scholarly journals The coordination of eyes, head and trunk in very large natural gaze saccades

2004 ◽  
Vol 4 (8) ◽  
pp. 111-111
Author(s):  
M. F. Land
Keyword(s):  
Gaze Saccades

Brain Stem Omnipause Neurons and the Control of CombinedEye-Head Gaze Saccades in the Alert Cat

1998 ◽  
Vol 79 (6) ◽  
pp. 3060-3076 ◽  
Author(s):  
Martin Paré ◽  
Daniel Guitton
Keyword(s):  
Gaze Control ◽  
Error Signal ◽  
Gaze Shifts ◽  
Gaze Shift ◽  
The Gaze ◽  
Alert Cat ◽  
Motor Error ◽  
Omnipause Neurons ◽  
Gaze Saccades ◽  
Stimulation Of

Paré, Martin and Daniel Guitton. Brain stem omnipause neurons and the control of combined eye-head gaze saccades in the alert cat. J. Neurophysiol. 79: 3060–3076, 1998. When the head is unrestrained, rapid displacements of the visual axis—gaze shifts (eye-re-space)—are made by coordinated movements of the eyes (eye-re-head) and head (head-re-space). To address the problem of the neural control of gaze shifts, we studied and contrasted the discharges of omnipause neurons (OPNs) during a variety of combined eye-head gaze shifts and head-fixed eye saccades executed by alert cats. OPNs discharged tonically during intersaccadic intervals and at a reduced level during slow perisaccadic gaze movements sometimes accompanying saccades. Their activity ceased for the duration of the saccadic gaze shifts the animal executed, either by head-fixed eye saccades alone or by combined eye-head movements. This was true for all types of gaze shifts studied: active movements to visual targets; passive movements induced by whole-body rotation or by head rotation about stationary body; and electrically evoked movements by stimulation of the caudal part of the superior colliculus (SC), a central structure for gaze control. For combined eye-head gaze shifts, the OPN pause was therefore not correlated to the eye-in-head trajectory. For instance, in active gaze movements, the end of the pause was better correlated with the gaze end than with either the eye saccade end or the time of eye counterrotation. The hypothesis that cat OPNs participate in controlling gaze shifts is supported by these results, and also by the observation that the movements of both the eyes and the head were transiently interrupted by stimulation of OPNs during gaze shifts. However, we found that the OPN pause could be dissociated from the gaze-motor-error signal producing the gaze shift. First, OPNs resumed discharging when perturbation of head motion briefly interrupted a gaze shift before its intended amplitude was attained. Second, stimulation of caudal SC sites in head-free cat elicited large head-free gaze shifts consistent with the creation of a large gaze-motor-error signal. However, stimulation of the same sites in head-fixed cat produced small “goal-directed” eye saccades, and OPNs paused only for the duration of the latter; neither a pause nor an eye movement occurred when the same stimulation was applied with the eyes at the goal location. We conclude that OPNs can be controlled by neither a simple eye control system nor an absolute gaze control system. Our data cannot be accounted for by existing models describing the control of combined eye-head gaze shifts and therefore put new constraints on future models, which will have to incorporate all the various signals that act synergistically to control gaze shifts.

Cerebellar contribution to the spatial encoding of orienting gaze shifts in the head-free cat

1994 ◽  
Vol 72 (5) ◽  
pp. 2547-2550 ◽  
Author(s):  
L. Goffart ◽  
D. Pelisson
Keyword(s):  
Constant Error ◽  
Visual Target ◽  
Fastigial Nucleus ◽  
Caudal Part ◽  
Gaze Shifts ◽  
Neural Processes ◽  
Correct Execution ◽  
Gaze Position ◽  
Gaze Saccades ◽  
Saccadic Dysmetria

1. Cerebellar saccadic dysmetria may result from a disturbance in the processes that ensure correct execution of gaze displacement. Alternatively, an impairment in the preparatory processes that lead to the specification of the movement goal may also produce this deficit. 2. We report here on a pharmacologically induced dysmetria that suggests a cerebellar contribution to the neural processes encoding the location of the goal for orienting gaze shifts. 3. Shifts of gaze (eye-in-space) were recorded in the head-free cat after the GABA agonist muscimol was unilaterally injected into the caudal part of the fastigial nucleus. 4. Gaze saccades towards the inactivated side were hypermetric. These ipsiversive movements overshot the target by a constant error, regardless of target eccentricity and initial gaze position. 5. Gaze saccades directed away from the inactivated side undershot the target. The degree of hypometria increased when the amplitude of the required movement increased. 6. These results suggest a different contribution of the caudal fastigial nucleus to the accuracy of visually triggered gaze shifts, depending on the direction of the impending saccade. The systematic error of ipsiversive movements and the inappropriate movements evoked by presenting a target at the same physical location as gaze reveal that fastigial inactivation interfered with the processes that encode the location of a visual target.

Combined eye-head gaze shifts in the primate. I. Metrics

1986 ◽  
Vol 56 (6) ◽  
pp. 1542-1557 ◽  
Author(s):  
R. D. Tomlinson ◽  
P. S. Bahra
Keyword(s):  
Head Movement ◽  
Velocity Profiles ◽  
Hyperbolic Function ◽  
Total Change ◽  
Gaze Shifts ◽  
Gaze Shift ◽  
Velocity Amplitude ◽  
The Gaze ◽  
Gaze Saccades ◽  
Gaze Angle

Gaze (eye-in-space) velocity-duration and velocity-amplitude curves were prepared for head-fixed and head-free gaze shifts in the rhesus monkey with an emphasis on large amplitudes. These plots revealed the presence of two distinct gaze reorientation mechanisms, one used when the gaze shift was small (less than 20 degrees) and the other utilized for large coordinated gaze shifts when the head was free. When head-free and head-fixed saccadic gaze shifts were compared in the same animal, no differences in the metrics were found for amplitudes less than 20 degrees. However, for large gaze shifts where contribution of the head to the change in gaze angle was considerable, head-free saccades were found to exhibit lower peak gaze velocities and greater durations than those recorded with the head-fixed paradigm. In order to differentiate between the eye saccades and combined saccadic eye-head gaze shifts, the latter have been termed gaze saccades. Change in head position and change in eye position were both measured during the actual gaze shift and were plotted against the gaze-shift amplitude to determine whether the head movement contributed significantly to the change in gaze angle. The results indicate that below 20 degrees the gaze shift is accomplished almost exclusively with the eyes and the head moves very little; however, for larger saccades, the head contributes approximately 80% of the total change in gaze angle with the eyes contributing only approximately 20%. Large saccadic eye-head gaze shifts do not exhibit 'bell-shaped' velocity profiles as do smaller head-fixed saccades; instead, gaze accelerates to reach a peak velocity after approximately 30-40 ms. This velocity is then maintained for the duration of the gaze shift. Close scrutiny of the fine structure of the velocity profiles of the eye, head, and gaze channels indicates that during gaze saccades, the eye and head movement motor programs interact to maintain gaze velocity nearly constant, unaffected by changes in head velocity. Previous authors had stated that when velocity-duration plots are obtained for oblique saccades of constant amplitude, the resulting points could be fitted with a hyperbolic function. These results were confirmed for head-free gaze saccades and extended to larger amplitudes. When an oblique saccade is made, the smaller component is stretched in duration to match the duration of the larger component. However, as the gaze shift becomes large (greater than 40 degrees), the relationship becomes more complex.(ABSTRACT TRUNCATED AT 400 WORDS)

Difference Between Visually and Electrically Evoked Gaze Saccades Disclosed by Altering the Head Moment of Inertia

2000 ◽  
Vol 83 (2) ◽  
pp. 1103-1107 ◽  
Author(s):  
Alexandre J. F. Coimbra ◽  
Philippe Lefèvre ◽  
Marcus Missal ◽  
Etienne Olivier
Keyword(s):  
Head Movements ◽  
Moment Of Inertia ◽  
Gaze Shifts ◽  
Feedback Information ◽  
Slowing Down ◽  
Movement Dynamics ◽  
On Line ◽  
Gaze Saccades ◽  
Visually Evoked Saccades

Differences between gaze shifts evoked by collicular electrical stimulation and those triggered by the presentation of a visual stimulus were studied in head-free cats by increasing the head moment of inertia. This maneuver modified the dynamics of these two types of gaze shifts by slowing down head movements. Such an increase in the head moment of inertia did not affect the metrics of visually evoked gaze saccades because their duration was precisely adjusted to compensate for these changes in movement dynamics. In contrast, the duration of electrically evoked gaze shifts remained constant irrespective of the head moment of inertia, and therefore their amplitude was significantly reduced. These results suggest that visually and electrically evoked gaze saccades are controlled by different mechanisms. Whereas the accuracy of visually evoked saccades is likely to be assured by on-line feedback information, the absence of duration adjustment in electrically evoked gaze shifts suggests that feedback information necessary to maintain their metrics is not accessible or is corrupted during collicular stimulation. This is of great importance when these two types of movements are compared to infer the role of the superior colliculus in the control of orienting gaze shifts.

Firing Behavior of Vestibular Neurons During Active and Passive Head Movements: Vestibulo-Spinal and Other Non-Eye-Movement Related Neurons

1999 ◽  
Vol 82 (1) ◽  
pp. 416-428 ◽  
Author(s):  
Robert A. McCrea ◽  
Greg T. Gdowski ◽  
Richard Boyle ◽  
Timothy Belton
Keyword(s):  
Electrical Stimulation ◽  
Eye Movement ◽  
Head Rotation ◽  
Head Movements ◽  
Whole Body ◽  
Body Rotation ◽  
Firing Behavior ◽  
Vestibular Neurons ◽  
Gaze Saccades ◽  
Stimulation Of

The firing behavior of 51 non-eye movement related central vestibular neurons that were sensitive to passive head rotation in the plane of the horizontal semicircular canal was studied in three squirrel monkeys whose heads were free to move in the horizontal plane. Unit sensitivity to active head movements during spontaneous gaze saccades was compared with sensitivity to passive head rotation. Most units (29/35 tested) were activated at monosynaptic latencies following electrical stimulation of the ipsilateral vestibular nerve. Nine were vestibulo-spinal units that were antidromically activated following electrical stimulation of the ventromedial funiculi of the spinal cord at C1. All of the units were less sensitive to active head movements than to passive whole body rotation. In the majority of cells (37/51, 73%), including all nine identified vestibulo-spinal units, the vestibular signals related to active head movements were canceled. The remaining units ( n = 14, 27%) were sensitive to active head movements, but their responses were attenuated by 20–75%. Most units were nearly as sensitive to passive head-on-trunk rotation as they were to whole body rotation; this suggests that vestibular signals related to active head movements were cancelled primarily by subtraction of a head movement efference copy signal. The sensitivity of most units to passive whole body rotation was unchanged during gaze saccades. A fundamental feature of sensory processing is the ability to distinguish between self-generated and externally induced sensory events. Our observations suggest that the distinction is made at an early stage of processing in the vestibular system.

Human Head-Free Gaze Saccades to Targets Flashed Before Gaze-Pursuit Are Spatially Accurate

1998 ◽  
Vol 80 (5) ◽  
pp. 2785-2789 ◽  
Author(s):  
Troy M. Herter ◽  
Daniel Guitton
Keyword(s):  
Motor System ◽  
Human Subjects ◽  
Human Head ◽  
Horizontal Meridian ◽  
Visual Axis ◽  
Saccade Onset ◽  
On Line ◽  
Saccade Task ◽  
Gaze Position ◽  
Gaze Saccades

Herter, Troy M. and Daniel Guitton. Human head-free gaze saccades to targets flashed before gaze-pursuit are spatially accurate. J. Neurophysiol. 80: 2785–2789, 1998. Previous studies have shown that accurate saccades can be generated, in the dark, that compensate for movements of the visual axis that result from movements of either the eyes alone or the head alone that intervene between target presentation and saccade onset. We have carried out experiments with human subjects to test whether gaze saccades (gaze = eye-in-space = eye-in-head + head-in-space) can be generated that compensate for smooth pursuit movements of gaze that intervene between target onset and gaze-saccade onset. In both head-unrestrained (head-free) and -restrained (head-fixed) conditions, subjects were asked to make gaze shifts, in the dark, to the remembered location of a briefly flashed target. On most trials, during the memory period, the subjects carried out intervening head-free gaze pursuit or head-fixed ocular pursuit along the horizontal meridian. On the remaining (control) trials, subjects did not carry out intervening pursuit movements during the memory period; this was the classical memory-guided saccade task. We found that the subjects accurately compensated for intervening movements of the visual axis in both the head-free and head-fixed conditions. We conclude that the human gaze-motor system is able to monitor on-line changes in gaze position and add them to initial retinal error, to program spatially accurate gaze saccades.

Three-Dimensional Eye-Head Coordination During Gaze Saccades in the Primate

1999 ◽  
Vol 81 (4) ◽  
pp. 1760-1782 ◽  
Author(s):  
J. Douglas Crawford ◽  
Melike Z. Ceylan ◽  
Eliana M. Klier ◽  
Daniel Guitton
Keyword(s):  
Trajectory Optimization ◽  
Control Strategies ◽  
Three Dimensional ◽  
Slow Phase ◽  
Head Orientation ◽  
Eccentric Fixation ◽  
Listing's Law ◽  
Listing’S Law ◽  
Motor Error ◽  
Gaze Saccades

Three-dimensional eye-head coordination during gaze saccades in the primate. The purpose of this investigation was to describe the neural constraints on three-dimensional (3-D) orientations of the eye in space (Es), head in space (Hs), and eye in head (Eh) during visual fixations in the monkey and the control strategies used to implement these constraints during head-free gaze saccades. Dual scleral search coil signals were used to compute 3-D orientation quaternions, two-dimensional (2-D) direction vectors, and 3-D angular velocity vectors for both the eye and head in three monkeys during the following visual tasks: radial to/from center, repetitive horizontal, nonrepetitive oblique, random (wide 2-D range), and random with pin-hole goggles. Although 2-D gaze direction (of Es) was controlled more tightly than the contributing 2-D Hs and Eh components, the torsional standard deviation of Es was greater (mean 3.55°) than Hs (3.10°), which in turn was greater than Eh (1.87°) during random fixations. Thus the 3-D Es range appeared to be the byproduct of Hs and Eh constraints, resulting in a pseudoplanar Es range that was twisted (in orthogonal coordinates) like the zero torsion range of Fick coordinates. The Hs fixation range was similarly Fick-like, whereas the Eh fixation range was quasiplanar. The latter Eh range was maintained through exquisite saccade/slow phase coordination, i.e., during each head movement, multiple anticipatory saccades drove the eye torsionally out of the planar range such that subsequent slow phases drove the eye back toward the fixation range. The Fick-like Hs constraint was maintained by the following strategies: first, during purely vertical/horizontal movements, the head rotated about constantly oriented axes that closely resembled physical Fick gimbals, i.e., about head-fixed horizontal axes and space-fixed vertical axes, respectively (although in 1 animal, the latter constraint was relaxed during repetitive horizontal movements, allowing for trajectory optimization). However, during large oblique movements, head orientation made transient but dramatic departures from the zero-torsion Fick surface, taking the shortest path between two torsionally eccentric fixation points on the surface. Moreover, in the pin-hole goggle task, the head-orientation range flattened significantly, suggesting a task-dependent default strategy similar to Listing’s law. These and previous observations suggest two quasi-independent brain stem circuits: an oculomotor 2-D to 3-D transformation that coordinates anticipatory saccades with slow phases to uphold Listing’s law, and a flexible “Fick operator” that selects head motor error; both nested within a dynamic gaze feedback loop.

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