Electrooculographic and electroretinographic study in the chicken after dopamine and haloperidol

The implication of dopamine in the modulation of the standing potential of the eye was tested in the chicken through an indirect electrooculographic method and direct current electroretinogram (ERG) recording after haloperidol, a mixed D1-D2 antagonist. The standing potential of the eye was reduced within 15 min after intravitreal injection of the antagonist (150 g). This effect is rapidly reversed by an application of dopamine. The fast oscillation was preserved but the light peak was either strongly reduced or abolished. The dark trough showed an apparently normal time course. The intensity-voltage function was studied for the various ERG components. After haloperidol the b-wave and the c-wave were strongly reduced, whereas the a-wave was little affected. Together with previous data obtained with intraocular injections of dopamine, our data suggest the involvement of dopamine in the modulation of the standing potential. They also support the hypothesis that the light peak, which is generated by a photoreceptor-pigment epithelium interaction, is influenced by dopamine or by a related substance. The modulatory effect could also be due to a balance between several neurotransmitter systems.     

讨论人机交互中的眼姿势辨别技术

目的：讨论人机交互中各种眼姿势（眼睛运动模式）的辨别技术。眼姿势的准确辨识是成功实现新型的眼机接口的关键环节之一。方法：根据眼电信号产生的生理机制和采集方法,分析各种眼姿势的特点,包括基本眼动模式（眼睛上移、下移、左移、右移）、眨眼模式、凝视模式等,并据此研究对应的辨识技术。结果：应用阈值估计算法、积分算法、模板匹配算法等可将基本眼动模式、眨眼模式、凝视模式初步辨识出来。结论：对各种眼姿势进行特征分类、准确辨识,为设计眼机接口、实现人机交互提供了基础。     

一种新的基于小波变换的EEG视觉伪信号修正方法

提出了一种在基准EEG信号和视觉信号未知条件下,基于小波阈值去噪的方法来修正EEG信号中出现的视觉伪信号(OA)的新方法。这种方法实现了对原始EEG信号进行平稳小波变换(SW T);对低频系数进行两次阈值去噪;对去噪后的信号进行重构。实验结果表明:这种新方法在基准EEG信号和视觉信号未知条件下能有效去除OA,同时适用于眨眼和眼球运动所产生的伪信号。通过不同方法对采集的信号处理后进行比较,说明该方法的有效性。     

The good, the bad and the neutral: electrophysiological responses to feedback stimuli

The feedback error-related negativity (fERN) is a component of the event-related brain potential elicited in gambling and trial-and-error learning tasks by negative, but not positive, feedback stimuli. Here, we present the results of a series of five experiments that investigated the response of the fERN to the presentation of neutral feedback stimuli. In three of the experiments, the neutral feedback stimuli indicated that the participants did not receive a potential reward nor incur a potential penalty (i.e., they received nothing); and in the remaining two experiments, the neutral feedback stimuli did not convey any meaningful information (i.e., the participants were either successful or unsuccessful on those trials, but the feedback stimuli were uninformative about the outcomes). Across the five experiments, we found that neutral feedback stimuli elicited a fERN about as large as that elicited by negative feedback stimuli. This result is consistent with recent proposals that the evaluative system that produces the fERN classifies outcomes into two categories: those outcomes that indicate that a goal has been satisfied and those that do not.     

Reaction of sleepiness indicators to partial sleep deprivation,time of day and time on task in a driving simulator – the DROWSI project

Studies of driving and sleepiness indicators have mainly focused on prior sleep reduction. The present study sought to identify sleepiness indicators responsive to several potential regulators of sleepiness: sleep loss, time of day (TOD) and time on task (TOT) during simulator driving. Thirteen subjects drove a high‐fidelity moving base simulator in six 1‐h sessions across a 24‐h period, after normal sleep duration (8 h) and after partial sleep deprivation (PSD; 4 h). The results showed clear main effects of TOD (night) and TOT but not for PSD, although the latter strongly interacted with TOD. The most sensitive variable was subjective sleepiness, the standard deviation of lateral position (SDLAT) and measures of eye closure [duration, speed (slow), amplitude (low)]. Measures of electroencephalography and line crossings (LCs) showed only modest responses. For most variables individual differences vastly exceeded those of the fixed effects, except for subjective sleepiness and SDLAT. In a multiple regression analysis, SDLAT, amplitude/peak eye‐lid closing velocity and blink duration predicted subjective sleepiness bouts with a sensitivity and specificity of about 70%, but were mutually redundant. The prediction of LCs gave considerably weaker, but similar results. In summary, SDLAT and eye closure variables could be candidates for use in sleepiness‐monitoring devices. However, individual differences are considerable and there is need for research on how to identify and predict individual differences in susceptibility to sleepiness.     

Behavioral relations of medullary reticular formation cells

The movement correlates of unit activity in medullary reticular formation cells were observed in unrestrained cats. Fifty-four percent of these cells had “laterally asymmetrical” movement relations and 38% had “laterally symmetrical” movement relations. All cells that discharged in relation to active lateral movement of the spinal column discharged preferentially in relation to ipsilateral movements, while all cells responding to passive lateral movement discharged preferentially in relation to contralateral movement. Cells related to movements of the vertebral column in the vertical plane and a small number of units related to facial, laryngeal, paw, and other movements were also found. The specific motor relations of reticular formation cells may explain the findings of previous lesion, stimulation, and recording studies.     

ERG and EOG in progressive paravenous retinochoroidal atrophy

A case of paravenous retinochoroidal atrophy was followed over a period of more than 2 years. Rapid progression of the disease was reflected in the deterioration of visual acuity and fields. Electroretinographic recordings revealed reduced photopic and scotopic amplitudes according to the extent of the retinal lesions. In electro-oculography virtually no slow and no fast light-induced oscillations could be recorded. These results suggest an involvement of the entire retinal pigment epithelium.     

Functional analysis of attention-related unit activity in the reticular formation of the monkey

One hundred ninety-seven units were recorded in the brain stem reticular formation of the rhesus monkey during performance on a fixed foreperiod go-no go task. Phasic unit activity related to the cue stimuli (referred to as type II) was described previously in this region by Pragay et al. (25). Type II units can be differentiated into two subgroups based on the presence or absence of anticipatory activity in the prestimulus interval. We found that the responses of the type II units to the cue stimuli were smaller and more variable when the stimuli were presented passively in a nonperformance condition, which suggests that type II activity in the reticular formation is related to stimulus relevance. The anticipatory type II units also were studied in relation to a set to be ready to receive a relevant stimulus (preparatory attention). Preparatory sets developed easily in disjunctive fixed-interval tasks and are thought to be mediated by the reticular formation. Our results are consistent with the possibility that the anticipatory type II units play a role in directing attention to a stimulus in time.