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Oculomotor function during space flight and susceptibility to space motion sickness.

Horizontal vestibulo-ocular reflex (VOR) and saccadic eye movements (SEM) were studied in 18 subjects before and during five Space Shuttle missions to evaluate the effects of weightlessness and correlations between results and susceptibility to and actual presence of space motion sickness (SMS). Active sinusoidal head oscillation was the stimulus for VOR tests with vision (VVOR), with eyes shaded (VOR-ES), and VOR suppression (VOR-S). Eye movements were recorded by electrooculography and head position by a potentiometer. No pathological nystagmus or other abnormal eye movements were seen. No significant in-flight changes were seen in the gain, phase shift or waveform of VVOR, VOR-ES, or VOR-S. Statistically significant increases in saccadic latency and decreases in saccadic velocity were seen, with no change in saccadic accuracy. Preflight differences between SMS susceptible and non-susceptible subjects were noted only in VOR-S, with less complete suppression in susceptible subjects, a finding also seen in flight. During flight, VVOR gain was significantly increased in three non-affected subjects. Saccades of SMS-affected subjects showed increased latency and velocity and decreased accuracy compared to saccades of unaffected subjects.

Adult↗

Modifications of spontaneous oculomotor activity in microgravitational conditions.

Investigations on spontaneous oculomotor activity were carried out prior to and after (five cosmonauts) and during space flight (two cosmonauts) on the 3rd, 5th and 164th days of the space flight. Recording of oculomotor activity was carried out by electrooculography on automated data acquisition and processing system "Zora" based on personal computers. During the space flight and after it all the cosmonauts with the eyes closed or open and dark-goggled showed an essential increase of the movements' amplitude when removing the eyes into the extreme positions especially in a vertical direction, occurrence of correcting saccadic movements (or nystagmus), an increase in time of fixing reactions.

Eye Movements↗

The Usher syndrome type 2A: clinical findings in obligate carriers.

Ten obligate carriers of Usher syndrome type 2A from 5 different families with 2 affected persons all underwent audiologic, vestibular and ophthalmologic examinations. They had a sensorineural hearing loss which was in excess of that expected for their age at all of the frequencies (0.25-8 kHz) tested, however, only a 10 dB (average) excess in hearing loss at 0.25-0.5 kHz proved to be significant. The speech discrimination scores obtained conformed with the hearing thresholds. Tympanometry, acoustic reflex and brain stem auditory-evoked potential findings were generally normal. Some vestibular abnormalities were found in a minority of the carrier sample, but not beyond the level of false positivity. Ophthalmologic findings were essentially normal, although in 5 carriers there was a subnormal electrooculography (EOG). These findings are not sufficient specific for carrier detection.

Acoustic Impedance Tests↗

Biperiden-induced delirium model in rats: a behavioral and electroencephalographic study.

AIMS AND METHODS: In order to elucidate the neural mechanisms of delirium, we administered the anticholinergic drug, biperiden (40 mg/kg i.p.), to 10 adult male Wistar rats and examined the resulting polygraphic recordings, including electroencephalography (EEG), electrooculography (EOG), and electromyography (EMG), for 60 min following injection. EEG data were investigated quantitatively by power spectrum analyses using fast Fourier transformation. Ten male Wistar rats receiving saline (i.p.) were used as the control group. RESULTS: Treated rats demonstrated two types of alternating behavioral change: a hyperactive and hypoactive state. In the hyperactive state, rapid walking, excessive random sniffing, and retropulsion were observed, with EEG desynchronization (significantly increased alpha1 (8.0-10.0 Hz), alpha2 (10.0-13.0 Hz), and beta (13.0-30.0 Hz) power values), as well as EEG slowing (significantly increased delta (0.5-4.0 Hz) and theta1 (4.0-6.0 Hz) power values): significantly marked rapid eye movement, and increased EMG activity. In the hypoactive state, motor arrest and drowsiness were observed, with prominent EEG slowing (significantly increased delta and theta1 power values): significantly decreased rapid eye movement and moderately decreased EMG activity. On the other hand, the control group did not show any behavioral or polygraphic changes. CONCLUSIONS: The behavioral and polygraphic changes induced by biperiden administration in rats are similar to those of delirium in humans. Therefore, it is proposed that biperiden-treated rats are a good delirium model and the anticholinergic mechanism is one of the potent factors in the development of delirium in humans.

Acetylcholine↗

Development of the optokinetic system in macaque monkeys.

Optokinetic nystagmus in response to horizontal movement of a whole field random dot pattern was measured in infant macaque monkeys from the first week to about 5 months after birth using electrooculography. During monocular and binocular viewing conditions stimulus velocities were varied between 10 and 120 degrees/s. Monocular stimulation in the temporonasal direction yielded slow phase gain of the optokinetic system which was relatively constant for a given stimulus velocity over the whole period of observation. Gain during nasotemporal stimulation was also clearly present but significantly lower at early stages and increased during further development. This asymmetry of monocular horizontal optokinetic nystagmus (OKN) clearly depended on the stimulus velocity. At lower stimulus velocities (10-20 degrees/s) OKN was largely symmetrical at 2-5 weeks of age. At higher stimulus velocities (40 degrees/s) symmetry was reached at about 12 weeks of age or even much later (80-120 degrees/s).

Aging↗

Saccadic eye movements in myasthenia gravis.

The peak velocities of horizontal saccades were measured in patients with myasthenia gravis (MG) to determine whether they can differentiate MG from other causes of ophthalmoplegia. Eye movements were recorded with electrooculography (EOG) or infrared scleral reflection (IR) in 42 patients with MG, 26 patients with sixth cranial nerve palsy (CNP), 19 patients with chronic progressive external ophthalmoplegia (PEO) and 28 normal subjects. Despite limitation of ductions in MG, the group means of velocities of 10 deg saccades recorded with IR were similar in MG and normal subjects. With EOG, small but statistically significant decreases in mean velocities of 10, 20 and 30 deg saccades were found in MG, compared to those in normal subjects. Twenty-one to 28% of MG patients had velocities outside of the normal range (outliers). In contrast, the group means in CNP and PEO were markedly lower than those in MG and normal subjects. The frequencies of outliers were 89 to 100% in CNP and 88 to 100% in PEO. Measurement of saccadic velocities can be helpful in differentiating MG from other causes of ophthalmoplegia.

Adolescent↗

Ophthalmologic manifestations of X-linked childhood adrenoleukodystrophy.

The ophthalmologic findings in 15 patients with childhood adrenoleukodystrophy (ALD) are reviewed. In this X-linked demyelinating disease with adrenal dysfunction, relentlessly progressive visual loss followed by optic atrophy occurs months to years after the diagnosis is established based on neurologic symptoms and biochemical abnormalities. Visual loss is mainly due to central nervous system (CNS) demyelination involving the visual tracts, but primary retinal ganglion cell degeneration may also be operative. All patients in this study were male. Vision ranged from 20/20 to no light perception (NLP). All but one patient with bilateral cataracts had normal anterior segment examinations. Seven patients had exotropia, and esotropia developed in one patient. Electroretinography (ERG) and electrooculography (EOG) findings were normal in two patients with severe visual loss. Macular pigmentary changes were observed in three patients. Optic pallor was noticed in seven patients. Optic nerve hypoplasia was seen in one patient. Visual-evoked responses were abnormal in two patients and borderline in one. Progressive visual field abnormalities were noticed in three patients, large field cuts in two patients, and normal fields in another two patients. The diagnosis of ALD should be considered in all boys presenting with unexplained visual loss, dementia, and adrenal dysfunction.

Adolescent↗

Visual impairment caused by retinal abnormalities in mesangiocapillary (membranoproliferative) glomerulonephritis type II ("dense deposit disease").

Patients with mesangiocapillary glomerulonephritis (MCGN) type II usually present by early adulthood with hematuria, proteinuria, and renal impairment, and these features often are accompanied by a partial lipodystrophy and an autoantibody for the alternative complement pathway convertase (C3NeF). The diagnosis of MCGN type II depends on the demonstration of "dense deposits" in the glomerular basement membrane (GBM). Most patients also have multiple subretinal white spots or drusen that are histopathologically identical with the GBM deposits and evident ophthalmoscopically by the time renal failure develops. Initially visual acuity and visual fields are preserved, but fluorescein angiography and specialized tests of retinal function, such as dark adaptation, electroretinography, and electrooculography, may be abnormal and will worsen progressively. Over the next 20 years, vision often deteriorates because of retinal atrophy, and sometimes because of subretinal neovascular membranes, macular detachment, and central serous retinopathy. The authors describe a patient with MCGN type II who presented with renal failure and impaired vision at the age of 59. He already had widespread retinal atrophy, and subsequently a subretinal membrane developed. The drusen seen in MCGN type II, like the partial lipodystrophy, are a helpful clinical pointer to the diagnosis of this condition. All patients with MCGN type II should be warned of the risk of retinal complications and reviewed by an ophthalmologist at presentation and regularly after about 10 years to minimize the loss of visual acuity from complications of the retinopathy.

Atrophy↗

Symptomatic abnormalities of dark adaptation in patients with EFEMP1 retinal dystrophy (Malattia Leventinese/Doyne honeycomb retinal dystrophy).

PURPOSE: To investigate the nature of symptomatic visual disturbance in patients with EFEMP1 retinal dystrophy in the absence of geographic atrophy or choroidal neovascularization. METHODS: Patients presenting to a tertiary referral centre underwent clinical evaluation, fluorescein angiography, colour contrast sensitivity, focal, pattern, and standard electroretinography, electrooculography, scotopic threshold perimetry and dark adaptometry. RESULTS: Clinical features included reduced central vision, difficulty passing from light to dark, and diffuse submacular and peripapillary deposits, which were hyperfluorescent by fluorescein angiography. Colour contrast thresholds were abnormal in all six patients studied and both pattern and focal electroretinograms were abnormal in five of six patients. The scotopic and mixed rod-cone single flash ERG was normal but two patients demonstrated reduced oscillatory potentials and one had borderline delayed 30 Hz responses. Scotopic thresholds were elevated and rod-mediated dark adaptation kinetics were markedly prolonged in all six patients when measured over the central visible confluent deposits. CONCLUSIONS: In patients with EFEMP1 retinal dystrophy with confluent macular deposits, scotopic sensitivity is reduced and dark adaptation kinetics are prolonged over the macular deposits but are normal elsewhere. These results emphasize the localised nature of functional deficits in some patients with EFEMP1 retinal dystrophy and correlate well with the patient's visual symptoms. Symptomatic visual dysfunction may precede the development of clinically evident geographic atrophy or choroidal neovascularization in this disorder.

Color Vision Defects↗

Development and application of the 'Sleep Ukiha' automated sleep analysis system.

We attempted to develop an automated sleep analysis system that uses a personal computer as an aid to the entire sleep research process. Analysis is based on electroencephalogram, chin muscle electromyogram and electrooculography, while other physiological phenomena can be handled arbitrarily. Major characteristics of the system include: (i) simultaneous gathering of physiological phenomena from up to three patients; (ii) high-speed waveform analysis; (iii) user-friendly operating environment through the use of a graphical user interface; and (iv) versatile utilization of analytical data in research.

Humans↗

[Corneoretinal dystrophy (Bietti)-- Long-term course of one patient over a period of 30 years, and interindividual variability of clinical and electrophysiological findings in two patients].

BACKGROUND: A tapetoretinal dystrophy with crystalline deposits of the retina and limbal cornea was described by Bietti in 1937. To date, only a few cases with long-term follow up have been reported. PATIENTS AND METHODS: Two patients are presented including the clinical findings, fluorescein angiography, electrophysiology [electroretinography (ERG); electrooculography (EOG), multifocal electroretinography (MERG)], adaptometry, and transmission electron microscopy (TEM) of peripheral blood lymphocytes. The clinical findings were at least in part documented over a period of 30 years. RESULTS: The most striking features were deposits in the retina and cornea associated with crystalloid lysosomal inclusions in peripheral lymphocytes, and choroidal atrophy especially in advanced stages of the disease. The light rise (EOG), rod- and cone-driven responses (ERG), the responses of the MERG and visual fields were affected progressively during the course. These advanced changes of the retinal pigment epithelium and choriocapillaris were observed in the 2(nd) decade already. CONCLUSIONS: The findings of deposits in the cornea, retina and lymphocytes may help to differentiate BCD from other chorioretinal dystrophies. The results confirm a variable course in clinical expression of BCD between individuals.

Adult↗

[Saccadic reaction times and visuospatial disorders of attention in schizophrenic patients with negative symptoms].

Schizophrenics display various oculomotor disturbances. In this study we investigated saccadic reaction times in 47 unmedicated schizophrenics (ICD-9) as well as 28 age and sex matched normal controls. Using a cluster analysis according to the BPRS we determined two subgroups each with high and low negative symptoms; we expected poorer results from patients with negative symptoms on account of existing attentional deficits. The eye movements were recorded with electrooculography. Stimuli were presented at random with amplitudes of 5 degrees at a minimum and 20 degrees maximally; the distances between the angles were kept as short as possible, and we chose a fast stimulus rate (800, 1.000 and 1.200 ms). Only the group of schizophrenics with pronounced negative symptoms showed significantly delayed saccadic reaction times, whereas other schizophrenic patients did not differ from the controls. An unfavorable course of the illness also was associated with delayed reaction times. The saccadic reaction times were delayed in both the right and left visual field to the same degree. The poorer performance of the schizophrenics with pronounced negative symptoms are being discussed in relation to attentional deficits regarding visuospatial functions.

Adolescent↗

[Infrared reflection method for recording horizontal eye movements. An improved version for routine diagnostic studies].

Basically, the infrared reflection method for recording of horizontal eye movements has been conceived in the fifties already. The method has proved to be a valuable tool for recording of eye movements, particularly saccades. More recently there is increasing interest in recording of horizontal saccades for diagnostic purposes. Previous versions of this method, however, were not suitable for routine recordings. After several technical improvements the method now is ready for routine recordings of horizontal eye movements in the diagnosis of neurological and opthalmological disorders. In order to accentuate the strengths and weaknesses of the infrared reflection method, it is compared with DC-Electrooculography.

Eye Movements↗

[Animal models for the optokinetic system of the human].

BACKGROUND: We compare the neuronal and behavioural consequences of abnormal visual experience during early infancy for the optokinetic system of cat and monkey with the neuroopthalmological results in man. MATERIAL AND METHODS: Optokinetic eye movements were recorded with the search coil method and electrooculography. In addition, the response properties of single neurons in the visual cortex and pretectum of anesthetized and paralyzed cats and monkeys were determined in electrophysiological experiments. RESULTS: Our data show that monocular deprivation and strabismus lead to an increase of asymmetry of monocular optokinetic nystagmus and a decrease in gain of slow phase optokinetic eye movements during monocular stimulation as well as to a significant decrease of binocular convergence in the oculomotor system of both cat and monkey. Although these changes are basically similar in both species they are not identical. These differential effects may be explained by structural differences. CONCLUSIONS: Assuming a similar neuronal substrate for the optokinetic system in all primates the monkey represents a more suitable animal model for the human visual system than the cat.

Animals↗

Effects of an electric blanket on sleep stages and body temperature in young men.

The aim of this study was to investigate any effects of electric blanket on sleep stages and body temperature. Nine male subjects slept under two conditions: using the electric blanket (HB); and not using the electric blanket (C). The ambient condition was controlled at 3 degrees C relative humidity 50-80%. Electroencephalography, electrooculography (EOG) and electromyography, rectal temperature, skin temperature and microclimate temperature and humidity were recorded continuously through the night. Body weight was measured before and after sleep. The amount of stage 1 and number of stage 1 and rapid eye movement sleep decreased in HB compared to C. No significant difference was observed in other sleep stages. Rectal temperature was higher in HB compared to C. The thigh, leg and foot skin temperature was higher in HB than C. The microclimate temperature of the foot area was higher in HB compared to C. No significant difference was observed in whole body sweat loss between the conditions. These results suggest that use of an electric blanket under low ambient temperature may decrease cold stress to support sleep stability and thermoregulation during sleep.

Adult↗

Hand, eye, and head coordination while pointing to perturbed targets.

Normal human subjects were required to manually point to small visual targets that suddenly changed location upon finger movement initiation. They pointed either as fast or as accurately as possible. Movements of the eyes were measured by electrooculography, and the movements of the unrestrained limb and head were monitored by an optoelectric system (WATSMART), which allowed for the analysis of kinematic parameters in three-dimensional space. The temporal and kinematic reorganization of each body part in response to the target perturbations were variable, which indicated independent control for each part of the system. That is, the timing and nature of the reorganization varied for each body part. In addition, the pattern of reorganization depended upon the speed and accuracy demands of the movement task. As well, the movement termination patterns (eyes finished first, the finger reached the target, then the head stopped moving) were extremely consistent, indicating that movement termination may be a controlled variable. Finally, no evidence was found to suggest that visual information was used to amend arm movements early (before peak velocity) in the trajectory.

Journal Article↗

Human Eye Movements During Visually Guided Stepping.

Visually guided locomotion was studied in an experiment in which human subjects (N = 8) had to accurately negotiate a series of irregularly spaced stepping-stones while infrared reflectometry and electrooculography were used to continuously record their eye movements. On average, 68% of saccades made toward the next target of footfall had been completed (visual target capture had occurred) while the foot to be positioned was still on the ground; the remainder were completed in the first 300 ms of the swing phase. The subjects' gaze remained fixed on a target, on average, until 51 ms after making contact with it, with little variation. A greater amount of variation was seen in the timing of trailing footlift relative to visual target capture. Assuming that subjects sampled the visual cues as and when they were required, visual information appeared most useful when the foot to be positioned was still on the ground.

Journal Article↗

Age-related changes in visual tracking.

BACKGROUND: To reassess conflicting findings in earlier studies on the effect of aging on smooth pursuit and saccadic eye movements, we compared visual tracking in a large number of elderly normal subjects aged 75 to 93 years and a group of young adults aged 18 to 43 years. METHODS: Saccades and smooth pursuit were induced by a laser target projected onto a screen. Eye movements were recorded with electrooculography and analyzed with a digital computer. RESULTS: Smooth pursuit gain was significantly decreased at all target velocities in the older subjects, and the difference between young and old increased with increasing target velocity and acceleration. Peak saccade velocity was significantly slower for amplitudes exceeding 20 degrees, and saccadic reaction times were prolonged in older subjects compared with younger subjects. Mean saccade accuracy was not significantly different between age groups. Within tests, variability increased with aging for smooth pursuit, saccadic reaction time, and saccadic accuracy measurements. CONCLUSION: The increased intratest variability in older subjects probably resulted from nonspecific changes in alertness and attention commonly occurring with aging, whereas the decreased gain of smooth pursuit and saccades with increasing stimulus magnitude most likely resulted from age-related neural degeneration in specific visuomotor pathways.

Adolescent↗