SEARCH · Search PubMed

Results for “Eye Movements”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 901 records · Page 50Linked to original sources

PubMed1978

Eye movements of monkeys during learning-set formation.

Eye movements of stump-tailed monkeys were measured during learning of a long series of two-choice pattern discrimination problems. The amount of scanning per trial (shifts in visual fixation from one pattern to the other) and the duration of individual fixations on the patterns increased during the course of learning-set formation and (except for the amount of scanning by some animals) remained high during the prolonged training following learning-set formation. Some of the changes in eye movements were different from those seen during the learning of single discrimination problems, a difference that possibly reflects cognitive processes specific to the learning-set task.

Animals↗

PubMed1990

Source of the eye-movement signal reaching real-motion cells.

The stability of visual perception despite eye movements suggests the existence in the visual system of neurons able to recognize whether the movement of a retinal image is due to the actual movement of an object or is self-induced by the ocular movement. We found neurons of this type in several areas of the monkey visual cortex and named them "real-motion" cells. Extracellular recordings were carried out from single neurons of the cortical prestriate area V3A of two awake macaque monkeys. Eighty-seven neurons were studied by comparing their responses during stimulus movement across the stationary receptive field, and receptive-field movement across the stationary stimulus. This visual stimulation was presented against a uniform visual background, in darkness or against a textured background. Neurons which were not real-motion in light (45/87) maintained their behaviour in darkness, while about 40% of real-motion cells lost this behaviour in darkness. Both real-motion and non real-motion cells maintained the same behaviour when tested against a uniform or textured visual background but often, texture increased the difference in the response that real-motion cells showed between stimulus and eye movement. These data suggest that the eye-movement signal which reaches real-motion cells and is responsible for their behaviour may be either retinal or extraretinal in nature. This double innervation is in good agreement with perceptual phenomena related to the detection of movement in the visual field.

Animals↗

PubMed1993

Quantitative evaluation of saccadic and smooth pursuit eye movements. Is it reliable?

PURPOSE: The authors evaluated the reliability of the coefficients of the (1) amplitude/duration and (2) amplitude/peak velocity relationships of the mean precision values and the mean latency values (saccadic eye movements) and the coefficients of the target velocity/gain relationship (smooth pursuit eye movements). They computed test-retest maximum variability limits for these parameters. METHODS: After a 1-week interval, saccadic and smooth pursuit eye movements were recorded twice from 20 healthy subjects; 12 of these subjects underwent a third recording session. The estimate of the intraclass coefficient of reliability, R, was adopted to evaluate the reliability of eye movement quantitative analysis. RESULTS: The data demonstrated that the reliability was fairly good for the amplitude/peak velocity relationship, was good for the precision, and was excellent for the amplitude/duration, the target velocity/gain relationships, and the latency. CONCLUSIONS: Quantitative analysis of both saccadic and smooth pursuit eye movements is reliable. One statistic used to estimate reliability, ie, the within-subjects mean square value, also enables the determination of test-retest normal variability values for both the variances and the differences of measurements.

Adult↗

PubMed1992

Relationship between conjugate lateral eye movements and alexithymia.

The relationship between conjugate lateral eye movements (CLEMs) and alexithymia was investigated in a group of 60 (23 male and 37 female) right-handed university students. Subjects completed the Toronto Alexithymia Scale (TAS), the Schalling-Sifneos Personality Scale, and the Basic Personality Inventory, which measures 12 basic dimensions of personality and psychopathology, CLEMs were recorded while subjects were asked 20 general knowledge questions that have no tendency to elicit eye movements predominantly in one direction. A series of gender by CLEM preference (left vs. right mover) ANOVAs were conducted with the various measures. There was a significant relationship between right CLEM preference and higher scores on the TAS, but no relationships between CLEMs and any of the other measures. These results suggest that alexithymia is associated with left cerebral lateralization, and support the hypothesis that alexithymic characteristics reflect a variation in brain organization.

Adult↗

PubMed1991

Eye movements elicited by electrical stimulation of area PG in the monkey.

1. Eye positions of monkeys were tracked while low-current electrical stimulation was delivered to area PG of the posterior parietal cortex. Stimulation was delivered while monkeys were in darkness, while they were in a dimly illuminated room, or while they actively fixated on small lamps to receive a liquid reward. 2. Resulting eye movements fell into one of three categories, depending roughly on the area stimulated. Stimulation of caudal regions generally resulted in saccades that were of approximately equivalent amplitudes and directions. When more rostral areas were stimulated, saccades were generally produced that directed the eyes toward roughly the same position in the head. Distributed throughout all regions were sites for which elicited saccades did not fall clearly into either of these coordinate bases. Stimulation of lateral areas produced low-velocity eye movements that were directed ipsilaterally from the stimulated hemisphere. 3. Stimulation made while monkeys fixated on target lamps produced saccades with more variability and less amplitude than those produced while monkeys were in darkness. Low-velocity eye movements could only be elicited while monkeys were in darkness. 4. Craniocentric saccades typically brought the eyes to within a 10-20 degrees area, and saccades could not be produced when the initial eye position was near this area. Craniocentric saccades were always greater than 5 degrees in amplitude. 5. It is concluded that area PG is organized into at least two zones that differ in the way by which they code saccades. A caudal region codes saccades in a way similar to that found in the frontal cortex and superior colliculus of primates. A rostral region codes saccades in a craniocentric manner, although it is restricted only to gross redirection of gaze without the accuracy monkeys are capable of using in directing their eyes.

Animals↗

PubMed1995

Eye movement desensitization of public-speaking anxiety: a partial dismantling.

Forty college students suffering from public speaking anxiety and having experienced a specific traumatic speech-related event were exposed to either a standard EMD protocol with eye movements; a moving audio stimulus in place of the eye movements; a protocol with eyes resting on the hands in place of the eye movement, or a no-treatment control condition. The results revealed that EMD is comparable in limited effectiveness to the other procedures and that the eye movements are not a crucial component of the treatment with this population.

Adolescent↗

PubMed1998

Eye movements, prematurity and developmental co-ordination disorder.

Horizontal pursuit eye movements were investigated in two separate groups of children: One group exhibited developmental co-ordination disorder (n = 8) whilst another group of children were born prematurely (n = 8). Both studies found a reduced gain in pursuit eye movements when the respective populations were compared with control groups (n = 32). A difference was also found in the ability of some children to temporally synchronize their tracking response to the stimulus, which was indicative of poor predictive control rather than lags in the control system. We suggest that horizontal eye movements may be a sensitive indicator of more general motor deficits during childhood development.

Adult↗

PubMed1981

The composition of central programs subserving horizontal eye movements in man.

A hypothesis is presented which describes, in biomechanical terms, the central programs underlying horizontal eye movements in man. It is suggested that eye movements are produced by means of programmed shifts of the so-called invariant muscle characteristics (static force vs angle phi of gaze). These shifts lead to a change of the equilibrium point resulting from the interaction of agonist and antagonist muscles and, as a consequence, to movement and the attainment of a new position of gaze. A reciprocal or a coactivation command to agonist and antagonist muscles occurs when their characteristics shift with respect to the coordinate phi in the same or opposite directions, respectively. It is proposed that during pursuit and saccadic eye movements a superposition of the both central commands occurs. During a saccade, the reciprocal command develops evenly up to a certain level. The initial and final levels of the reciprocal command dictate the respective position of gaze and therefore the size of the saccade. The coactivation command develops to a maximum level and is slowly switched off when the new position of gaze has been achieved. The magnitude of the coactivation command seems to be not connected with an absolute position of gaze. It provides probably a stability of the movement and, in particular, prevents overshoot and oscillation during the saccade. The same timing of these commands occurs during pursuit movements, but the magnitude of the coactivation command and the rates of the development of the both commands are less in this case and correlate with the velocity of the movement. This hypothesis enables the tension changes in the muscle during saccadic and pursuit movements to be simulated in qualitative accordance with unique experimental data obtained by Collins et al. (1975). The functional significance of superposition of these motor commands and similarity in the efferent organization of eye and limb movements are discussed. Analysis of limb movements in man and animals has allowed one to formulate some concepts concerning the motor control. For instance, it has been suggested and experimentally confirmed that central commands are adequately expressed in terms of shifts of muscle static length - force characteristics and specify an equilibrium point resulting from the interaction of agonist and antagonist muscles (Asatryan and Feldman, 1965; Felman, 1966a, 1974, 1979, 1980a, b; Bizzi et al., 1976; Kelso, 1977; Polit and Bizzi, 1978, 1979; Houk, 1979; Kelso and Holt, 1980). Experimental observation have also shown that two central commands, i.e. reciprocal and unidirectional activation of agonist and antagonist muscles are usually combined by the nervous system in a proper manner depending on the motor task (Feldman, 1979, 1980a, b). The present, theoretical report is designed to show that these concepts are consistent with available experimental data concerning oculomotor control.

Eye Movements↗

PubMed1989

Eye movements induced by microinjection of GABA agonist in the rat substantia nigra pars reticulata.

Injection of muscimol (GABA agonist) in the substantia nigra pars reticulata (SNr) of the alert rat induced a continual repetition of fast eye movements to the contralateral side, each of which was followed by a slow returning movement. The fast eye movements were similar to spontaneous saccades. Larger saccades were accompanied by contralateral neck muscle activity. We suggest that the SNr plays an important role in control of eye movements in the rat.

Animals↗

PubMed2004

EEG activity related to preparation and suppression of eye movements in three-dimensional space.

Eight normal subjects made visually guided eye movements to four LED targets placed at two different distances (20 and 70 cm) and on either side (+/-10 degrees ) at 70 cm. Four types of eye movements were elicited: pure saccades, convergence, divergence, and combined (divergent saccades). EEG activity was recorded from 62 electrodes and was aligned to stimulus onset. A negativity peaked after 140 ms and was modulated according to the location of the stimulus in space and the type of movement prepared, mainly in central and posterior cortex. For saccade targets, we confirmed a stimulus-related negativity in the posterior and central cortical area, contralateral to target direction. For convergence and divergence targets, this negativity was bilaterally distributed; convergence targets activated a rather extended cortical network in the central and posterior area, while divergence targets activated a more confined posterior area, spreading ventrally from the occipital cortex. Cortical activity for combined targets was lateralised contralaterally to stimulus direction but its topography resembled more closely that after the divergence stimulus. When observers suppressed the relevant eye movement to the stimulus, EEG activity was enhanced on the right hemisphere, showing the more pronounced effect on the right occipital-temporal and central-parietal electrode sites.

Adult↗

PubMed1982

Use of eye movement auditory biofeedback in the control of nystagmus.

Eye movement auditory biofeedback was used in weekly training sessions to control nystagmus in five adult patients. Within the 1st hr of training, all patients were able to reduce nystagmus. Average maximum group reduction of nystagmus amplitude, peak slow-phase velocity, and frequency achieved during training with auditory biofeedback was 82, 86, and 34%, respectively. At periodic intervals during training, audio information was withheld and patients were able to maintain reduced nystagmus for several minutes. In addition, patients were able to reduce nystagmus upon command without audio cues but with conscious effort while engaging in conversation and other tasks with the experimenters. Visual acuity improvement with conscious patient effort to control nystagmus but without auditory biofeedback averaged 10% Snell-Sterling. One of two patients who returned for post-training reevaluation was able to reduce his nystagmus quickly without auditory biofeedback to 50% of the pretraining level, and both patients were able with the aid of auditory cues to reduce their nystagmus rapidly to the level achieved during training. In addition to the improvement in vision, cosmetic and psychological benefits accrued. Eye movement auditory biofeedback should be considered in the treatment of nystagmus, either alone or in conjunction with orthoptic and/or surgical procedures.

Acoustic Stimulation↗

PubMed1997

[Effects of melatonin and diazepam on the eye movement and postural muscle tone in decerebrate cats].

We studied the effects of melatonin and diazepam on eye movement and muscle activity in decerebrate cats, and results were compared with those obtained from carbachol injection into the pontine reticular formation which was supposed to be a model of REM sleep. In precollicular postmammillary decerebrate cats, the horizontal eye movement and the activity of bilateral triceps surae muscles were recorded under three conditions: (1) microinjection of carbachol into the rostral pontine reticular formation; (2) intravenous administration melatonin; and (3) diazepam. Both rapid eye movement and reduction of muscle activity were induced by carbachol injection, while only reduction of muscle activity was induced by diazepam administration. Neither rapid eye movement nor reduction of muscle activity was induced by melatonin administration in this animal preparation. From these results, we speculated that the inhibitory effect of diazepam on muscle tonus was not manifested through activation of the brainstem REM generating system. It is known that the melatonin receptors are located in several sites of central nervous system, such as suprachiasmatic nucleus, and not in the brainstem and spinal cord. The present results of melatonin administration may support this fact in view of behavioral aspects.

Animals↗

PubMed1999

Three-dimensional organization of vestibular-related eye movements to off-vertical axis rotation and linear translation in pigeons.

During linear accelerations, compensatory reflexes should continually occur in order to maintain objects of visual interest as stable images on the retina. In the present study, the three-dimensional organization of the vestibulo-ocular reflex in pigeons was quantitatively examined during linear accelerations produced by constant velocity off-vertical axis yaw rotations and translational motion in darkness. With off-vertical axis rotations, sinusoidally modulated eye-position and velocity responses were observed in all three components, with the vertical and torsional eye movements predominating the response. Peak torsional and vertical eye positions occurred when the head was oriented with the lateral visual axis of the right eye directed orthogonal to or aligned with the gravity vector, respectively. No steady-state horizontal nystagmus was obtained with any of the rotational velocities (8-58 degrees /s) tested. During translational motion, delivered along or perpendicular to the lateral visual axis, vertical and torsional eye movements were elicited. No significant horizontal eye movements were observed during lateral translation at frequencies up to 3 Hz. These responses suggest that, in pigeons, all linear accelerations generate eye movements that are compensatory to the direction of actual or perceived tilt of the head relative to gravity. In contrast, no translational horizontal eye movements, which are known to be compensatory to lateral translational motion in primates, were observed under the present experimental conditions.

Animals↗

PubMed2004

Involvement of the optic tectum and mesencephalic reticular formation in the generation of saccadic eye movements in goldfish.

The circuitry and physiological properties underlying saccadic eye movement generation have been studied mainly in monkeys and cats. By contrast, current knowledge in nonmammalian species is rather scarce. We review here some of our recent findings about the involvement of the optic tectum and mesencephalic reticular formation in the generation of saccades in goldfish. Electrical microstimulation of the optic tectum evokes contraversive saccadic eye movements. In goldfish, as in mammals, the amplitude and direction of saccades are encoded in a spatial topographical map. In addition, there are some areas that have evolved, such as the extreme anteromedial tectal zone, whose activation yields eye convergence. Injections of the bidirectional tracer biotin dextran amine within functionally identified sites of the tectum provide reciprocal, site-dependent connectivity with different downstream structures. Of these structures, the major tectofugal target is the mesencephalic reticular formation. In goldfish, as in mammals, the mesencephalic reticular formation and optic tectum establish reciprocal connections at regional and neuronal levels which support the presence of feedback circuits. Electrical microstimulation demonstrates that the mesencephalic reticular formation can be functionally parceled-the rostral part is linked to vertical saccades, while the caudal part is related with horizontal ones. Finally, these zones are also differently connected to the optic tectum. From these data, we conclude that the involvement of the optic tectum and mesencephalic reticular formation in eye movement generation in goldfish is similar to that reported in cats and monkeys.

Animals↗

PubMed1994

Responses during eye movements of brain stem neurons that receive monosynaptic inhibition from the flocculus and ventral paraflocculus in monkeys.

1. We have identified a group of brain stem cells called "flocculus target neurons" (or FTNs) because they are inhibited at monosynaptic latencies by stimulation of the flocculus and the ventral paraflocculus with single electrical pulses. We report the responses of FTNs, as well as those of other brain stem cells, during horizontal eye movements with the head stationary and during natural vestibular stimulation in monkeys. 2. FTNs discharged primarily in relation to eye movements. The majority (71%) showed increased firing for eye movement away from the side of the recording ("contraversive"), which is consistent with their inhibition by Purkinje cells that show increased firing for eye movement toward the side of recording. However, a significant and surprisingly large percentage (29%) of FTNs showed increased firing for eye movement toward the side of recording ("ipsiversive"). 3. The firing rate of FTNs showed strong modulation during pursuit of sinusoidal target motion with the head stationary and during the compensatory eye movements evoked by fixation of an earth-stationary target with sinusoidal head rotation. In addition, firing rate was related to eye position during steady fixation at different positions. Of the FTNs that showed increased firing for contraversive eye motion during pursuit with the head stationary, most had an infection in the relationship between firing rate and eye position so that the sensitivity to eye position was low for eye positions ipsilateral to straight-ahead gaze and high for eye positions contralateral to straight-ahead gaze. 4. When the monkey canceled the vestibuloocular reflex (VOR) by tracking a target that moved exactly with him during sinusoidal head rotation, the firing rate of FTNs was modulated much less strongly than during pursuit with the head stationary. In the FTNs that showed increased firing for contraversive eye motion during pursuit, firing rate during cancellation of the VOR increased for contraversive head motion during sinusoidal vestibular rotation at 0.4 Hz but was only weakly modulated during rotation at 0.2 Hz. 5. The position-vestibular-pause cells (PVP-cells), previously identified as interneurons in the disynaptic VOR pathways, were not inhibited by stimulation of the flocculus and ventral paraflocculus and had response properties that were different from FTNs. The majority (69%) showed increased firing for contraversive eye motion during pursuit and for ipsiversive head motion during cancellation of the VOR, whereas some (31%) showed the opposite direction preferences under both conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1981

[A comparison between orienting rapid eye movements accompanying active or passive head movement in the cat].

Gaze is shifted by means of eye saccades which, in most instances, are synchronized with head rotations. During eye-head movements performed by cats in the dark, most of the rapid eye movements start after the head has begun to move (mean time lag was 45 msec). This pattern resembles that observed when the cat, as a whole, is suddenly rotated passively and consists of a short lasting vestibularly induced slow phase component followed by a rapid eye movement that takes the eye in the same direction as the head. We have compared the passively and actively induced eye-head movements. The rapid eye movements are similar in both cases in that they terminate at a fixed position ("goal") in the orbit irrespective of the eye's starting position. They differ primarily in the fact that the eccentricity of the "goal" during active head rotations increases much more rapidly with velocity than it does during the passive condition. The results suggest that the rapid eye movement that accompanies an active head movement in the dark is not simply a vestibularly induced quick phase.

Animals↗

PubMed1978

Role of primate flocculus during rapid behavioral modification of vestibuloocular reflex. I. Purkinje cell activity during visually guided horizontal smooth-pursuit eye movements and passive head rotation.

1. Extracellular recordings were obtained from 124 Purkinje cells (P-cells) in the flocculus of alert monkeys. P-cell simple spike-firing rate was analyzed quantitatively during various combinations of smooth-pursuit eye movement and passive head rotation. 2. During sinusoidal smooth eye movements, 80% of the P-cells displayed increased firing rate during ipsilateral and 20% during contralateral eye movement. Over the frequency range 0.3--1.4 Hz, firing-rate modulation was proportional to and in phase with maximum eye velocity. During the steady state of triangle-wave tracking, firing rate increased monotonically as a function of eye velocity. Since firing rate was uncorrelated with retinal-error velocity, one component of P-cell firing rate was related to eye velocity. 3. During the transient phase of triangle-wave tracking, when an instantaneous change in the direction of target movement caused a large retinal-error velocity, 40% of the P-cells were related only to eye velocity. Sixty percent of the P-cells displayed an overshoot or undershoot in firing rate, indicating a relationship to either retinal-error velocity or eye acceleration as well as to eye velocity. 4. During the vestibuloocular reflex (VOR), evoked by head rotation in the dark, P-cell firing rate was only weakly modulated. In contrast, when the monkey suppressed the VOR by fixating a target that rotated with him, P-cell rate was deeply modulated. Since the modulation was proportional to and in phase with maximum head velocity, another component of P-cell firing rate was related to head velocity. 5. Of 36 P-cells tested, 35 displayed firing-rate modulation during both suppression of the VOR and smooth-pursuit eye movement. P-cells that reached peak firing rate during ipsilateral head rotation also reached peak firing rate during ipsilateral smooth eye rotation. Average population sensitivitites to head velocity and eye velocity were equal. In three conditions in which eye and head velocity were elicited simultaneously, P-cell firing rate could be predicted by the linear, vector addition of the separate eye and head velocity components of firing rate. Therefore, the relatively weak modulation of P-cell firing rate during the VOR in the dark can be accounted for by the cancellation of equal but opposite head and eye velocity components. 6. The connections of flocculus P-cells to interneurons in the brain stem VOR pathways have been established in other mammals. In the context of those connections, P-cell firing patterns were appropriate to facilitate the eye movements the monkey was required to make. We conclude that the flocculus is important for sustaining any smooth eye movements that are different from those evoked by head rotation in the dark. The eye velocity component may represent an efference copy signal that sustains ongoing eye velocity during smooth pursuit.

Animals↗

PubMed1977

Eye movements and over rehearsal in wood recall.

Rates of overt rehearsal and eye movement were compared to each other, and were also compared as predictors of immediate and delayed recall, using practiced subjects who studied lists of eight simultaneously presented words. The correlation between number of eye fixations per word and number of rehearsals per word was greater in immediate than in delayed recall. Also, the number of fixations exceeded the number of overt rehearsals, especially under delayed-recall conditions. However, both overt rehearsals and eye movements were slower in delayed recall. The number of overt rehearsals and the number of fixations per word were good predictors of immediate recall, but neither was highly correlated with delayed recall. Engaging in overt rehearsal had the following effects: It slowed down eye movements, seemed to bias the subject toward a serial learning strategy, improved immediate recall, and did not reduce delayed recall. It was concluded that total looking time was the best predictor of long-term retention and that recall performance following overt rehearsal was different from recall performance following silent study.

Attention↗