movements in monkeys

1986 ◽  
Vol 56 (1) ◽  
pp. 196-207 ◽  
Author(s):  
A. McKenzie ◽  
S. G. Lisberger
Keyword(s):  
Eye Movements ◽  
Saccadic Eye Movements ◽  
Head Movements ◽  
Polar Coordinates ◽  
Eye Position ◽  
Spatial Error ◽  
Internal Feedback ◽  
The Neural Network ◽  
Smooth Change ◽  
Highly Correlated

Monkeys were trained to make saccades to briefly flashed targets. We presented the flash during smooth pursuit of another target, so that there was a smooth change in eye position after the flash. We could then determine whether the flash-evoked saccades compensated for the intervening smooth eye movements to point the eyes at the position of the flash in space. We defined the "retinal error" as the vector from the position of the eye at the time of the flash to the position of the target. We defined "spatial error" as the vector from the position of the eye at the time of the saccade to the position of the flashed target in space. The direction of the saccade (in polar coordinates) was more highly correlated with the direction of the retinal error than with the direction of the spatial error. Saccade amplitude was also better correlated with the amplitude of the retinal error. We obtained the same results whether the flash was presented during pursuit with the head fixed or during pursuit with combined eye-head movements. Statistical analysis demonstrated that the direction of the saccade was determined only by the retinal error in two of the three monkeys. In the third monkey saccade direction was determined primarily by retinal error but had a consistent bias toward spatial error. The bias can be attributed to this monkey's earlier practice in which the flashed target was reilluminated so he could ultimately make a saccade to the correct position in space. These data suggest that the saccade generator does not normally use nonvisual feedback about smooth changes in eye or gaze position. In two monkeys we also provided sequential target flashes during pursuit with the second flash timed so that it occurred just before the first saccade. As above, the first saccade was appropriate for the retinal error provided by the first flash. The second saccade compensated for the first and pointed the eyes at the position of the second target in space. We conclude, as others have before (12, 21), that the saccade generator receives feedback about its own output, saccades. Our results require revision of existing models of the neural network that generates saccades. We suggest two models that retain the use of internal feedback suggested by others. We favor a model that accounts for our data by assuming that internal feedback originates directly from the output of the saccade generator and reports only saccadic changes in eye position.

scholarly journals Saccadic eye movements are coordinated with head movements in walking chickens

1982 ◽  
Vol 97 (1) ◽  
pp. 217-223
Author(s):  
D. W. Pratt
Keyword(s):  
Eye Movements ◽  
Saccadic Eye Movements ◽  
Head Movements ◽  
Clear Vision ◽  
Head Bobbing ◽  
Insufficient Time ◽  
Made In

1. Saccadic eye movements during walking were studied in chickens using cinematography. 2. Saccades were made during about 80% of the thrust phases of head bobbing, and not made in the hold phases. 3. The coordination of saccades with head movements maintains clear vision for the largest possible proportion of the time. 4. The absence of saccades in hold phases and in some thrusts is probably not the result of insufficient time to organize a saccade.

Use of interrupted saccade paradigm to study spatial and temporal dynamics of saccadic burst cells in superior colliculus in monkey

1994 ◽  
Vol 72 (6) ◽  
pp. 2754-2770 ◽  
Author(s):  
E. L. Keller ◽  
J. A. Edelman
Keyword(s):  
Eye Movements ◽  
Superior Colliculus ◽  
Temporal Dynamics ◽  
Saccadic Eye Movements ◽  
Eye Position ◽  
Visual Response ◽  
Intermediate Layers ◽  
Saccade Onset ◽  
Spatial And Temporal Dynamics ◽  
Motor Error

1. We recorded the spatial and temporal dynamics of saccade-related burst neurons (SRBNs) found in the intermediate layers of the superior colliculus (SC) in the alert, behaving monkey. These burst cells are normally the first neurons recorded during radially directed microelectrode penetrations of the SC after the electrode has left the more dorsally situated visual layers. They have spatially delimited movement fields whose centers describe the well-studied motor map of the SC. They have a rather sharp, saccade-locked burst of activity that peaks just before saccade onset and then declines steeply during the saccade. Many of these cells, when recorded during saccade trials, also have an early, transient visual response and an irregular prelude of presaccadic activity. 2. Because saccadic eye movements normally have very stereotyped durations and velocity trajectories that vary systematically with saccade size, it has been difficult in the past to establish quantitatively whether the activity of SRBNs temporally codes dynamic saccadic control signals, e.g., dynamic motor error or eye velocity, where dynamic motor error is defined as a signal proportional to the instantaneous difference between desired final eye position and the actual eye position during a saccade. It has also not been unequivocally established whether SRBNs participate in an organized spatial shift of ensemble activity in the intermediate layers of the SC during saccadic eye movements. 3. To address these issues, we studied the activity of SRBNs using an interrupted saccade paradigm. Saccades were interrupted with pulsatile electrical stimulation through a microelectrode implanted in the omnipauser region of the brain stem while recordings were made simultaneously from single SRBNs in the SC. 4. Shortly after the beginning of the stimulation (which was electronically triggered at saccade onset), the eyes decelerated rapidly and stopped completely. When the high-frequency (typically 300-400 pulses per second) stimulation was terminated (average duration 12 ms), the eye movement was reinitiated and a resumed saccade was made accurately to the location of the target. 5. When we recorded from SRBNs in the more caudal colliculus, which were active for large saccades, cell discharge was powerfully and rapidly suppressed by the stimulation (average latency = 3.8 ms). Activity in the same cells started again just before the onset of the resumed saccade and continued during this saccade even though it has a much smaller amplitude than would normally be associated with significant discharge for caudal SC cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Eye position effects in saccadic adaptation

2011 ◽  
Vol 106 (5) ◽  
pp. 2536-2545 ◽  
Author(s):  
Katharina Havermann ◽  
Eckart Zimmermann ◽  
Markus Lappe
Keyword(s):  
Eye Movements ◽  
Visual Space ◽  
Initial Position ◽  
Head Movements ◽  
Eye Position ◽  
Saccade Amplitude ◽  
Position Effects ◽  
Position Information ◽  
Saccadic Adaptation ◽  
Visual Error

Saccades are used by the visual system to explore visual space with the high accuracy of the fovea. The visual error after the saccade is used to adapt the control of subsequent eye movements of the same amplitude and direction in order to keep saccades accurate. Saccadic adaptation is thus specific to saccade amplitude and direction. In the present study we show that saccadic adaptation is also specific to the initial position of the eye in the orbit. This is useful, because saccades are normally accompanied by head movements and the control of combined head and eye movements depends on eye position. Many parts of the saccadic system contain eye position information. Using the intrasaccadic target step paradigm, we adaptively reduced the amplitude of reactive saccades to a suddenly appearing target at a selective position of the eyes in the orbitae and tested the resulting amplitude changes for the same saccade vector at other starting positions. For central adaptation positions the saccade amplitude reduction transferred completely to eccentric starting positions. However, for adaptation at eccentric starting positions, there was a reduced transfer to saccades from central starting positions or from eccentric starting positions in the opposite hemifield. Thus eye position information modifies the transfer of saccadic amplitude changes in the adaptation of reactive saccades. A gain field mechanism may explain the eye position dependence found.

scholarly journals Coupling Between Horizontal and Vertical Components of Saccadic Eye Movements During Constant Amplitude and Direction Gaze Shifts in the Rhesus Monkey

2008 ◽  
Vol 100 (6) ◽  
pp. 3375-3393 ◽  
Author(s):  
Edward G. Freedman
Keyword(s):  
Eye Movements ◽  
Saccadic Eye Movements ◽  
Head Movements ◽  
Horizontal Meridian ◽  
Constant Amplitude ◽  
Saccade Amplitude ◽  
Gaze Shifts ◽  
Horizontal Saccade ◽  
Vertical Saccade ◽  
Saccade Duration

When the head is free to move, changes in the direction of the line of sight (gaze shifts) can be accomplished using coordinated movements of the eyes and head. During repeated gaze shifts between the same two targets, the amplitudes of the saccadic eye movements and movements of the head vary inversely as a function of the starting positions of the eyes in the orbits. In addition, as head-movement amplitudes and velocities increase, saccade velocities decline. Taken together these observations lead to a reversal in the expected correlation between saccade duration and amplitude: small-amplitude saccades associated with large head movements can have longer durations than larger-amplitude saccades associated with small head movements. The data in this report indicate that this reversal occurs during gaze shifts along the horizontal meridian and also when considering the horizontal component of oblique saccades made when the eyes begin deviated only along the horizontal meridian. Under these conditions, it is possible to determine whether the variability in the duration of the constant amplitude vertical component of oblique saccades is accounted for better by increases in horizontal saccade amplitude or increases in horizontal saccade duration. Results show that vertical saccade duration can be inversely related to horizontal saccade amplitude (or unrelated to it) but that horizontal saccade duration is an excellent predictor of vertical saccade duration. Modifications to existing hypotheses of gaze control are assessed based on these new observations and a mechanism is proposed that can account for these data.

Effects of eye position on electrically evoked saccades: a theoretical note

1988 ◽  
Vol 1 (2) ◽  
pp. 239-244 ◽  
Author(s):  
James T. McIlwain
Keyword(s):  
Eye Movements ◽  
Internal Representation ◽  
Target Position ◽  
Saccadic Eye Movements ◽  
Brain Structures ◽  
Initial Position ◽  
Eye Position ◽  
Saccadic System ◽  
Early Processing ◽  
The Difference

AbstractThe trajectories of saccadic eye movements evoked electrically from many brain structures are dependent to some degree on the initial position of the eye. Under certain conditions, likely to occur in stimulation experiments, local feedback models of the saccadic system can yield eye movements which behave in this way. The models in question assume that an early processing stage adds an internal representation of eye position to retinal error to yield a signal representing target position with respect to the head. The saccadic system is driven by the difference between this signal and one representing the current position of the eye. Albano & Wurtz (1982) pointed out that lesions perturbing the computation of eye position with respect to the head can result in initial position dependence of visually evoked saccades. It is shown here that position-dependent saccades will also result if electrical stimulation evokes a signal equivalent to retinal error but fails to effect a complete addition of eye position to this signal. Also, when multiple or staircase saccades are produced, as during long stimulus trains, they will have identical directions but decrease progressively in amplitude by a factor related to the fraction of added eye position.

Learning and Maintaining Saccadic Accuracy: A Model of Brainstem–Cerebellar Interactions

1994 ◽  
Vol 6 (2) ◽  
pp. 117-138 ◽  
Author(s):  
Paul Dean ◽  
John E. W. Mayhew ◽  
Pat Langdon
Keyword(s):  
Eye Movements ◽  
Superior Colliculus ◽  
Motor Neurons ◽  
Feedback Controller ◽  
Functional Explanation ◽  
Eye Position ◽  
Error Signal ◽  
Internal Feedback ◽  
Eye Muscles ◽  
Oculomotor Vermis

Saccadic accuracy requires that the control signal sent to the motor neurons must be the right size to bring the fovea to the target, whatever the initial position of the eyes (and corresponding state of the eye muscles). Clinical and experimental evidence indicates that the basic machinery for generating saccadic eye movements, located in the brainstem, is not accurate: learning to make accurate saccades requires cerebellar circuitry located in the posterior vermis and fastigial nucleus. How do these two circuits interact to achieve adaptive control of saccades? A model of this interaction is described, based on Kawato's principle of feedback-error-learning. Its three components were (1) a simple controller with no knowledge of initial eye position, corresponding to the superior colliculus; (2) Robinson's internal feedback model of the saccadic burst generator, corresponding to preoculomotor areas in the brain-stem; and (3) Albus's Cerebellar Model Arithmetic Computer (CMK), a neural net model of the cerebellum. The connections between these components were (I) the simple feedback controller passed a (usually inaccurate) command to the pulse generator, and (2) a copy of this command to the CMAC; (3) the CMAC combined the copy with information about initial eye position to (4) alter the gain on the pulse generator's internal feedback loop, thereby adjusting the size of burst sent to the motor neurons. (5) If the saccade were inaccurate, an error signal from the feedback controller adjusted the weights in the CMAC. It was proposed that connection (2) corresponds to the mossy fiber projection from superior colliculus to oculomotor vermis via the nucleus reticularis tegmenti pontis, and connection (5) to the climbing fiber projection from superior colliculus to the oculomotor vermis via the inferior olive. Plausible initialization values were chosen so that the system produced hypometric saccades (as do human infants) at the start of learning, and position-dependent hypermetric saccades when the cerebellum was removed. Simulations for horizontal eye movements showed that accurate saccades from any starting position could be learned rapidly, even if the error signal conveyed only whether the initial saccade were too large or too small. In subsequent tests the model adapted realistically both to simulated weakening of the eye muscles, and to intrasaccadic displacement of the target, thereby mimicking saccadic plasticity in adults. The architecture of the model may therefore offer a functional explanation of hitherto mysterious tectocerebellar projections, and a framework for investigating in greater detail how the cerebellum adaptively controls saccadic accuracy.

scholarly journals Mice Make Targeted Saccades

2021 ◽  
Author(s):  
Sebastian H. Zahler ◽  
David E. Taylor ◽  
Julia M. Adams ◽  
Evan H. Feinberg
Keyword(s):  
Eye Movements ◽  
Visual Field ◽  
Visual System ◽  
Neural Circuit ◽  
Saccadic Eye Movements ◽  
Eye Position ◽  
Innate Behavior ◽  
High Acuity ◽  
Early Origin ◽  
Innate Ability

AbstractHumans read text, recognize faces, and process emotions using targeted saccadic eye movements. In the textbook model, this innate ability to make targeted saccades evolved in species with foveae or similar high-acuity retinal specializations that enable scrutiny of salient stimuli. According to the model, saccades made by species without retinal specializations (such as mice) are never targeted and serve only to reset the eyes after gaze-stabilizing movements. Here we show that mice innately make touch-evoked targeted saccades. Optogenetic manipulations revealed the neural circuit mechanisms underlying targeted saccades are conserved. Saccade probability is a U-shaped function of current eye position relative to the target, mirroring the simulated relationship between an object’s location within the visual field and the probability its next movement carries it out of view. Thus, a cardinal sophistication of our visual system may have had an unexpectedly early origin as an innate behavior that keeps stimuli in view.

Context-specific adaptation of saccade gain in parabolic flight

2003 ◽  
Vol 12 (5-6) ◽  
pp. 211-221 ◽  
Author(s):  
Mark Shelhamer ◽  
Richard A. Clendaniel ◽  
Dale C. Roberts
Keyword(s):  
Eye Movements ◽  
Parabolic Flight ◽  
Saccadic Eye Movements ◽  
Head Orientation ◽  
Eye Position ◽  
Vestibular Reflexes ◽  
Specific Adaptation ◽  
Gravitoinertial Force ◽  
Context Specific ◽  
Saccade Adaptation

Previous studies established that vestibular reflexes can have two adapted states (e.g., gains) simultaneously, and that a context cue (e.g., vertical eye position) can switch between the two states. Our earlier work demonstrated this phenomenon of context-specific adaptation for saccadic eye movements: we asked for gain decrease in one context state and gain increase in another context state, and then determined if a change in the context state would invoke switching between the adapted states. Horizontal and vertical eye position and head orientation could serve, to varying degrees, as cues for switching between two different saccade gains. In the present study, we asked whether gravity magnitude could serve as a context cue: saccade adaptation was performed during parabolic flight, which provides alternating levels of gravitoinertial force (0 g and 1.8 g). Results were less robust than those from ground experiments, but established that different saccade magnitudes could be associated with different gravity levels.

Subcortical contributions to head movements in macaques. I. Contrasting effects of electrical stimulation of a medial pontomedullary region and the superior colliculus

1994 ◽  
Vol 72 (6) ◽  
pp. 2648-2664 ◽  
Author(s):  
R. J. Cowie ◽  
D. L. Robinson
Keyword(s):  
Electrical Stimulation ◽  
Eye Movements ◽  
Superior Colliculus ◽  
Head Movement ◽  
Saccadic Eye Movements ◽  
Head Movements ◽  
Reticular Nucleus ◽  
Gaze Shifts ◽  
Gigantocellular Reticular Nucleus ◽  
External Events

1. These studies were initiated to understand the neural sites and mechanisms controlling head movements during gaze shifts. Gaze shifts are made by saccadic eye movements with and without head movements. Sites were stimulated electrically within the brain stem of awake, trained monkeys relatively free to make head movements to study the head-movement components of gaze shifts. 2. Electrical stimulation in and around the gigantocellular reticular nucleus evoked head movements in the ipsilateral direction. Gaze shifts were never evoked from these sites, presumably because the vestibulo-ocular reflex compensated. The rough topography of this region included large head movements laterally, small movements medially, downward movements from dorsal sites, and upward movements more ventrally. 3. The initial position of the head influenced the magnitude of the elicited movement with larger movements produced when the head was directed to the contralateral side. Attentive fixation was associated with larger and faster head movements when compared with those evoked during spontaneous behavior. 4. The superior colliculus makes a significant contribution to gaze shifts and has been shown to contribute to head movements. Because the colliculus is a major source of afferents to the gigantocellular reticular nucleus, comparable stimulation studies of the superior colliculus were conducted. When the colliculus was excited, shifts of gaze in the contralateral direction were predominant. These were most often accomplished by saccadic eye movements, however, we frequently elicited head movements that had an average latency 10 ms longer than those elicited from the reticular head movement region. Sites evoking head movements tended to be deeper and more caudal than loci eliciting eye movements. Neither the onset latencies, amplitudes, nor peak velocities of head movements and eye movements were correlated. Gaze shifts evoked from the caudal colliculus with the head free were larger than those elicited from the same site with the head fixed. 5. These studies demonstrate that both the superior colliculus and gigantocellular reticular nucleus mediate head movements. The colliculus plays a role in orienting to external events, and so collicular head movements predominantly were associated with gaze shifts, with the eye and head movements uncoupled. The medullary reticular system may play a role in the integration of a wider range of movements. Head movements from the medullary reticular sites probably participate in several forms of head movements, such as those that are related to postural reflexes, started volitionally, and/or oriented to external events.

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