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At least 1,513 records · Page 84Linked to original sources
PubMed1984

Flash induced nystagmus (FIN) in the rabbit: input-output relations.

Flash-induced nystagmus (FIN) was elicited by monocular flicker-stimulation at 20-40 Hz. It was found more often in albino than in pigmented rabbits. Slow phase velocity (SPV) showed a gradual increase, then a steady-state level in most animals and an after-response after cessation of stimulation. incremental and decremental phase mainly showed an exponential change in SPV. Apparent time constants were in the range of 5-40 sec. Simultaneous recording of both eyes revealed greater velocity and amplitude of both phases of FIN in the stimulated eye. FIN can be specified as a type of nystagmus that is evoked by monocular essentially open-loop stimulation of the crossed ("subcortical") visual pathway. Direction-selective elements in the retina may play a specific role and their predominant orientation gives rise to nystagmus in adducting direction in the flicker-stimulated eye as if it were exposed to optokinetic stimulation in the temporonasal direction.

Animals↗
PubMed1985

Critical flicker fusion and double flash discrimination in different parts of the visual field.

The temporal sensitivity of the visual system was investigated in fifteen healthy subjects by determining the critical flicker fusion frequency (CFF) and the performance in a double flash discrimination (DFD) task. Measurements were obtained using a small test light of 2.5 degrees diameter in the fovea and at eight different perifoveal retinal locations along the horizontal and vertical meridians. Statistically significant differences were found for both the CFF and the DFD task showing a higher temporal sensitivity of the nasal and upper than the temporal and lower retinal areas. The functional significance of the findings is discussed and related to electrophysiological and behavioral data which describe a functional superiority of the upper over the lower hemiretinal system.

Adult↗
PubMed1988

The pattern flash elicited P300-complex (PF-P300): a new method for studying cognitive processes of the brain.

For neurological purposes we developed a new method for eliciting P300-waves: Using two different kinds of checkerboard stimuli that were randomly flashed on a TV screen we obtained, besides the well-known usable primary complex, prominent PF-P300-complexes consisting of a marked negative potential (= N250), the PFP300a and the N400 peaks. These components could be related to different cognitive processes such as floating versus selective sustained attention and stimulus evaluation. N250 especially was shown to be closely related to different degrees of difficulty in visual discrimination. Further, the PFP300 components are test-retest reliable and sex-independent. Since they have relative small interindividual variabilities, we consider the N250- and PFP300a-latencies especially as well as the ascending PFP300a-amplitudes to be appropriate parameters for investigating diseases with cognitive disorders objectively.

Brain↗
PubMed1989

The visual evoked potentials to the light emitting diode compared to the flash and pattern reversal stimulus.

Light-emitting diode (LED), flash (FL) and pattern reversal (PR) stimuli were used to elicit visual evoked potentials (VEPs) in 16 normal subjects (32 eyes) and 39 patients (78 eyes) with signs of visual system abnormality. Latencies and amplitudes (plus standard deviations) of 5 components of each response, correlation coefficients of the normal and abnormal responses and false negatives and positives are presented for the 3 kinds of stimuli. The data show that responses to LED stimuli are very similar to those of FL stimuli and should be useful in the operating room to monitor the visual pathways, if various endogenous factors known to affect late responses can be stabilized.

Adolescent↗
PubMedDate not supplied

P2 latency of the flash visual evoked potential in dementia.

P2 latency of the flash visual evoked potential was found not to be prolonged in 13 demented patients compared to age normative predictions derived from a control group. This finding contrasts with a number of studies of demented patients that found P2 latency to exceed normative data. It was stated that the result of normal latency in dementia can hardly be explained only in terms of the sampling method used in this study (unselected dements) and that the finding is possibly due to the increase in latency across the adult life span in normal aging which was found to be much higher than previously reported.

Aged↗
PubMed1976

Carbamazepine in the treatment of the flashing pain syndrome.

Five patients were seen who described similar rapid shot-like pains that we have called "flashing pain syndrome" and whose pain was relieved by carbamazepine. The pathology of these conditions is not uniform, but the clinical description appears to be specific for an unpleasant condition that will respond dramatically to carbamazepine.

Adult↗
PubMed2005

Targeting the cranial nerve: microradiosurgery for trigeminal neuralgia with CISS and 3D-flash MR imaging sequences.

OBJECT: The authors undertook a study to identify magnetic resonance (MR) imaging techniques that can be used reliably during gamma knife surgery (GKS) to identify the trigeminal nerve, surrounding vasculature, and areas of compression. METHODS: Preoperative visualization of the trigeminal nerve and surrounding vasculature as well as targeting the area of vascular compression may increase the effectiveness of GKS for trigeminal neuralgia. During the past years our gamma knife centers have researched different MR imaging sequences with regard to their ability to visualize cranial nerves and vascular structures. Constructive interference in steady-state (CISS) fusion imaging with three-dimensional gradient echo sequences (3D-Flash) was found to be of greatest value in the authors' 25 most recent patients. In 24 (96%) out of the 25 patients, the fifth cranial nerve, surrounding vessels, and areas of compression could be reliably identified using CISS/3D-Flash. The MR images were acceptable despite patients' history of microvascular decompression, radiofrequency (RF) ablation, or concomitant disease. In one of 25 patients with a history of multiple RF lesions, the visualization was inadequate due to severe trigeminal nerve atrophy. CONCLUSIONS: The CISS/3D-Flash fusion imaging has become the preferred imaging method at the authors' institutions during GKS for trigeminal neuralgia. It affords the best visualization of the trigeminal nerve, surrounding vasculature, and the precise location of vascular compression.

Atrophy↗
PubMedDate not supplied

Complete cryptophthalmos: case report with normal flash-VEP and ERG.

We report an infant with bilateral complete cryptophthalmos as part of Fraser Syndrome. Clinical examination and recordings of the electroretinogram and flash visual evoked potential showed a functional visual pathway at retinal and post-retinal levels. Anatomical considerations and the possible complications of surgery made reconstruction of the lids and palpebral fissures inappropriate.

Abnormalities, Multiple↗
PubMedDate not supplied

The value of flash visual evoked potentials in albinism.

In albinism, the majority of temporal retinal fibers serving the nasal visual field cross at the chiasm and project to the contralateral hemisphere. This misrouting is seen in hemispheric asymmetries present in the visual evoked potential (VEP). Misrouting of retinal fibers was also thought to occur in dissociated vertical deviation, Prader-Willi syndrome, and perhaps carrier states of albinism. However, recent literature is reaching the conclusion we have drawn in our laboratory: only albinism shows VEP hemispheric asymmetries that reverse when the other eye is stimulated. Use of different stimuli, recording conditions, and response criteria among investigators has created some confusion in differentiating what constitutes asymmetry. We conclude that use of a diffuse flash stimulus and a bipolar electrode derivation that compares differences between the left and right occipital hemispheres will clearly differentiate albinism from all other conditions, making it especially useful in a pediatric population.

Adolescent↗
PubMed1993

Flash sterilization and instrument tape--an experimental study.

A letter appearing in the AORN Journal questioned whether flash sterilization is appropriate for instruments coded with color identification tape. The reply stated that porous, colored tape required a longer time to penetrate and sterilize the area beneath, and thus if it should peel off, the zone beneath might not be sterile. This conclusion was, as far as we can determine, reached by intuitive reasoning and not by experimental evidence. Therefore, the following experimental approach was undertaken to test the hypothesis. Spores on discs were placed between the color-code tape and a metal instrument. Exposure to heat (135 degrees C) and time (3 min.) was in a gravity displacement sterilizer. We then determined whether spore kill has been achieved. The test organism was B. stearothermophilus. None of the discs that were in contact with the instruments while being sterilized showed any growth. Thus, it appears that sterility can be achieved on the instrument surfaces that are beneath color-code tape in three minutes.

Equipment Contamination↗
PubMed1999

Formation of tryptophan radicals in irradiated aqueous solutions of hexachloroplatinate(IV): a flash photolysis study.

The oxidation of tryptophan photosensitized by PtCl6(2-) has been investigated in aqueous solutions at different pH using nanosecond laser flash photolysis. Cationic and neutral radicals of tryptophan were detected at pH 2.8 and 8.5, respectively. The generation of the radical was attributed to oxidation by Cl2- that was formed from the homolytic bond cleavage in the excited state of PtCl6(2-). The bimolecular rate constant derived from the kinetics analysis, 2.8 +/- 0.2 x 10(9) M-1 s-1, is in good agreement with the value obtained in earlier pulse radiolysis studies. Both the cationic and neutral radicals decayed by second-order kinetics, consistent with the dimerization process.

Cisplatin↗
PubMed2000

[Negative-type flash electroretinogram].

The authors explain the entity of the negative-type flash electroretinogram (negative ERG), its morphology and origin. They also describe some retinal diseases and syndromes with this type of ERG. On the basis of the literature and own experiences the authors emphasize its diagnostic and prognostic value.

Electroretinography↗
PubMedDate not supplied

Disinfection with flash lamps.

The analysis of published and new data on a pulsed disinfection is presented. It allows the conclusion that the pulsed disinfection mechanism includes both germicidal action of UVC light and a rupture of bacteria due to thermal stress, caused primarily by all UV components of the light pulse. The role of simultaneous cooling and heating of bacteria during a flash lamp pulse has been estimated and a direct detection of such a mechanism is proposed. It is suggested that an optimum pulsed light source for disinfection must have as much percentile content of a broad UV spectrum and a high peak power as is technically justified. Two new applications for pharmaceutics and medicine are suggested.

Disinfection↗
PubMed1999

[Can police car flashing lights induce a risk of encephalographic epileptic discharges and seizures?].

The new police car flashing-light device (930 Heliobe Lightbar) has recently been implicated as potentially epileptogenic. We exposed 30 epileptic patients, 30 nonepileptic patients who suffered from headache and 15 normal volunteers to this light source. All had routine EEGs with standard intermittent photic stimulation, followed by 3-minute stimulation with the Lightbar. In none were either seizures or EEG changes induced. In 1 epileptic spike-and-wave activity induced by standard photic stimulation was enhanced with the Lightbar. We could not confirm that the Lightbar is epileptogenic.

Adult↗
PubMed2000

Can police car colored flash light induce encephalographic discharges and seizures?

AIM: To explore the epileptogenic potential of a newly introduced police car flash light device (930 Heliobe Lightbar). METHODS: A 930 Heliobe Lightbar was installed in the EEG laboratory. Thirty patients with known epilepsy, 30 otherwise healthy subjects with chronic headache, and 15 healthy volunteers were examined. All the subjects signed an informed consent and underwent an EEG during which photostimulation was performed first with the standard stroboscope, and later with the Police lightbar. RESULTS: In all 75 examinees the lightbar did not induce clinical or electrographic seizures. In a single patient with epilepsy, the lightbar enhanced epileptiform activity induced by standard photic stimulation. CONCLUSION: The new Police light bar was found to be non-epileptogenic.

Adult↗
PubMed1975

Electrical response of the eye at varying intervals following an adapting flash exposure.

Electroretinograms (ERG) were recorded at varying intervals following an adapting flash exposure. Both amplitude and latency variations are exhibited for short interflash intervals. The ERG following the longer interflash intervals are not significantly different from the dark-adapted ERG. The relationship between the electrophysiological and psychophysical data is discussed.

Adaptation, Ocular↗
PubMed2000

[The effect of prenatal exposure to cadmium on flash visual evoked potentials in rat offspring before and after injection of norepinephrine into the lateral brain ventricle].

AIM: It is known that norepinephrine (NE) in low doses increases the amplitude of flash visual evoked potential (FVEP). The purpose of this paper was to find out if cadmium (Cd) intoxication changes the NE effect on FVEP. MATERIAL AND METHODS: 18 Wistar albino rats were divided into 3 groups: 6 received 5 ppm, next 6 received 50 ppm cadmium in drinking water since time of conception and during 21 days after delivery and 6 as a control group received tap water only. Newborns were examined when they were 3 to 6 months old. FVEP were recorded before and after injection of 10 microliters saline and then NE into the right lateral brain ventricle. Two doses of NE 25 and 50 nmols were used. Amplitudes of the first deep negative wave (N1) and the next positive one (P2) were measured from isoelectric line to peaks. For statistic analysis the Student t-test was performed with statistical significance by p < 0.05. RESULTS: The prolongation of N1 and P2 latencies of FVEP was observed in all groups after both doses of NE, the differences were statistically significant after doses of 25 nmols NE. The amplitude of N1 increased after NE in all groups, in the control one till 205-225% and 143-151% in Cd groups. The amplitude of P2 in control group was higher (109-113%) after NE compared to initial value (100%). Cadmium caused the decrease (of 56-90%) after both doses of NE. The differences of amplitudes were statistically significant. The prenatal treatment by cadmium caused the lower sensitivity of FVEP to NE.

Administration, Oral↗