Statocyst-Induced Eye Movements in the Crab Scylla Serrata

1973 ◽  
Vol 59 (1) ◽  
pp. 17-38
Author(s):  
D. C. SANDEMAN ◽  
A. OKAJIMA
Keyword(s):  
Eye Movement ◽  
Contralateral Side ◽  
Scylla Serrata ◽  
Slow Phase ◽  
Fast Phase ◽  
Preferred Direction ◽  
Sensory Axons ◽  
Proprioceptive Input ◽  
Motor Neurones ◽  
The Brain

1. The sensory axons of the thread hair receptors, free hook hair receptors and most receptors of the statolith area of the crab statocyst all project to the same dorsolateral part of the brain. Large sensory receptors which innervate some hairs surrounding the statolith project to a more ventral site, and send some branches across to the contralateral side of the brain. 2. The central projections of oculomotor neurones have a characteristically open branch pattern and their dendritic field corresponds closely with that of the thread hairs. There are no branches extending to the contralateral side of the brain. 3. Intracellular responses from the motor neurones of horizontal eye-movement muscles during nystagmus show that they are probably directly inhibited during a fast-phase movement of the eye opposite to the direction in which they act. During a slow-phase eye movement opposite to their preferred direction the input to the motor neurones is diminished pre-synaptically. 4. Sets of antagonist motor neurones maintain a fairly rigid relationship to one another so that an increase in activity of one set leads to a decrease in the antagonists. Neither this, nor the onset of the fast phase of nystagmus, is governed by proprioceptive input or by the frequency of discharge of the motor neurones themselves.

Neuronal activity in prepositus nucleus correlated with eye movement in the alert cat

1982 ◽  
Vol 47 (2) ◽  
pp. 329-352 ◽  
Author(s):  
J. Lopez-Barneo ◽  
C. Darlot ◽  
A. Berthoz ◽  
R. Baker
Keyword(s):  
Eye Movements ◽  
Eye Movement ◽  
Optokinetic Nystagmus ◽  
Discharge Rate ◽  
Neuronal Response ◽  
Firing Frequency ◽  
Slow Phase ◽  
Eye Position ◽  
Spatial Integration ◽  
Preferred Direction

1. In nine alert chronically prepared cats the activity of 177 neurons was recorded in the prepositus nucleus during either spontaneous eye movement or that induced by natural vestibular and optokinetic stimulation. 2. In 116 cells, eye position and/or eye velocity was precisely and unequivocally encoded whatever the origin of the eye movement. These cells were separated into different populations according to the eye movement variable encoded and the directionality of the neuronal response. The firing rates of the remaining 61 cells were loosely related to eye movements because a variety of discharge patterns were observed during identical eye movements. In the latter case, some other unmeasured variable (e.g., neck or visual) was suggested to be encoded in the firing frequency. 3. Discharge rate changed before the eyes began to move and reached a new steady level during fixation following a saccade into a particular direction of the orbit. The ondirection was horizontal for 59% of the neurons, vertical for 17%, and oblique for 24%. 4. Regardless of their preferred direction, the discharge rate in 19% of the neurons was closely proportional to eye position. The range in sensitivity was from 1.1 to 7.5 spikes X s-1/deg. Weak velocity responses were occasionally observed during the slow phase of vestibular and optokinetic nystagmus including during saccades. This class of neurons exhibited a very regular interspike interval for a given position of fixation. Since mainly eye position was encoded, these cells were called position neurons. 5. Other prepositus neurons showed both position and velocity sensitivity during saccades and fixation. Their firing rate encoded eye position over the same range as above and also coded velocity during the slow phase of vestibular and optokinetic nystagmus. Depending on the weighting between the position and velocity proportionality constants, these neurons were classified into position-velocity (48%) or velocity-position (33%) groups. 6. The distribution of the above responses led to the conclusion that the prepositus nucleus plays a role in vertical and horizontal spatial integration. The predominance of horizontal activity suggested that the nucleus may be a significant site underlying genesis of horizontal eye position.

scholarly journals Fixation eye movement abnormalities and stereopsis recovery following strabismus repair

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Talora L. Martin ◽  
Jordan Murray ◽  
Kiran Garg ◽  
Charles Gallagher ◽  
Aasef G. Shaikh ◽  
...  
Keyword(s):  
Eye Movements ◽  
Eye Movement ◽  
Functional Improvement ◽  
Slow Phase ◽  
Fixational Eye Movements ◽  
Movement Characteristics ◽  
Adaptive Mechanisms ◽  
Before And After ◽  
Gaze Holding ◽  
Fixational Saccades

AbstractWe evaluated the effects of strabismus repair on fixational eye movements (FEMs) and stereopsis recovery in patients with fusion maldevelopment nystagmus (FMN) and patients without nystagmus. Twenty-one patients with strabismus, twelve with FMN and nine without nystagmus, were tested before and after strabismus repair. Eye-movements were recorded during a gaze-holding task under monocular viewing conditions. Fast (fixational saccades and quick phases of nystagmus) and slow (inter-saccadic drifts and slow phases of nystagmus) FEMs and bivariate contour ellipse area (BCEA) were analyzed in the viewing and non-viewing eye. Strabismus repair improved the angle of strabismus in subjects with and without FMN, however patients without nystagmus were more likely to have improvement in stereoacuity. The fixational saccade amplitudes and intersaccadic drift velocities in both eyes decreased after strabismus repair in subjects without nystagmus. The slow phase velocities were higher in patients with FMN compared to inter-saccadic drifts in patients without nystagmus. There was no change in the BCEA after surgery in either group. In patients without nystagmus, the improvement of the binocular function (stereopsis), as well as decreased fixational saccade amplitude and intersaccadic drift velocity, could be due, at least partially, to central adaptive mechanisms rendered possible by surgical realignment of the eyes. The absence of improvement in patients with FMN post strabismus repair likely suggests the lack of such adaptive mechanisms in patients with early onset infantile strabismus. Assessment of fixation eye movement characteristics can be a useful tool to predict functional improvement post strabismus repair.

scholarly journals A Fast and Effective System for Analysis of Optokinetic Waveforms with a Low-Cost Eye Tracking Device

Healthcare ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 10
Author(s):  
Chong-Bin Tsai ◽  
Wei-Yu Hung ◽  
Wei-Yen Hsu
Keyword(s):  
Eye Movements ◽  
Eye Tracking ◽  
Eye Movement ◽  
Low Cost ◽  
Saccadic Eye Movements ◽  
Slow Phase ◽  
Eye Tracker ◽  
Effective System ◽  
Tracking Device ◽  
Traditional Approaches

Optokinetic nystagmus (OKN) is an involuntary eye movement induced by motion of a large proportion of the visual field. It consists of a “slow phase (SP)” with eye movements in the same direction as the movement of the pattern and a “fast phase (FP)” with saccadic eye movements in the opposite direction. Study of OKN can reveal valuable information in ophthalmology, neurology and psychology. However, the current commercially available high-resolution and research-grade eye tracker is usually expensive. Methods & Results: We developed a novel fast and effective system combined with a low-cost eye tracking device to accurately quantitatively measure OKN eye movement. Conclusions: The experimental results indicate that the proposed method achieves fast and promising results in comparisons with several traditional approaches.

scholarly journals The path from trigeminal asymmetry to cognitive impairment: a behavioral and molecular study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Maria Paola Tramonti Fantozzi ◽  
Giulia Lazzarini ◽  
Vincenzo De Cicco ◽  
Angela Briganti ◽  
Serena Argento ◽  
...  
Keyword(s):  
Pupil Size ◽  
Muscle Spindles ◽  
Molecular Study ◽  
Contralateral Side ◽  
Acute Effects ◽  
Adult Rats ◽  
Afferent Inputs ◽  
Acute And Chronic Effects ◽  
The Brain ◽  
Mandibular Branch

AbstractTrigeminal input exerts acute and chronic effects on the brain, modulating cognitive functions. Here, new data from humans and animals suggest that these effects are caused by trigeminal influences on the Locus Coeruleus (LC). In humans subjects clenching with masseter asymmetric activity, occlusal correction improved cognition, alongside with reductions in pupil size and anisocoria, proxies of LC activity and asymmetry, respectively. Notably, reductions in pupil size at rest on the hypertonic side predicted cognitive improvements. In adult rats, a distal unilateral section of the trigeminal mandibular branch reduced, on the contralateral side, the expression of c-Fos (brainstem) and BDNF (brainstem, hippocampus, frontal cortex). This counterintuitive finding can be explained by the following model: teeth contact perception loss on the lesioned side results in an increased occlusal effort, which enhances afferent inputs from muscle spindles and posterior periodontal receptors, spared by the distal lesion. Such effort leads to a reduced engagement of the intact side, with a corresponding reduction in the afferent inputs to the LC and in c-Fos and BDNF gene expression. In conclusion, acute effects of malocclusion on performance seem mediated by the LC, which could also contribute to the chronic trophic dysfunction induced by loss of trigeminal input.

Possible cues driving context-specific adaptation of optocollic reflex in pigeons (Columba livia)

2012 ◽  
Vol 107 (2) ◽  
pp. 704-717 ◽  
Author(s):  
Henri Gioanni ◽  
Pierre-Paul Vidal
Keyword(s):  
Columba Livia ◽  
Motor Command ◽  
Slow Phase ◽  
Gaze Stabilization ◽  
Specific Adaptation ◽  
Body Vibration ◽  
Fast Phase ◽  
Context Specific ◽  
Context Cues

Context-specific adaptation (Shelhamer M, Clendaniel R. Neurosci Lett 332: 200–204, 2002) explains that reflexive responses can be maintained with different “calibrations” for different situations (contexts). Which context cues are crucial and how they combine to evoke context-specific adaptation is not fully understood. Gaze stabilization in birds is a nice model with which to tackle that question. Previous data showed that when pigeons ( Columba livia) were hung in a harness and subjected to a frontal airstream provoking a flying posture (“flying condition”), the working range of the optokinetic head response [optocollic reflex (OCR)] extended toward higher velocities compared with the “resting condition.” The present study was aimed at identifying which context cues are instrumental in recalibrating the OCR. We investigated that question by using vibrating stimuli delivered during the OCR provoked by rotating the visual surroundings at different velocities. The OCR gain increase and the boost of the fast phase velocity observed during the “flying condition” were mimicked by body vibration. On the other hand, the newly emerged relationship between the fast-phase and slow-phase velocities in the “flying condition” was mimicked by head vibration. Spinal cord lesion at the lumbosacral level decreased the effects of body vibration, whereas lesions of the lumbosacral apparatus had no effect. Our data suggest a major role of muscular proprioception in the context-specific adaptation of the stabilizing behavior, while the vestibular system could contribute to the context-specific adaptation of the orienting behavior. Participation of an efferent copy of the motor command driving the flight cannot be excluded.

Fast-phase transvascular fluid flux and the Fahraeus effect

1987 ◽  
Vol 62 (4) ◽  
pp. 1513-1520 ◽  
Author(s):  
W. N. Richardson ◽  
D. Bilan ◽  
M. Hoppensack ◽  
L. Oppenheimer
Keyword(s):  
Mechanical Properties ◽  
Slow Rate ◽  
Time Course ◽  
Rate Of Change ◽  
Distributed Model ◽  
Slow Phase ◽  
Fluid Flux ◽  
Fast Phase ◽  
Constant Rate ◽  
Fahraeus Effect

Transvascular fluid flux was induced in six isolated blood-perfused canine lobes by increasing and decreasing hydrostatic inflow pressure (Pi). Fluid flux was followed against the change in concentration of an impermeable tracer (Blue Dextran) measured directly with a colorimetric device. The time course of fluid flux was biphasic with an initial fast transient followed by a slow phase. Hematocrit changes unrelated to fluid flux occurred due to the Fahraeus effect, and their contribution to the total color signal was subtracted to determine the rate of fast fluid flux (Qf). Qf was related to Pi to derive fast-phase conductance (Kf). Slow-phase Kf was calculated from the constant rate of change of lobe weight. For a mean change in Pi of 7 cmH2O, 40% of the color signal was due to fluid flux. Fast- and slow-phase Kf's were 0.86 +/- 0.15 and 0.27 +/- 0.05 ml X min-1. cmH2O–1 X 100 g dry wt-1. The fast-phase Kf is smaller than that reported for plasma-perfused lobes. Possible explanations discussed are the nature of the perfusate, the mechanical properties of the interstitium, and the slow rate of rise of the driving pressure at the filtration site on the basis of a distributed model of pulmonary vascular compliance.

Quantitative Analysis of Abducens Neuron Discharge Dynamics During Saccadic and Slow Eye Movements

1999 ◽  
Vol 82 (5) ◽  
pp. 2612-2632 ◽  
Author(s):  
Pierre A. Sylvestre ◽  
Kathleen E. Cullen
Keyword(s):  
Eye Movements ◽  
Firing Rate ◽  
Eye Movement ◽  
Neuronal Activity ◽  
Smooth Pursuit ◽  
Slow Phase ◽  
Vestibular Nystagmus ◽  
Firing Rates ◽  
Rapid Eye Movements ◽  
Eye Velocity

The mechanics of the eyeball and its surrounding tissues, which together form the oculomotor plant, have been shown to be the same for smooth pursuit and saccadic eye movements. Hence it was postulated that similar signals would be carried by motoneurons during slow and rapid eye movements. In the present study, we directly addressed this proposal by determining which eye movement–based models best describe the discharge dynamics of primate abducens neurons during a variety of eye movement behaviors. We first characterized abducens neuron spike trains, as has been classically done, during fixation and sinusoidal smooth pursuit. We then systematically analyzed the discharge dynamics of abducens neurons during and following saccades, during step-ramp pursuit and during high velocity slow-phase vestibular nystagmus. We found that the commonly utilized first-order description of abducens neuron firing rates (FR = b + kE + rE˙, where FR is firing rate, E and E˙ are eye position and velocity, respectively, and b, k, and r are constants) provided an adequate model of neuronal activity during saccades, smooth pursuit, and slow phase vestibular nystagmus. However, the use of a second-order model, which included an exponentially decaying term or “slide” (FR = b + kE + rE˙ + uË − c[Formula: see text]), notably improved our ability to describe neuronal activity when the eye was moving and also enabled us to model abducens neuron discharges during the postsaccadic interval. We also found that, for a given model, a single set of parameters could not be used to describe neuronal firing rates during both slow and rapid eye movements. Specifically, the eye velocity and position coefficients ( r and k in the above models, respectively) consistently decreased as a function of the mean (and peak) eye velocity that was generated. In contrast, the bias ( b, firing rate when looking straight ahead) invariably increased with eye velocity. Although these trends are likely to reflect, in part, nonlinearities that are intrinsic to the extraocular muscles, we propose that these results can also be explained by considering the time-varying resistance to movement that is generated by the antagonist muscle. We conclude that to create realistic and meaningful models of the neural control of horizontal eye movements, it is essential to consider the activation of the antagonist, as well as agonist motoneuron pools.

scholarly journals Mechanism of retraction of the trailing edge during fibroblast movement.

1981 ◽  
Vol 90 (1) ◽  
pp. 187-200 ◽  
Author(s):  
W T Chen
Keyword(s):  
Slow Component ◽  
Fast Component ◽  
Slow Phase ◽  
Main Body ◽  
Elastic Recoil ◽  
Forward Movement ◽  
Trailing Edge ◽  
Fast Phase ◽  
Focal Contacts

Retraction of the taut, trailing portion of a moving chick heart fibroblast in vitro is an abrupt dynamic process. Upon retraction, the fibroblast tail always ruptures, leaving a small amount of itself attached to the substratum by focal contacts. Time-lapse cinemicrography shows that retraction produces a sudden, massive movement of both surface and cytoplasmic material toward a cluster of focal contacts near the main body of the cell. The appearance of folds on the upper cell surface at this time and the absence of endocytotic vesicles are consistent with this forward movement. Retraction of the trailing edge, either occurring naturally or produced artificially with a microneedle, consists of an initial fast component followed and overlapped by a slow component. Upon artificial detachment in the presence of iodoacetate, dinitrophenol, and sodium fluoride, and at 4 degrees C, the slow component is strongly inhibited and the fast one only slightly inhibited. Moreover of the bundles of microfilaments oriented parallel to the long axis of the tail seen in TEM. Most of the birefringence is lost during the fast phase and the rest during the slow phase of retraction. Concurrently, the bundles of microfilaments disappear during the fast phase of retraction and are replaced by a microfilament meshwork. All of these results are consistent with the hypothesis that the initial fast component of retraction is a passive elastic recoil, associated with the oriented bundles of microfilaments, and that the slow component of retraction is an active contraction, associated with a meshwork of microfilaments.

scholarly journals The assembly of microtubule protein in vitro. The kinetic role in microtubule elongation of oligomeric fragments containing microtubule-associated proteins

1985 ◽  
Vol 227 (2) ◽  
pp. 439-455 ◽  
Author(s):  
P M Bayley ◽  
F M M Butler ◽  
D C Clark ◽  
E J Manser ◽  
S R Martin
Keyword(s):  
Self Assembly ◽  
Protein Concentration ◽  
Wavelength Dependence ◽  
Electrophoretic Analysis ◽  
Slow Phase ◽  
Condensation Polymerization ◽  
Fast Phase ◽  
Microtubule Protein ◽  
Kinetics Of

The kinetics of assembly were studied for bovine and pig microtubule protein in vitro over a range of conditions of pH, temperature, nucleotide and protein concentration. The kinetics are in general biphasic with two major processes of similar amplitude but separated in rate by one order of magnitude. Rates and amplitudes are complex functions of solution conditions. The rates of the fast phase and the slow phase attain limiting values as a function of increasing protein concentration, and are more stringently limited at pH 6.5 than pH 6.95. Such behaviour indicates that mechanisms other than the condensation polymerization of tubulin dimer become rate-limiting at higher protein concentration. The constancy of the wavelength-dependence of light-scattering and ultrastructural criteria indicate that microtubules of normal morphology are formed in both phases of the assembly process. Electrophoretic analysis of assembling microtubule protein shows that MAP- (microtubule-associated-protein-)rich microtubules are formed during the fast phase. The rate of dissociation of oligomeric species on dilution of microtubule protein closely parallels the fast-phase rate in magnitude and temperature-dependence. We propose that the rate of this process constitutes an upper limit to the rate of the fast phase of assembly. The kinetics of redistribution of MAPs from MAP-rich microtubules may be a factor limiting the slow-phase rate. A working model is derived for the self-assembly of microtubule protein incorporating the dissociation and redistribution mechanisms that impose upper limits to the rates of assembly attainable by bimolecular addition reactions. Key roles are assigned to MAP-containing fragments in both phases of microtubule elongation. Variations in kinetic behaviour with solution conditions are inferred to derive from the nature and properties of fragments formed from oligomeric species after the rapid temperature jump. The model accounts for the limiting rate behaviour and indicates experimental criteria to be applied in evaluating the relative contributions of alternative pathways.

Vestibular Signals in Self-Orientation and Eye Movement Control

Physiology ◽  
2001 ◽  
Vol 16 (5) ◽  
pp. 234-238 ◽  
Author(s):  
Bernhard J. M. Hess
Keyword(s):  
Signal Processing ◽  
Eye Movement ◽  
Vestibular System ◽  
Retinal Image ◽  
Internal Model ◽  
Movement Control ◽  
Head Position ◽  
Head Motion ◽  
Afferent Information ◽  
The Brain

The central vestibular system receives afferent information about head position as well as rotation and translation. This information is used to prevent blurring of the retinal image but also to control self-orientation and motion in space. Vestibular signal processing in the brain stem appears to be linked to an internal model of head motion in space.

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