Model parameters of the smooth pursuit eye movement system with electrooculogram

The visual pursuit test is a method that collects and analyzes the characteristics of pursuit eye movements and examines the function of the eye movement system. This paper analyzes the model parameters of the smooth pursuit eye movement system in order to explore a method for improving the analysis. The input-output relationship of the smooth pursuit system can be expressed by a quasilinear model. We compute the model parameters (gain, phase, spectral purity, cross covariance) by digital signal processing. Eye movement is recorded by electrooculogram. Both eyes are tested individually. The visual target moves at frequencies of 0.2, 0.4, 0.8, 1.2, and 1.6 Hz. Ranges are gain, 1.01 to 0.70; phase, -0.1 ° to -66 °; spectral purity, 0.97 to 0.70; and cross covariance, 0.99 to 0.26. We tested 40 normal subjects as well as patients with ataxia (8), vertigo (18), and ophthalmoplegia (9). The oculomotor system of normal subjects functions as a linear system in the performance of this test at 0.2 to 0.8 Hz. The spectral purity dropped to about 0.70 at 1.6 Hz. The variability of all measures increases greatly at 1.6 Hz, which indicates that this target motion exceeds the tracking ability of many normal subjects and that the oculomotor system of normal subjects functions as a nonlinear system in this condition. Statistical tests show no significant differences between sex, age, and the two eyes. The model parameters tentatively proved effective in clinical application.     

Quantitative analysis of the suppressive effect on the light rise of the hypertonic solution

We previously reported the hyperosmolarity response (a decrease of the ocular standing potential by hyperosmolarity) as a new clinical test of the retinal pigment epithelium (RPE) activity. In the present study a hypertonic solution (Fructmanit, 1.4 × 10³ m0sm/1) was intravenously injected for 20 min in proportion to a subject's total blood volume (TBV). At the injection speed of 5, 10, and 15% of the subjects' TBV per hour the mean amplitude of the hyperosmolarity response in normal subjects was 19.7, 30.1 and 36.4% respectively. The amplitude of the hyperosmolarity response depends on the logarithm of the dose of the hypertonic solution within the range of the dose tested.We previously found that hyperosmolarity suppresses the light rise. The present study investigated this suppressive effect in a quantitative manner. The light rise (a full-field illumination of 1.2 × 10³ cdl/m²) was dose-dependently suppressed by Fructmanit. The mean of the light rise to dark trough ratio in normal subjects was 1.81 with no osmotic stress, and 1.64, 1.41 and 1.29 respectively at the injection speeds of 5, 10, and 15%. The suppression of the light rise by hyperosmolarity is compatible with the view that the hyperosmolarity response and the light rise share the basal membrane of the RPE as the main site of their generation.     

Macular disease in related rhesus monkeys

During (January) 1986–(May) 1988, we examined 272 eyes in 136 rhesus monkeys in the closed Cayo Santiago colony of the Caribbean Primate Research Center of the University of Puerto Rico. Seventy-eight eyes were less than 10 years of age. One hundred and ninety-four were aged 10–28 years. The fundi were examined and photographed. Fluorescein angiography was performed in some eyes. Selected cases were evaluated for acuity loss by recording of pattern-evoked retinal and cortical signals. Light and electron microscopy were used to evaluate the pigment epithelium of some animals. Thirty-eight percent of all eyes had posterior pole drusen. Incidence was highly age-related. When late-stage lesions were found, we did not see neovascularization, but late hyperfluorescence was consistent with degenerative scarring and atrophy. Electrophysiology demonstrated moderately reduced acuity in the presence of numerous macular drusen. Electrooculograms were low normal. Histopathology showed changes identical to those reported in human age-related macular degeneration. No eyes less than 10 years of age had confluent drusen or disciform-like lesions. The incidence of drusen in samples of some social groups was much higher than others.     

不同类型儿童弱视的视觉眼电图研究

目的：探讨不同类型弱视在视网膜水平的改变。方法：对４种类型的弱视儿童８６例分别进行ＶＥＯＧ测试,并与正常对照组进行比较分析。结果：形觉剥夺性弱视组的光峰电位、电势差值和Ａｒｄｅｎ比明显偏高;屈光参差性弱视组光峰电位偏低,光峰时间延长;屈光不正性弱视组中,近视屈光状态者暗谷电位增大,Ａｒｄｅｎ比与Ｇｌｉｅｍ比偏低,远视屈光状态者则无明显变化;斜视性弱视组各参数未见明显差异。结论：提示在视网膜水平不同     

Bestrophin 1 – Phenotypes and Functional Aspects in Bestrophinopathies

This is to review the current state of knowledge on the functional and clinical aspects of bestrophin 1, a prominent member of a family of proteins involved in the control and properties of the light peak of the EOG. Initially human bestrophin 1 gene (BEST1) mutations were identified to underlie Best vitelliform macular dystrophy (VMD), a dominantly inherited, juvenile-onset form of macular degeneration. In the recent past the phenotypical spectrum of retinal disorders associated with BEST1 mutations has been extended and the term bestrophinopathies was coined. The physiological role of bestrophin 1 is still not completely understood but has been linked to the generation of a transepithelial chloride current by controlling voltage-dependent calcium channels (VDCC). Dysfunction of bestrophin 1 may result in abnormal ion and fluid transport by the retinal pigment epithelium (RPE) disturbing and even disrupting direct interactions between the RPE and the photoreceptors.     

Attention bias in earthquake-exposed survivors: An event-related potential study

The Chinese Wenchuan earthquake, which happened on the 28th of May in 2008, may leave deep invisible scars in individuals. China has a large number of children and adolescents, who tend to be most vulnerable because they are in an early stage of human development and possible post-traumatic psychological distress may have a life-long consequence. Trauma survivors without post-traumatic stress disorder (PTSD) have received little attention in previous studies, especially in event-related potential (ERP) studies. We compared the attention bias to threat stimuli between the earthquake-exposed group and the control group in a masked version of the dot probe task. The target probe presented at the same space location consistent with earthquake-related words was the congruent trial, while in the space location of neutral words was the incongruent trial. Thirteen earthquake-exposed middle school students without PTSD and 13 matched controls were included in this investigation. The earthquake-exposed group showed significantly faster RTs to congruent trials than to incongruent trials. The earthquake-exposed group produced significantly shorter C1 and P1 latencies and larger C1, P1 and P2 amplitudes than the control group. In particular, enhanced P1 amplitude to threat stimuli was observed in the earthquake-exposed group. These findings are in agreement with the prediction that earthquake-exposed survivors have an attention bias to threat stimuli. The traumatic event had a much greater effect on earthquake-exposed survivors even if they showed no PTSD symptoms than individuals in the controls. These results will provide neurobiological evidences for effective intervention and prevention to post-traumatic mental problems.     

基于眼电的阅读状态检测研究

目的阅读是一种重要的认知过程,可通过眼动检测实现观测。基于眼电的阅读检测算法可应用于不同的阅读行为和注意力水平的自动检测。方法通过提取阅读时水平眼电信号的特征以有效识别阅读活动。首先使用数学形态学对原始水平眼电信号进行平滑处理,去除眨眼和肌电等干扰。平滑后的眼电信号进行差分处理,然后提取出阅读时的水平眼电信号的特征,进行识别分类,从而判断出受试的阅读情况,并与实际的阅读状态进行比较。结果对阅读状态和非阅读状态时间段的分析结果显示,数学形态学和阈值法相结合的方法对眨眼和肌电等噪声的抗干扰能力较强,可有效识别出阅读活动,平均检测率为75％。结论数学形态学和特征提取相结合的方法能较好地提取出眼球的活动信息,应用于日常的阅读活动识别中。     

Types of gaze movement: Variable interactions of eye and head movements

The patterns of coordinated eye-head movement in gaze shift are influenced by preconditions of the experimental protocol, such as the predictability and amplitude of the stimulus and the subject's endeavor to move as instructed, either naturally or as fast as possible. Gaze-shift movements fall into four distinct types with respect to eye-head latency, each one involving particular gaze-shift errors and head acceleration trajectories.     

Microinjection of neostigmine into the pontine reticular formation of the mouse: further evaluation of a proposed REM sleep enhancement technique

Microinjections of cholinergic agonists into the pontine reticular formation (PRF) powerfully induce rapid eye movement sleep (REMS) in cats but have comparatively weaker effects in rats. Recently, the cholinomimetic neostigmine has been reported to strongly enhance REMS following microinjection into the PRF of the mouse. That study used behavioral assessments of locomotion in lieu of electrophysiological measures of muscle tone to identify REMS. We sought to confirm that the behavioral state induced in mice by PRF injections of neostigmine meets standard electroencephalogram (EEG) and electromyogram (EMG) criteria for defining REMS. Cortical EEG, nuchal muscle EMG, and PGO waves were recorded from male C57BL/6N mice with chronic indwelling cannulae for the delivery of neostigmine to the PRF. Recordings were made during midday following injections of neostigmine (8.8 mM, 50 nl), 2 h after lights on (LD 12:12). Neostigmine induced a behavioral state characterized by low amplitude, highly desynchronized cortical EEG with little theta, no PGO waves, and a sustained high muscle tone. Behavioral states meeting standard criteria for slow-wave sleep (SWS) and REMS were significantly suppressed compared to baseline recordings, and REMS onset was delayed by 3 h. Consistent with earlier reports, neostigmine did strongly suppress locomotor activity in open field tests and in the home cage. Due to the failure to meet criteria for defining REMS, we conclude that neostigmine microinjection into the PRF of the mouse induces an abnormal waking state rather than REMS.     

Assessing hydroxychloroquine toxicity by the multifocal ERG

Twenty patients on Plaquenil treatment were evaluated for retinal toxicity using the (EOG) and the mfERG. Group 1 comprises 15 patients (30 eyes) with normal EOG. From these patients 11 (22 eyes) showed normal RRD of mfERG in area 1 and area 2. The rest four patients (8 eyes) the RRD were reduced. Six months after interruption of HC, the mfERG improved in three cases. Group 2 comprises 5 patients (10 eyes) with subnormal EOG. Four (8 eyes) of these showed a decrease of RRD of the mfERG in area 1 and 2. In the rest one (2 eyes) the RRD were normal. Six months after interruption of HC the mfERG and the EOG improved in 2 cases. These results postulate that the mfERG may be used as an alternative method, perhaps more sensitive, for the detection of the HC retinopathy and the follow up of the patients on hydroxychloroquine.