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 307 records · Page 17Linked to original sources

PubMed2004

Correspondence of presaccadic activity in the monkey primary visual cortex with saccadic eye movements.

We continuously scan the visual world via rapid or saccadic eye movements. Such eye movements are guided by visual information, and thus the oculomotor structures that determine when and where to look need visual information to control the eye movements. To know whether visual areas contain activity that may contribute to the control of eye movements, we recorded neural responses in the visual cortex of monkeys engaged in a delayed figure-ground detection task and analyzed the activity during the period of oculomotor preparation. We show that approximately 100 ms before the onset of visually and memory-guided saccades neural activity in V1 becomes stronger where the strongest presaccadic responses are found at the location of the saccade target. In addition, in memory-guided saccades the strength of presaccadic activity shows a correlation with the onset of the saccade. These findings indicate that the primary visual cortex contains saccade-related responses and participates in visually guided oculomotor behavior.

Animals↗

PubMed1995

Localized and lateralized cerebral glucose metabolism associated with eye movements during REM sleep and wakefulness: a positron emission tomography (PET) study.

In order to study the neural substrate for eye movements during rapid eye movement (REM) sleep, we analyzed the positron emission tomography (18Fluorodeoxyglucose positron emission tomography) scan data obtained from normal subjects. Eye movement data were available on nine subjects studied during nighttime REM sleep and six control subjects studied during waking as they periodically moved their eyes. The number of eye movements during REM sleep was positively correlated with glucose metabolic rate in the areas corresponding to (a) the saccadic eye movement system (frontal eye field and dorsolateral prefrontal cortex, statistically significant only on the right side), (b) the midline attentional system (cingulate and medial frontal cortex, precuneus) and (c) the parietal visual spatial attentional system (bilateral superior parietal lobules, right inferior parietal lobule); and negatively correlated with relative metabolic rate in the left inferior parietal lobule. Positive correlations between waking eye movements and metabolic rate were observed in the same areas except inferior parietal lobule. Our results show that the same cortical areas are involved in eye movements in both REM sleep and wakefulness and suggest that REM sleep eye movements are saccadic scans of targets in the dream scene. Our data also suggest right hemispheric specialization in saccadic eye movement control and reciprocal inhibition in the contralateral homologous area during higher cortical functioning.

Attention↗

PubMed2003

Eye movement baseline oscillation and variability of eye position during foveation in congenital nystagmus.

Despite the inability to maintain steady fixation, congenital nystagmus does not necessarily reduce visual acuity, that can be achieved during the foveation periods. The duration of the foveation period, but also the cycle-to-cycle variability of eye position and velocity during foveations play an important role. A quantitative relationship that relates visual acuity with foveation time and cycle-to-cycle variability of eye position during foveation has been previously proposed. In many infrared-oculographic and electro-oculographic eye position recordings of our database, a sinusoidal-like oscillation of the baseline was observed, on which the nystagmus waveforms lay. This oscillation may contribute to increase cycle-to-cycle variability during foveations. The aim of this work is to extract the baseline oscillation from the recordings and to verify its relationship with eye position variability during foveation. On the basis of the observations, the baseline oscillation was assumed to be sinusoidal, and was estimated (using a least mean square technique) from eye movement signals recorded during fixation intervals, at different gaze positions, from 20 patients affected by congenital nystagmus with low visual acuity. The average baseline oscillation amplitude was 1.31 degrees, while the average frequency was 0.34 Hz. Baseline oscillation amplitude was well correlated (with a coefficient of 0.66) to the standard deviations of eye-position during foveation, which in turn is connected to visual acuity.

Adolescent↗

PubMed1991

Comparison of two nonlinear models for fitting saccadic eye movement data.

Saccadic eye movements are rapid shifts in the direction of gaze which are being studied increasingly for clinical and pharmacological purposes. The evaluation of the relationship between amplitude and peak velocity of these ocular movements (the so-called 'main sequence' plot) is particularly useful for characterising the saccade pattern in individual patients. This relationship is nonlinear and the peak velocity tends to achieve an asymptote for high values of amplitude. Since a standard parametrisation of the main sequence based on specific mathematical models has not yet been achieved, in the present study two simple models based on the Michaelis-Menten equation and on an exponential equation are proposed together with their implementation on a microcomputer. Two microcomputer programs are described which estimate the model parameters from the experimental data of the patients using a weighted nonlinear least-squares fit. The two procedures have been tested and compared in a series of 23 healthy volunteers. The following results (mean +/- S.D.) were obtained: Michaelis-Menten model. Km (degrees) = 31.2 +/- 7.7, Vmax (degrees/s) = 841.0 +/- 165.5, root-mean-squared error(%) = 6.0 +/- 1.6; exponential model. K (degrees) = 23.4 +/- 4.6, Vmax (degrees/s) = 578.0 +/- 97.4, root-mean-squared error(%) = 5.4 +/- 1.6. The two techniques of parametrisation provided similar indices of intra-individual variability in 4 healthy volunteers. In conclusion, our methods for saccade parametrisation can be regarded as simple but efficient tools for facilitating research on these ocular movements.

Adult↗

PubMed2000

Motion perception during saccadic eye movements.

During rapid eye movements, motion of the stationary world is generally not perceived despite displacement of the whole image on the retina. Here we report that during saccades, human observers sensed visual motion of patterns with low spatial frequency. The effect was greatest when the stimulus was spatiotemporally optimal for motion detection by the magnocellular pathway. Adaptation experiments demonstrated dependence of this intrasaccadic motion percept on activation of direction-selective mechanisms. Even two-dimensional complex motion percepts requiring spatial integration of early motion signals were observed during saccades. These results indicate that the magnocellular pathway functions during saccades, and that only spatiotemporal limitations of visual motion perception are important in suppressing awareness of intrasaccadic motion signals.

Acoustic Stimulation↗

PubMed1998

An enquiry into the relationship between activation and performance using saccadic eye movement parameters.

Saccadic eye movement was measured in three studies in a tracking task in which increasing stimulus jumping frequency indicates increasing difficulty. In the first study, after taking a benzodiazepine 16 subjects showed decreased saccadic velocity (activation indicator), but their reaction times and anticipatory behaviour (performance indicators) did not parallel this decline, although the saccadic amplitudes did. In the second deactivation study 23 subjects worked on somewhat boring oculomotor tasks for 2 h and showed the same decrease in saccadic velocity but showed almost no performance decline. In the third study a large sample of 254 subjects performed the same short tracking task, which offered the detailed analysis of the correspondence of the saccadic activation indicator to saccadic performance indicators. Almost all correlations were zero correlations. Thus, while performance seems to be practically independent of changing activation, the latter is dependent upon performance from one moment to the next. Stable differences were found between anticipatory and reactive saccades, which indicate an immediate change of saccadic velocity when the response mode changes. Therefore a reformulation of the relationship between performance and activation is proposed. Performance is stabilized by 'concentration' in a two-stage regulation process, i.e., it resists changing activation (for example through fatigue). In the second stage, the 'effort loop', additional brainstem activation is demanded when concentration alone fails to reach the goals that were set by the subject for his performance.

Adult↗

PubMed1989

Effects of physostigmine infusion on healthy volunteers deprived of rapid eye movement sleep.

Rapid eye movement sleep (REMS) deprivation is believed to alter the sensitivity of various neurotransmitter systems. In the present article, we studied 20 healthy volunteers divided into three groups. Group A attended the sleep laboratory for three nights: acclimatization, a baseline night, and one night of physostigmine infusion. Group B attended for eight nights; acclimatization, baseline, four nights of REMS deprivation, and two recovery nights. With the exception of the first recovery night, when group C volunteers were administered physostigmine, group C's schedule was identical to group B's. The infusions received by group A and C were composed of 1.0 mg of physostigmine, dissolved in 100 ml of saline solution. These were administered 5 min after sleep onset and thereafter every hour, except when the subjects were either awake or in REMS. All of the subjects receiving the cholinomimetic infusion were given a peripheral anticholinergic. Group A experienced a great number of awakenings with a decrease in REMS percentage. Group B recovery occurred over two nights, with an increase in the average length of REMS. Group C exhibited maximum REMS rebound on the first recovery night with an increased number of REMS episodes, as well as significant reductions in the first REMS latency. Our findings suggest that physostigmine alters REMS rebound following REMS deprivation.

Adolescent↗

PubMed1999

M2 muscarinic receptor subtype in the feline medial pontine reticular formation modulates the amount of rapid eye movement sleep.

Rapid eye movement (REM) sleep is generated, in part, by activating muscarinic cholinergic receptors (mAChRs) in the medial pontine reticular formation (mPRF). Molecular cloning has identified five mAChR subtypes, and this study tested the hypothesis that the M2 subtype in the mPRF modulates the amount of REM sleep. This hypothesis cannot be tested directly, due to lack of subtype selective muscarinic agonists. However, the amount of REM sleep can be enhanced by mPRF microinjection of a muscarinic agonist, and the relative potencies of muscarinic antagonists to block the REM sleep enhancement can be determined. Two muscarinic antagonists, methoctramine and 4-DAMP, were studied. Six concentrations of each antagonist were microinjected into the mPRF of conscious cat 15 min prior to the agonist bethanechol. Nonlinear regression analysis was used to calculate the dose of antagonist that caused a 50% inhibition (ID50) of bethanechol-induced REM sleep. Bethanechol significantly increased (442%) the amount of time spent in REM sleep. Both methoctramine and 4-DAMP significantly blocked the bethanechol-induced REM sleep increase, with an ID50 of 1.8 microM and 0.6 microM, respectively. The ID50 ratio for methoctramine-to-4-DAMP (3.0) was similar to the affinity ratio of methoctramine-to-4-DAMP only at the M2 subtype (3.5), suggesting that the M2 subtype in the mPRF modulates the amount of REM sleep. This study also tested the null hypothesis that sleep-dependent respiratory depression evoked by mPRF cholinomimetics would not be antagonized by pretreatment of the mPRF with muscarinic antagonists. Neither methoctramine nor 4-DAMP antagonized the bethanechol-induced decrease in respiratory rate.

Animals↗

PubMedDate not supplied

[The oculomotor system--simulation of physiologic and pathologic horizontal saccadic eye movements].

Horizontal saccadic eye movements were analyzed by way of the input- and output-functions of the oculomotor system. On the basis of the parameters of the model, it was possible to simulate both physiological and pathological saccades. In this paper we present the results of simulation experiments that were performed to study the influence of various ocular motor disorders. The parameters of the model proved a useful diagnostic aid.

Adult↗

PubMed1987

Voluntary smooth eye movements with foveally stabilized targets.

We investigated the capacity of 6 humans to make voluntary smooth eye movements with a horizontally stabilized foveal point target. When the target was viewed on a dark field, all subjects were able to make smooth oscillatory eye movements when they attempted to imitate their own normal pursuit of sinusoidal target movement (0.2-0.7 Hz) directly preceding the stabilization on the fovea. The frequency of the imitating eye movement was in general lower than the frequency of normal pursuit by 2-35%. While fixating a foveally stabilized point target superimposed on a large, sinusoidally moving non-stabilized background, all subjects were able to make either no eye movements, eye movements nearly in phase with or eye movements nearly in counterphase with the background movement depending on the instruction to imagine the target as head-stationary, moving in phase, or moving in counterphase with the background. The accuracy of the frequency of the smooth eye movement with the stabilized target on the moving background was higher than during imitation of pursuit on the dark field but the precision of the frequency was lower than during normal pursuit. When the background moved pseudo-randomly all subjects could voluntarily inhibit their smooth eye movements or could make smooth eye movements in phase with the background. Only 2 subjects showed a limited ability to make smooth eye movements opposite to the pseudo-random background movement. The results suggest that with predictable background movement the volition of the subject rather than the movement of the background determines the eye movements when the subject looks at the foveally stabilized target.

Eye Movements↗

PubMed1993

[Slow eye movements (slow saccades) in Wilson's disease].

Slow eye movements or slow saccades are relatively rare conditions in Wilson's disease where selective impairments of saccades are observed. The authors have a case of Wilson's disease showing a defect of saccades in all directions, with the complete preservation of smooth pursuit eye movements. T2-weighted images revealed abnormalities of signal intensity in bilateral pontine tegmentum, besides putaminal and thalamic lesions commonly seen in the previous reports. A rather selective disturbance of saccade eye movements due to the pontine tegmentum is consistent with the concept, as yet mainly based on experimental work on animals, of an anatomical segregation of the brainstem pathways for smooth pursuit eye movements, saccades, and vestibular and optokinetic patterns. Whereas the basal brainstem, especially basal pons, subserves smooth pursuit eye movements, saccades and reflex-like eye movements are mediated by the pontine tegmentum. The authors' case offers a support that dissociating eye movement disorders are due to the restricted lesions mentioned above.

Adult↗

PubMed2005

Smooth pursuit eye movements in children.

Smooth pursuit eye movements consists of slow eye movements that approximate the velocity of the eyes to that of a small moving target, so that target image is kept at or near the fovea. Little information on smooth pursuit is available in children. We used an infrared eye tracker to record smooth pursuit in 38 typically developing children, aged 8-19 years. Participants followed a visual target moving sinusoidally at +/-10 degrees amplitude, horizontally and vertically at 0.25 or 0.5 Hz. The mean horizontal smooth pursuit gains, the ratio of eye to target velocities, were 0.84 at 0.25 Hz and 0.73 at 0.5 Hz. Mean vertical smooth pursuit gains were 0.68 at 0.25 Hz and 0.45 at 0.5 Hz. Smooth pursuit gains were significantly lower for vertical in comparison to horizontal tracking, and for 0.5 Hz in comparison to 0.25 Hz tracking (P<0.0001). Smooth pursuit gains increased with age (P<0.01, Pearson's correlation tests), with horizontal gains attaining reported adult values by mid adolescence. Vertical gains had large variability among participants. The median phase, the time interval between eye and target velocities, varied between 39 and 86 ms. Phase was not influenced by age. We conclude that smooth pursuit gains are lower in children than gains reported in adults. Vertical pursuit gain is significantly lower than horizontal pursuit gain. Gains improve with age and approach adult values in mid adolescence. Children have larger phases than reported adults values indicating that prediction in the smooth pursuit system is less mature in children.

Adolescent↗

PubMed1976

Electrocorticography of waves associated with eye movements in man during wakefulness.

Waves associated with horizontal saccadic eye movements were recorded from cortical occipital areas through multilead intracerebral electrodes implanted for a few days in 6 drug-resistant epileptic patients in order to localize epileptogenic foci. The waves were studied statistically when the EEG activity was not disturbed by interictal discharges. Cortical occipital waves related to free eye movements while scanning complex material started at the end of the eye movement, later in fact than the corresponding scalp parieto-occipital phenomena. The amplitude of the cortical waves increased with the complexity of the external field (contrasts having no marked effect) and was reduced in an unpatterned field and in dim light. Waves persisted in darkness. Their amplitude was independent of the size of the eye movement. The latency of the waves, calculated from the onset of eye movement, increased with the size of the movement, the complexity of the external field and also in darkness. Imposed eye movements induced cortical waves of larger amplitude and shorter latency and anticipatory potential changes beginning before onset of the eye movement. Waves related to eye movements differed from blinks and from responses to several types of light stimulation more strikingly in cortical records than in those from the scalp. These findings are discussed in relation to lambda waves, activation waves and eye movement potentials, expectancy waves and premotor potentials, and to the phenomena of perceptual blanks preceding normal perception after fixation of gaze. The importance of the subject's attention is emphasized.

Adolescent↗

PubMed1992

The effects of maturation on spontaneous eye movements in the macaque monkey.

The spontaneous eye movements of infant and adult monkeys were studied both in the dark and in the laboratory light by a magnetic search-coil technique and analysed comparatively. The spatio-temporal organization of the infant monkey's eye movements is predominantly vertical; by contrast it is predominantly horizontal in adults. Moreover, the infant monkey's eye movements have smaller amplitudes and slower velocities than adult's in both visual conditions. The linear relationships between amplitude and maximum velocity suggest that rapid eye movements of the infant monkey are saccades but with a lower rate of velocity increase than the adult's. We conclude that the eye movements in the infant and in the adult monkeys differ in many aspects and that maturation acts on both the static and dynamic characteristics of ocular motility.

Aging↗

PubMed2000

Rapid eye movements during paradoxical sleep in patients with cerebrovascular disease.

Rapid eye movements that occur during paradoxical sleep are generated from the brainstem and are modulated by cerebral hemispheres. In an attempt to establish the participation of cerebral hemispheres on rapid eye movements, we carried out a quantitative study of eye movements density in patients bearing hemispheres vascular lesions. The polysomnographic recordings of 24 patients were compared to those of 24 healthy volunteers. Density of rapid eye movements was defined as the percentage of eye movements during the respective time of paradoxical sleep. Based on the present results, we concluded that: stroke patients with hemispheric lesions displayed increased density of rapid eye movements; there was no difference on the density of rapid eye movements according to the hemispheric lesion; higher density of rapid eye movements was observed in patients with anterior hemispheric lesion.

Adult↗

PubMed2003

Eye movements evoked by the selective stimulation of the utricular nerve in cats.

OBJECTIVE: Eye movements evoked by otolith organ are not well-investigated compare with canal related eye movements due to the technical difficulties. We try to solve this problem by means of our methods. METHODS: Eye movements evoked by selective utricular (UT) nerve stimulation were investigated using both electrooculography (EOG) and video recording in decerebrated cats in the presence or absence of anesthesia. Electrical stimulation was applied to the UT nerve through implanted acupuncture needles. RESULTS: In the absence of anesthesia and with stimulus intensities less than 2.6+/-0.7 x N(1)T, we found ipsilaterally directed horizontal eye movements in both eyes in one cat, abduction in the ipsilateral eye in two cats, and adduction in the contralateral eye in another cat. Other types of eye movements (e.g., supraduction or diagonal eye movements) were observed in both eyes of cats in the absence of anesthesia at a stimulus intensity of 12.2+/-7.6 x N(1)T, an intensity in which current spread to the adjacent nerve could not be ruled out. In the presence of anesthesia, UT nerve stimulation alone failed to evoke horizontal eye movements, but with an intensity 13.8+/-6.4 x N(1)T, supraduction or diagonal eye movements were evoked. UT nerve stimulation at 2-3 x N(1)T facilitated horizontal eye movements induced by ipsilateral abducens (AB) nucleus stimulation or contralateral horizontal canal nerve stimulation. CONCLUSION: This is the first report to our knowledge in which UT nerve-evoked horizontal eye movements are documented. These results confirm the known monosynaptic and disynaptic anatomical connections from utricular primary afferents to the ipsilateral AB nucleus neurons.

Abducens Nerve↗

PubMed2006

[Diagnosis of supranuclear eye movement disorders. Part II: Vertical and torsional oculomotoricity].

The hallmark of a supranuclear eye movement disorder is functional impairment of one or several types of different eye movements while other types of eye movement remain unchanged. All eye movement information is conveyed via the nuclei of the eye muscle nerves. However, the information for a specific type of eye movement is generated in prenuclear cortical and subcortical areas which are activated depending on the type of eye movement performed. The structures responsible for vertical and torsional oculomotoricity are described as well as the functional relationship between them. A summary of the development of saccades and movements arising from them is also given and the influence of the cerebellum on oculomotor processes is dealt with. In many neurological conditions knowledge about the areas of the brain relevant for eye movement enables a clinical diagnosis to be made or the pathological process to be localized to a specific anatomical area. Examination of eye movements is thus a valuable clinical tool in many neurological and neuro-ophthalmological diseases.

Brain Stem↗

PubMedDate not supplied

The plasticity of compensatory eye movements in rotatory tests. I. The effect of alertness and eye closure.

Fifteen voluntary subjects with a mean age of 26 years (17-39), participated in two rotatory experiments. The rotatory test used was sinusoidal harmonic acceleration (SHA) test at frequencies of 0.01-0.32 Hz. Compensatory eye movements were measured by means of EOG. Experiment A included rotation in darkness during alerting tasks (day 1), rotation in darkness with no tasks (day 2) and rotation in darkness during alerting tasks (day 3). In the alertness tests, the gain varied between 0.5 and 0.77. Phase values decreased with increasing frequency. The alertness results between days 1 and 3 did not differ in gain or phase. The gain of day 2 (no tasks) displayed significantly reduced gain at all frequencies, and a more pronounced decrease in phase than in the alertness tests. Experiment B comprised testing with eyes open (day 1) and eyes closed (day 2) during alerting tasks. These tests displayed significantly decreased gain at all frequencies with eyes closed compared with eyes open and with more negative phase at 0.08-0.32 Hz with eyes closed. The results indicate a central effect of the alertness level on compensatory eye movements, and the effect of eye closure might be explained by bio-mechanical and possibly even central effects on the eye movements. In low-frequency testing, as short a test time as possible should be used, and due to different alertness levels, the results should be evaluated with great caution.

Acceleration↗