Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Eye Movement Measurements”

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.

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

At least 343 records · Page 19Linked to original sources
PubMed2005

The influence of age and gender on the latency of eye movement in healthy humans.

Standard measures of sleep recordings give differing results depending on the gender and they constantly change with age. Sleep latency increases, delta sleep decreases, and sleep tend to be shorter in duration and fragmented in middle-aged and elderly adults. The deterioration of sleep is observed earlier in men. In the 1980s, new measures called the Latency of Eye Movement (LEM) and the Mean Latency of Eye Movement (M-LEM) were proposed. Previous studies have shown that untreated patients with endogenous depression had the LEM and M-LEM shortened and that both indices get prolonged during treatment with antidepressants. On the other side, alcoholics in the abstinence period have LEM and M-LEM twice as long as healthy controls. In this study we set out to compare LEM and M-LEM in healthy humans according to the gender and age. The subjects of the study were 80 healthy volunteers: 40 males and 40 females, who were divided into 4 groups: females and males, below and above 40 years of age. In contrast to standard measures, our study did not reveal any significant changes of LEM or M-LEM due to the gender or age.

Adult↗
PubMed2002

Saccadic peak velocity and EEG as end-points for a serotonergic challenge test.

UNLABELLED: We previously reported that a single dose of the serotonin receptor agonist meta-chlorophenylpiperazine increased the peak velocity of saccadic eye movements and decreased low-frequency electroencephalographic activity. METHODS: We administered a single dose of the serotonin releaser dexfenfluramine in a double blind, placebo controlled randomised cross-over design and measured saccadic eye movements and EEG every hour up to 6 h. Subjects were 62 males (18-30 years) with a history of no, moderate or heavy use of ecstasy tablets. RESULTS: Dexfenfluramine increased saccadic peak velocity and decreased alpha, delta and theta electroencephalographic activity, the latter predominantly in heavy users of ecstasy. CONCLUSIONS: This study supports the idea that saccadic peak velocity and EEG can be useful endpoints of a serotonergic challenge. This could be an important anatomical extension of these end-points, which until now were limited to the effect on hypothalamic serotonergic projections.

Adolescent↗
PubMed1975

Conjugate lateral eye movement and latency of verbal response to arithmetic questions.

24 left movers, 24 right movers and 24 mixed movers, categorized on the basis of their conjugate lateral eye movements, were measured on latency of verbal response to arithmetic questions. The predicted superiority of right movers in speed of response did not occur nor did interference with habitual direction of conjugate lateral eye movement affect results. However, the mixed group took longer to response to a second series of questions than did the left and right movers. This post hoc finding may indicate inefficient hemispheric competition within the mixed group when subjects are asked to add another task to that of arithmetic problem-solving.

Adult↗
PubMed1996

Behavioural and electrophysiological chromatic and achromatic contrast sensitivity in an achromatopsic patient.

OBJECTIVES: In cases of incomplete achromatopsia it is unclear whether residual visual function is mediated by intact striate cortex or results from incomplete lesions to extrastriate cortical visual areas. A patient with complete cerebral achromatopsia was tested to establish the nature of his residual vision and to determine the integrity of striate cortex function. METHODS: Behavioural contrast sensitivity, using the method of adjustment, and averaged visually evoked cortical potentials were measured to sinusoidally modulated chromatic and achromatic gratings in an achromatopsic patient and a normal observer. Eye movements were measured in the patient using a Skalar infrared monitoring system. RESULTS: The patient's chromatic contrast sensitivity was normal, indicating that despite his dense colour blindness his occipital cortex still processed information about spatial variations in hue. His sensitivity to achromatic gratings was depressed particularly at high spatial frequencies, possibly because of his jerk nystagmus. These behavioural results were reinforced by the nature of visually evoked responses to chromatic and achromatic gratings, in which total colour blindness coexisted with an almost normal cortical potential to isoluminant chromatic gratings. CONCLUSIONS: The results show that information about chromatic contrast is present in some cortical areas, and coded in a colour-opponent fashion, in the absence of any perceptual experience of colour.

Adult↗
PubMed2004

Torsional eye movements during psychophysical testing with rotating patterns.

Torsional eye movements were measured while subjects viewed a large, high contrast windmill pattern rotating at 53 degrees /s or a small (5 degrees diameter) dot pattern rotating at 115 degrees /s. Both stimuli generated rotational eye movements consisting of torsional optokinetic nystagmus (tOKN) superimposed on a slow torsional drift in the direction of pattern rotation. With the wide-field windmill stimulus, torsional drifts of up to 7 degrees over 20 s were found. The dot pattern produced drifts of up to 2 degrees over 5-20 s. In both cases, the slow-phase speeds during tOKN were low (0.5-1 degrees /s). We conclude that reductions in slip speed are minimal with rotating stimuli, so torsional eye speeds will have a minimal effect on investigations of rotational motion aftereffect strength and perceived speed. While the slow-phase tOKN gain is low, the slow drift in torsional eye position will have significant effects on psychophysical results when the tests rely on keeping selected regions of the stimulus confined to specific areas of the retina, as is the case for phantom or remote motion aftereffects.

Eye Movements↗
PubMed1980

Vestibulo-ocular reflexes in rabbits: reduction by intravenous injection of diazepam.

We have studied the influence of intravenously administered diazepam on the horizontal (HVOR) and vertical (VVOR) vestibulo-ocular reflexes of the rabbit. The HVOR and VVOR were evoked by sinusoidal oscillation of rabbits on a rate table (0.01 to 0.8 Hz, +/- 10 degrees), and eye movements were measured with an infrared light-projection technique. The gains of the HVOR and VVOR (evoked eye velocity/head velocity) were reduced by diazepam injections of 5 microgram/kg. The dose required to produce a 50% reduction in HVOR gain was 500 microgram/kg. The time required to reduce the HVOR gain to 50% of its maximal reduction at dose of 400 microgram/kg (0.4 Hz +/- 10 degrees) was 60 s. These data suggest that diazepam might be effective as an anti-motion-sickness agent.

Animals↗
PubMed2003

The effects of pitch tilt on postrotatory nystagmus in cats.

When the head is tilted away from the upright position immediately after termination of earth-vertical axis (EVA) head rotation at a constant velocity, the rotation axis of postrotatory nystagmus (PRN) is gradually directed toward gravity (spatial reorientation). During roll tilt, the extent of the axis shift varies among species. In cats, the reorientation is limited to about 30-45 degrees of head tilt. In the present study, we examined features of PRN during pitch tilt in cats. The animals were rotated about EVA at a constant velocity of 100 degrees /s for 120 s. Within 2 s after stopping EVA rotation, the animals were tilted toward the pitch plane by as much as +/-90 degrees (nose-down or nose-up) in steps of 15 degrees. Eye movements were measured with 3D magnetic search coils. The angle of the PRN plane and its slow phase eye velocity (SPV) were measured. The duration of PRN decreased as pitch tilt increased regardless of whether the direction was nose-up or nose-down. The mean time constant of SPV was significantly longer for nose-up than for nose-down. PRN maintained its horizontal orientation without any vertical drift during pitch tilt, but there was little reorientation toward gravity. That is, no significant torsional component of SPV emerged to reorient the eyes according to gravity. Our results indicate that spatial reorientation depends on head orientation. For the PRN responses after pitch tilts in cats, the interactions of semicircular canal and otolith inputs in the central vestibular system might be vestigial.

Animals↗
PubMed2003

Measuring word recognition in reading: eye movements and event-related potentials.

The investigation of visual word recognition has been a major accomplishment of cognitive science. Two on-line methodologies, eye movements and event-related potentials, stand out in the search for the holy grail - an absolute time measure of when, how and why we recognize visual words while reading. Although each technique has its own experimental limitations, we suggest, by means of review and comparison, that these two methodologies can be used in complementary ways to produce a better picture of the mental action we call reading.

Journal Article↗
PubMed1999

Attentional localization prior to simple and directed manual responses.

The relationship between attention and the programming of motor responses was investigated, using a paradigm in which the onsets of targets for movements were preceded by peripheral attentional cues. Simple (button release) and reaching manual responses were compared under conditions in which the subjects either made saccades toward the target location or refrained from making eye movements. The timing of the movement onset was used as the dependent measure for both simple and reaching manual responses. Eye movement latencies were also measured. A follow-up experiment measured the effect of the same peripheral cuing procedure on purely visual processes, using signal detection measures of visual sensitivity and response bias. The results of the first experiment showed that reaction time (RT) increased with the distance between the cued and the target locations. Stronger distance effects were observed when goal-directed responses were required, which suggests enhanced attentional localization of target positions under these conditions. The requirement to generate an eye movement response was found to delay simple manual RTs. However, mean reaching RTs were unaffected by the eye movement condition. Distance gradients on eye movement latencies were relatively shallow, as compared with those on goal-directed manual responses. The second experiment showed that the peripheral cue had only a very small effect on visual detection sensitivity in the absence of directed motor responses. It is concluded that cue-target distance effects with peripheral cues are modulated by the motor-programming requirements of the task. The effect of the peripheral cue on eye movement latencies was qualitatively different from that observed on manual RTs, indicating the existence of separate neural representations underlying both response types. At the same time, the interactions between response modalities are consistent with a supramodal representation of attentional space, within which different motor programs may interact.

Adult↗
PubMed1996

Disturbed eye movements after whiplash due to injuries to the posture control system.

Self-reports after whiplash often indicate associations with vertigo and reading problems. Neuropsychological and otoneurological tests were applied to a group of whiplash patients (n = 26) and to a carefully matched control group. The whiplash group deviated from the control group on measures of eye movements during reading, on smooth pursuit eye movements with the head in normal position, and with the body turned to the left or to the right. Clinical, caloric, and neurophysiological tests showed no injury to the vestibular system or to the CNS. Test results suggest that injuries to the neck due to whiplash can cause distortion of the posture control system as a result of disorganized neck proprioceptive activity.

Adult↗
PubMed1988

Comparison for aphasic and control subjects of eye movements hypothesized in neurolinguistic programming.

Neurolinguistic programming's hypothesized eye movements were measured independently using videotapes of 10 nonfluent aphasic and 10 control subjects matched for age and sex. Chi-squared analysis indicated that eye-position responses were significantly different for the groups. Although earlier research has not supported the hypothesized eye positions for normal subjects, the present findings support the contention that eye-position responses may differ between neurologically normal and aphasic individuals.

Aphasia↗
PubMed1995

[A battery model of the eyeball to calculate standing potential of the eye].

Variation of the resting potential caused by eye movements was analyzed by applying a battery model to the eyeball. A formula that gives the potential between the inner canthus and the outer canthus of the eye was derived on the basis of the electric theory in electromagnetics, on the assumption that the eyeball was floating in a homogeneous conductor. The variations of the resting potentials were represented using the distance from the center of the eyeball to the potential detecting position and the deflection angle of the position with respect to the optical axis of the eyeball. To verify the validity of the formula, the variation of the resting potential caused by the various amplitudes of bilaterally symmetrical eye movements were measured. The calculated results were found to be in good agreement with the experimental ones.

Electrooculography↗
PubMed1986

Functional development of human eye movement in utero assessed quantitatively with real-time ultrasound.

Functional development of eye movement in the human fetus in utero was assessed quantitatively, with real-time ultrasound. A pair of lens-derived echoes was used as a landmark to evaluate positional deviation with eye movement. The frequency of eye movement was measured either with 1-minute continuous observations or at 1-minute cross sections. Two hundred forty-five normal fetuses between 18 and 42 weeks of gestation were studied. Three critical ages, with respect to physiologic development of fetal eye movements, were evident: 22 to 25, 30 to 33, and 38 to 41 weeks. The first and the second indicate the onset of the moderate-frequency and high-frequency eye movements, thereby implying a transition, presumably to a state of so-called rapid eye movement and a rise of rapid eye movement, respectively. The third represents full maturation of the mechanisms, that is, non-rapid eye movement and rapid eye movement.

Eye Movements↗
PubMed1995

[Quantitative analysis of smooth pursuit eye movement].

Abnormalities of smooth pursuit eye movement (SPEM) have been estimated, mainly using the wave form on an electro-oculogram, in a qualitative way. Many methods for quantitative analysis of SPEM have been designed, though most are still uncommon in present clinical use. Using a personal computer, we developed a method of automatic quantitative analysis of ocular tracking eye movement recorded by electro-oculography (EOG). The design concept of this method is based on the observation that eye movement during ocular tracking consists of two different kinds of eye movements, one is SPEM and the other is saccade. The combination of SPEM and saccade (composite eye movement: CEM) commonly appears during ocular tracking. These two kinds of eye movement are essentially different not only in behavior but also about involved neural pathway in the central nervous system. From this point of view, we believe that the two kinds of eye movements involved in ocular tracking should be evaluated separately. The analysis method is outlined as follows. A horizontal sinusoidally moving visual target was employed to elicit ocular tracking eye movements. The test frequencies were set at 0.1, 0.2, 0.4 and 0.8Hz, and the amplitude of target motion was 15 deg at each frequency. The 20 seconds of eye movement data measured by EOG were fed into the computer through a digital-analog converter for further analysis. Using our original saccade detection algorithm, based on the physiological behavior of saccades, the saccadic components were detected and removed from the eye movement wave. The remaining parts, fragments of SPEM, were connected by means of interpolating defective parts. The reconstructed wave was a slow cumulative eye position curve (SCEP). Sinusoidal target motion, CEM and SCEP were processed by the FFT (Fast Fourier Transformation) method. Bode plots were applied to summarize the gain and phase of responses to SCEP and the target motion wave. These processes enable us to estimate abnormalities of SPEM such as low gain, abnormal phase shift and large trends in tested duration. We conclude that the method described here is useful for quantitative estimation of SPEM in clinical neuro-otological examinations.

Adult↗
PubMed2006

Levodopa slows prosaccades and improves antisaccades: an eye movement study in Parkinson's disease.

BACKGROUND: The integrity of frontal systems responsible for voluntary control and their interaction with subcortical regions involved in reflexive responses were studied in patients with Parkinson's disease (PD). Previous studies have shown that patients with PD have impaired executive function, including deficits in attention, motor planning and decision making. METHODS: Executive function was measured through eye movements: reflexive (stimulus driven) prosaccades and voluntary (internally guided) antisaccades. Patients with advanced idiopathic PD, off and on their optimal levodopa therapy, were tested on a prosaccade and an antisaccade task and compared with matched controls. RESULTS: Levodopa significantly increased response time for reflexive prosaccades and reduced error rate for voluntary antisaccades. CONCLUSIONS: Consistent with our proposed model, patients with PD in the medicated state are better able to plan and execute voluntary eye movements. These findings suggest levodopa improves function of the voluntary frontostriatal system, which is deficient in PD.

Aged↗
PubMedDate not supplied

Simulation of eye-tracker latency, spot size, and ablation pulse depth on the correction of higher order wavefront aberrations with scanning spot laser systems.

PURPOSE: The aim of this theoretical work was to investigate the robustness of scanning spot laser treatments with different laser spot diameters and peak ablation depths in case of incomplete compensation of eye movements due to eye-tracker latency. METHODS: Scanning spot corrections of 3rd to 5th Zernike order wavefront errors were numerically simulated. Measured eye-movement data were used to calculate the positioning error of each laser shot assuming eye-tracker latencies of 0, 5, 30, and 100 ms, and for the case of no eye tracking. The single spot ablation depth ranged from 0.25 to 1.0 microm and the spot diameter from 250 to 1000 microm. The quality of the ablation was rated by the postoperative surface variance and the Strehl intensity ratio, which was calculated after a low-pass filter was applied to simulate epithelial surface smoothing. RESULTS: Treatments performed with nearly ideal eye tracking (latency approximately 0) provide the best results with a small laser spot (0.25 mm) and a small ablation depth (250 microm). However, combinations of a large spot diameter (1000 microm) and a small ablation depth per pulse (0.25 microm) yield the better results for latencies above a certain threshold to be determined specifically. Treatments performed with tracker latencies in the order of 100 ms yield similar results as treatments done completely without eye-movement compensation. CONCWSIONS: Reduction of spot diameter was shown to make the correction more susceptible to eye movement induced error. A smaller spot size is only beneficial when eye movement is neutralized with a tracking system with a latency <5 ms.

Computer Simulation↗
PubMed2003

Gaze behavior while crossing complex intersections.

BACKGROUND: Crossing the street is a complex task that involves gathering, processing, and acting on information that is time dependent. The gaze behavior of subjects has been previously studied on increasingly complex and dynamic tasks such as making tea, walking indoors, and driving. The purpose of this study was to assess how normally sighted people use their vision to cross a street safely. Specifically, we identified the environmental features people look at when crossing two types of intersections. METHOD: We measured the eye movements and head directions of 12 normally sighted people as they approached, evaluated, and crossed a light-controlled "plus" intersection and a roundabout. The primary measures were percentage of fixations and head direction. RESULTS: Crossing the street can be divided into three phases, walking to the curb, standing at the curb, and crossing the street. We found that while moving, subjects fixated primarily on crossing elements and when standing at the curb, they fixated primarily on vehicles. At the plus intersection, fixation behavior corresponded with crossing strategy; the subjects who crossed early fixated on cars, and the subjects who waited for the light to change fixated on traffic controls. At the roundabout, all subjects determined an appropriate time to cross from vehicular traffic flow by directing the majority of their fixations on cars. When moving, the head position of subjects was predominately centered. Subjects also made head turns in both directions before crossing and directed the head toward the danger zone while crossing. CONCLUSION: Crossing the street is a complex task that can be described in three phases. Common head and eye behaviors were found near the critical moments of crossing the street. Fixation behavior was closely related to street crossing behavior.

Adult↗