A Neonate with Bilateral Vitreous Hemorrhages After Intra-uterine Bowel Infarction Secondary to Volvulus

Vitreous hemorrhages are uncommon in the neonatal period. This article describes a neonatal who had bilateral vitreous hemorrhages after intrauterine bowel infarction.     

Vitreous cytology in asteroid hyalosis and observations on interpretation of cytologic findings in specimens of the posterior (vitreous) compartment of the eye

Cytologic methods have been used in the pathologic investigation of the posterior (vitreous) compartment of the eye in specimens obtained by fine-needle aspiration, as well as by surgical procedures. The vitreous body, which is in a semiliquid gel state, lends itself to pathologic investigation by cytologic methods. We report on a case of reparative eye surgery for complications of previous cataract extraction; vitrectomy was performed for vitreous opacities, which, by cytologic examination, were diagnostic of asteroid hyalosis, a relatively uncommon condition affecting the elderly. The cytologic findings diagnostic of this disease are described. Observations are made on the cytologic findings commonly encountered in specimens obtained from the posterior (vitreous) compartment of the eye.     

A no-moving-parts sensor for the detection of eye fixation using polarised light and retinal birefringence information

Polarised near-infra-red light is reflected from the foveal area in a detectable bow-tie pattern of polarisation states, offering the opportunity for eye tracking. A coaxial optical transducer was developed, consisting of a laser diode, a polariser, a filter, and a photodetector. Several such transducers may be used to interrogate different spots on the retina, thus eliminating the requirement for scanning systems with moving parts. To test the signal quality obtainable, using just one transducer, a test subject was asked to fixate successively on twelve targets located on a circle around the transducer, to simulate the retina’s being interrogated by twelve sensors placed on a 3⁰ diameter circle surrounding the projection of the fovea. The resulting signal is close to the “ideal” sine wave that would have been recorded from a propeller-type birefringence pattern from a human fovea. The transducer can be used in the detection of fixation for medical and other purposes. It does not require calibration, strict restrictions on head position, or head-mounted appliances.     

急性而短暂的精神病性障碍患者的探究性眼球轨迹运动

目的:研究急性而短暂的精神病性障碍(ATPD)患者探究性眼球轨迹运动及其对疾病转归的临床意义。方法:对符合国际疾病和相关健康问题统计分类第十版(ICD-10)诊断标准的来自病房或门诊的34例ATPD患者、33例精神分裂症患者及29例正常对照进行探究性眼球轨迹运动检查并分析眼动参数。三组受试年龄、性别和受教育程度均匹配。用阳性和阴性症状量表(PANSS)评定患者的精神症状。ATPD患者在入组时及入组1个月后各行1次眼动检查,另外两组均行1次眼动检查。对ATPD患者进行随访以了解诊断变化。结果:ATPD患者眼动参数反应性探究分、认知性探究分均低于正常对照(P<0.05),判别分析(discriminant analysis,D分)值高于正常对照。经至少1个月随访,18例ATPD患者改诊为精神分裂症,其中首次D分值为正分占72.22%;这18例患者首次D分值高于正常对照和16例改诊为其他精神障碍者(P<0.05),而与精神分裂症患者差异无统计学意义。结论:急性而短暂的精神病性障碍患者探究性眼球轨迹运动存在异常;判别分析值正分可能为急性而短暂的精神病性障碍转归为精神分裂症提供一种有价值的预测指标。     

Prestretch potentiation of human skeletal muscle during ballistic movement

The conditions associated prior to and during the transition from prestretch to shortering may have considerable influence on the final performance of muscle. In the present study male subjects of good physical condition performed vertical jumps on the force-platform with and without preliminary counter movement. In the counter movement jump (CMJ) the amplitude of the knee bending, velocity of the prestretch and the force attained at end of prestretch were the primary parameters of interest. In addition the coupling time indicating the transition from the eccentric (prestretch) phase to the concentric phase was recorded from the angular displacement and reaction force curves. In the final calculation the mechanical performance parameters of CMJ were always compared with those of the jumps performed without counter movement. The results indicated in general first that CMJ enhanced the average concentric force and average mechanical power by 423 N (66%) and 1158 W (81%), respectively. This potentiation effect was the higher the higher was the force at end of prestretch (p<0.001). Similarly, the prestretch speed (p<0.001) and short coupling time (p<0.01) were associated with enhanced performance during the concentric phase. The average coupling time was 23 ms. The results are interpreted through changes in the prestretch conditions to modify the acto-myosin cross-bridge formation so that the storage and utilization of elastic energy is associated with high prestretch speed, high eccentric force and short coupling time. The role of the reflex potentiation is also suggested as additional enhancement of the final performance.     

Latency of saccades during smooth-pursuit eye movement in man Directional asymmetries

To examine the effects of smooth-pursuit eye movements on the initiation of saccades, their latency was measured when subjects initially fixated or pursued a target. In half of the block of trials, the fixation or pursuit target was extinguished 200 ms before the saccade target was illuminated (gap trials). Reduction of the mean saccade latency in the gap trials (the “gap effect”) was evident even when the subjects were pursuing a moving target, consistent with previous observations. The effect of pursuit direction on saccade latency was also examined. Saccades in the same direction as the preceding pursuit (forward saccades) had shorter latencies than those in the opposite direction (backward saccades). This asymmetry was observed in both the gap and nongap trials. Although the forward-backward asymmetry was much smaller than the “gap effect”, it was statistically significant in six of eight cases. These results suggest that the preparation of saccades is affected by smooth-pursuit eye movements. Received: 2 June 1997 / Accepted: 6 November 1997     

Suppressive effects of a peripheral grating displacement during saccadic eye movement and during fixation

Summary Rapid displacement of a peripheral grating reduced sensitivity to test flashes presented at the center of gaze equally well, whether the displacement was produced by mirror movement during fixation or by saccadic eye movement with the grating stationary. Small 0.5 ° flashes in the retinal periphery were not affected by distant grating displacements, but large (5.0 °) flashes were suppressed. Thus there is a size-selective suppressive mechanism which does not affect small stimuli except at the fovea.This research was supported by NIH (NEI) grant No. 5R01 EY01497 to Dr. Brooks and by NIH (NEI) Postdoctoral Fellowship No. 5F32 EY05 191-03 to Dr. Impelman     

Single unit activity in the frontal eye fields of unanesthetized monkeys during eye and head movement

Summary Single unit activity in the frontal eye field was investigated in unanesthetized monkeys during eye and head movement. Two types of cells (I and II) were found. Type I fired during voluntary saccadic movement occuring in a given direction and also during the fast phase of optokinetic and vestibular nystagmus. Cells of this type were silent during smooth pursuit movement and the slow phase of nystagmus. It was found that the firing pattern of Type I cells was maintained irrespective of head movement.Type II cells fired during smooth pursuit eye movements and the slow phase of nystagmus; these units displayed a steady discharge when the eyes were oriented in a specific position. Also this type of cell maintained its characteristic discharge during head movement. A separate population of frontal eye field cells was found to be exclusively related to head turning.     

Human amygdala activation during rapid eye movements of rapid eye movement sleep: an intracranial study

The amygdaloid complex plays a crucial role in processing emotional signals and in the formation of emotional memories. Neuroimaging studies have shown human amygdala activation during rapid eye movement sleep (REM). Stereotactically implanted electrodes for presurgical evaluation in epileptic patients provide a unique opportunity to directly record amygdala activity. The present study analysed amygdala activity associated with REM sleep eye movements on the millisecond scale. We propose that phasic activation associated with rapid eye movements may provide the amygdala with endogenous excitation during REM sleep. Standard polysomnography and stereo‐electroencephalograph (SEEG) were recorded simultaneously during spontaneous sleep in the left amygdala of four patients. Time–frequency analysis and absolute power of gamma activity were obtained for 250 ms time windows preceding and following eye movement onset in REM sleep, and in spontaneous waking eye movements in the dark. Absolute power of the 44–48 Hz band increased significantly during the 250 ms time window after REM sleep rapid eye movements onset, but not during waking eye movements. Transient activation of the amygdala provides physiological support for the proposed participation of the amygdala in emotional expression, in the emotional content of dreams and for the reactivation and consolidation of emotional memories during REM sleep, as well as for next‐day emotional regulation, and its possible role in the bidirectional interaction between REM sleep and such sleep disorders as nightmares, anxiety and post‐traumatic sleep disorder. These results provide unique, direct evidence of increased activation of the human amygdala time‐locked to REM sleep rapid eye movements.     

Amygdaloid kindling during rapid eye movement (REM) sleep in cats

Development of amygdaloid kindling was analyzed during REM sleep and during wakefulness. Daily evolution of electrographic and behavioral changes was significantly delayed in REM kindled rats. The number of kindling trials required to reach the first generalized convulsive seizure was also significantly increased in comparison with awake kindled animals. Changes in sleep organization were measured under REM kindling conditions. A significant increase in total sleep time and in the percentage of light slow-wave sleep was found during the kindling process. No significant sleep changes were observed in REM-established kindling. REM inhibitory influence over epileptogenesis is discussed.     

The assessment of position of stationary targets perceived during saccadic eye movement

Summary The experiment was performed to establish the accuracy with which visual targets perceived during saccadic eye movement are localised. Subjects were presented with the task of executing saccades of 30° plus amplitude, passing through primary gaze, about the time of peak velocity a 5 ms red flash was presented at some random position (up to 30° left or right of centre) on a horizontal visual display. Subjects were required to indicate the direction in which they thought the flash was localised by fixating in that direction. Observations were made under conditions of prolonged total darkness and in the presence of a contrasting background. Measurement was made of saccade velocity and eye displacement as an index of target positions. Eye displacement was linearly scaled with respect to true target direction. Targets were localised with an average error of 5°–6° although the variance was high. No systematic differences were found between conditions or subjects. Error was unrelated to saccade velocity. It is concluded that during saccadic eye movements the appreciation of target position is maintained with an acceptable degree of accuracy.     

The influence of target distance on eye movement responses during vertical linear motion

Summary Studies of the linear vestibulo-ocular reflex (LVOR) suggest that eye movement responses to linear head motion are rudimentary. This may be due to inadequate control of target distance (D). As D approaches infinity, eye movements are not required to maintain retinal image stability during linear head displacements, but must become increasingly large as D shortens. The LVOR in the presence of visual targets (VLVOR) was tested by recording human vertical eye and head movements during self-generated vertical linear oscillation (averaging 2.7 Hz at peak excursion of 3.2 cm) while subjects alternately fixated targets at D=36, 142, and 424 cm. Response sensitivity rose from 0.10 deg/cm (5.8 deg/s/g) for D=424 cm to 0.65 deg/cm (37.5 deg/s/g) for D=36 cm. Results employing optical manipulations, including spherical lenses to modify accommodation and accomodative convergence, and prisms to modify fusional vergence without altering accommodation, imply that the state of vergence is the most important variable underlying the effect. Trials in darkness (LVOR) and with head-fixed targets (visual suppression of the LVOR) suggest that, while visual following and perhaps mental set influences results, the major proportion of the VLVOR response is driven by vestibular (presumably otolith) inputs.     

The effects of rapid eye movement sleep deprivation during late pregnancy on newborns' sleep

Sleep deprivation during pregnancy is an emerging concern, as it can adversely affect the development of the offspring brain. This study was conducted to evaluate the effects of deprivation of rapid eye movement (REM) sleep during the third term of pregnancy on the sleep–wake profiles of neonates in the Wistar rat model. Sleep–wake patterns were assessed through electrophysiological measures and behavioural observations during postnatal days 1–21 on pups born to REM sleep‐deprived dams and control rats. Pups of REM sleep‐deprived dams had active sleep that was not only markedly higher in percentage during all the days studied, but also had reduced latency during later postnatal days 15–21. Quiet sleep and wake periods were lower. These factors, along with less frequent but longer sleep–wake cycles, indicated maturational delay in the sleep–wake neural networks. The disruption of time‐bound growth of sleep–wake neural networks was substantiated further by the decreased slope of survival plots in the sleep bouts. Examination of altered sleep–wake patterns during early development may provide crucial information concerning deranged neural development in the offspring. This is the first report, to our knowledge, to show that maternal sleep deprivation during pregnancy can delay and impair the development of sleep–wake profile in the offspring.     

Contributions from eye movement potentials to stimulus preceding negativity during anticipation of auditory stimulation

Cognitive anticipation of a stimulus has been associated with an ERP called "stimulus preceding negativity" (SPN). A new auditory delay task without stimulus-related motor activity demonstrated a prefrontal SPN, present during attentive anticipation of sounds with closed eyes, but absent during distraction of attention and during attention with fixed gaze. ERP maxima found near the eyes required examination of eye movement interference, wherefore six monopolar EOG electrodes were included. Similarities between ERPs and potentials evoked by voluntary eye movements with respect to spatial distribution and polarities of amplitudes around the eyes and over the frontal cortex suggested that, in the closed-eyes condition, small involuntary downward eye movements occurred during attentive anticipation of sounds. Analyses of single trials corroborated this interpretation. On this basis it is suggested that the SPN was caused by such eye movements.     

Slow eye movement detection can prevent sleep-related accidents effectively in a simulated driving task

A delayed response caused by sleepiness can result in severe car accidents. Previous studies suggest that slow eye movement (SEM) is a sleep‐onset index related to delayed response. This study was undertaken to verify that SEM detection is effective for preventing sleep‐related accidents. We propose a real‐time detection algorithm of SEM based on feature‐extracted parameters of electrooculogram (EOG), i.e. amplitude and mean velocity of eye movement. In Experiment 1, 12 participants (33.5 ± 7.3 years) performed an auditory detection task with EOG measurement to determine the threshold parameters of the proposed algorithm. Consequently, the valid threshold parameters were determined, respectively, as >5° and <30° s^?1. In Experiment 2, 11 participants (32.8 ± 7.2 years) performed a simulated car‐following task to verify that the SEM detection is effective for preventing sleep‐related accidents. Accidents in the SEM condition were significantly more numerous than in the non‐SEM condition (P < 0.01, one‐way repeated‐measures anova followed by Scheffé’s test). Furthermore, no accident occurred in the SEM condition with a warning generated using the proposed algorithm. Results also demonstrate clearly that the SEM detection can prevent sleep‐related accidents effectively in this simulated driving task.     

Activity of movement sensitive neurons of the cat's tectum opticum during spontaneous eye movements

Summary Activity of tectal movement specific neurons was recorded during spontaneous eye movements in total darkness and in presence of stationary visual stimuli. According to their reactions in presence or absence of stationary visual stimuli tectal units can be divided into four categories:1. Neurons which are silent or discharge independently of eye movements, when the animal stays in total darkness, but which fire in synchrony with eye movements when stationary stimuli are presented. 2. Neurons which remain unaffected when the animal makes eye movements in total darkness or in presence of a stationary pattern. 3. Neurons which fire in synchrony with eye movements in absence and in presence of stationary patterns. In a few of these neurons tested curarization of the animal led to a marked increase of spontaneous activity. 4. Neurons whose spontaneous and stimulus driven discharge is suppressed in synchrony with eye movements when the animal is exposed to total darkness or when it faces stationary patterns     

Chemokine CXCL-1: activity in the vitreous during proliferative vitreoretinopathy

The aim of this study was to investigate CXCL-1 chemokine levels in the vitreous during rhegmatogenous retinal detachment (RRD) with and without proliferative vitreoretinopathy (PVR) and identify possible correlations with clinical parameters (extent and duration or RRD and PVR grade). Vitreous samples from patients with primary RRD with or without PVR were collected and assayed using a double antibody enzyme-linked immunosorbent assay (ELISA). Eleven vitreous samples from organ donors were employed as a control group. CXCL-1 levels were measured in 35 vitreous samples from 35 RRD patients. Mean CXCL-1 levels (64·82 ± 6·47 pg/ml) were significantly higher (P = 0·048) compared to controls. There was a significant positive correlation between CXCL-1 levels and the extent of the detachment (r = 0·794, P = 0·006). Peak CXCL-1 levels coincided with 3+ quadrant RRD, an interim of 29–60 days’ duration and PVR grade B. Increased CXCL-1 levels may be indicative of mild inflammation in the detached retina and the adjacent vitreous. The results of the present study may provide novel insight into the complex interactions taking place during the early and late stages of RRD complicated by PVR.     

Daily rhythm of locomotor activity is abolished during rapid eye movement sleep deprivation in the rat

Applying a modified flowerpot technique, which made it possible to use a test animal as its own control, twenty-four hour cycles of locomotor activity were recorded in eight juvenile male rats on 12/12 hr light/dark (LD) schedule during six days of rapid eye movement (REM) sleep deprivation. It was found that the LD difference in locomotor activity unrelated to feeding was instantaneously abolished during REM sleep deprivation. The daily rhythm of food-directed activity, however, was only gradually attenuated. Due to this equalisation in the light and dark activity the rats gave an impression of hyperactivity during the light hours although the total daily motor output after an initial increase returned close to the baseline value.     

Alpha-band power in the left frontal cortex discriminates the execution of fixed stimulus during saccadic eye movement

Introduction: The saccadic paradigm has been used to investigate specific cortical networks involving attention. The behavioral and electrophysiological investigations of the SEM contribute significantly to the understanding of attentive patterns presented of neurological and psychiatric disorders and sports performance. Objective: The current study aimed to investigate absolute alpha power changes in sensorimotor brain regions and the frontal eye fields during the execution of a saccadic task. Methods: Twelve healthy volunteers (mean age: 26.25; SD: ±4.13) performed a saccadic task while the electroencephalographic signal was simultaneously recorded for the cerebral cortex electrodes. The participants were instructed to follow the LEDs with their eyes, being submitted to two different task conditions: a fixed pattern versus a random pattern. Results: We found a moment main effect for the C3, C4, F3 and F4 electrodes and a condition main effect for the F3 electrode. We also found interaction between factor conditions and frontal electrodes. Conclusions: We conclude that absolute alpha power in the left frontal cortex discriminates the execution of the two stimulus presentation patterns during SEM.