Su-30飞行员在模拟飞行任务中的眼动指标分析

目的：获取战斗机飞行员在模拟飞行任务中的注意力分配情况和工作负荷的变化,为以后的飞行训练提供技术指导。方法：让十八名SU-30飞行员在模拟飞行器上完成爬升和翻转任务,同时使用眼动仪记录下飞行员的眼动数据,将数据源划分为外景、地平仪、高度表、速度表和综合电子屏显五个区域,并对这五个区域的眼动的数据进行分析对比。结果：在两种任务下,飞行员均在在座舱仪表分配更多的注视点和注视时间;在翻转任务中,飞行员在各个兴趣区的瞳孔直径都小于爬升任务中的直径;扫视幅度随着任务难度的加大而减小。结论：眼动技术可以作为测量飞行员注意力分配的有效方法;不同的任务下飞行员有不同的注意力分配模式,飞行员注意力主要集中在座舱仪表内;翻转任务比爬升任务在仪表上分配了更多的注意力,获取飞行员的注意力分配模式可以为飞行学员训练提供参考。     

用稳态视觉诱发电位研究注意的选择机制

众所周知,注意是一种心理活动,是对外界刺激的一种选择,对人的其它认知活动有一定的调节作用。关于注意的选择机制,有两种不同的理论,一种是早期选择机制,另一种是晚期选择机制。稳态视觉诱发电位是视觉通路对外界刺激的一种物理反应,它的产生过程处于认知的早期阶段,如果它能受到注意的调节,这就支持了注意的早期选择机制。在现有的利用闪光稳态诱发电位对注意的研究中,注意的对象是认知任务,而不是闪光。该实验用两种不同频率的闪光分别做诱发源,对在注意与不注意闪光两种情况下(都没有认知任务)的稳态视觉诱发电位进行研究,发现其明显地受注意调节,而且对不同频率光刺激的调节大小不一样。因此,该实验结果支持了注意的早期选择机制。     

小脑控制不同类型眼动的神经编码机制：从小脑皮层到小脑核团

近年来许多研究发现,小脑作为运动控制的主要脑区,除参与运动控制外也与孤独症、精神分裂症、奖励相关的认知功能和社会行为有关,因此小脑相关研究越来越受到重视。研究小脑参与运动学习和运动控制的神经机制是神经科学中最重要的课题之一。眼睛运动的肌肉协调和生物运动特征比其他类型的运动更简单,这使眼动成为研究小脑在运动控制中作用的理想模型。作为收集外界信息的主要方式之一,视觉对日常生活至关重要。为确保清晰视觉,3种主要类型的眼动（眼跳、平滑追随眼动（SPEM）和注视）需受小脑的精确控制,以确保静止或移动的物体保持在视小凹的中心。异常眼动可导致视力障碍,并可作为诊断各种疾病的临床指标。因此,眼动控制研究具有重要的医学和生物学意义。虽然对小脑皮层和顶核在调节眼动中的作用有基本了解,但眼动动力学编码的确切神经机制,尤其是小脑顶核控制追随眼动和注视的神经机制仍不清楚。本综述总结了目前小脑在运动和认知等方面的主要研究问题与小脑相关研究的潜在应用价值,以及近年来有关小脑控制眼动的相关文献,并深入探讨了利用单细胞记录和线性回归模型分析小脑皮层和顶核同一神经元同时参与控制不同类型的眼动,而不同类型眼动的不同动力学参数编码原则不同。此外,基于检测微眼跳的研究结果,我们讨论了小脑顶核参与控制视觉注视的可能神经机制。最后,讨论了最近技术进步给小脑研究带来的新机遇,为今后与小脑相关的研究和脑控义肢的优化控制（例如通过单独改善运动参数优化义肢控制）提供了新思路。     

听觉选择性注意的可塑性及其神经机制研究

本文旨在研究音乐训练是否能增强基于音高和空间位置的听觉选择性注意力,以及音乐训练对听觉可塑性的神经机制.听觉感知实验中,受试者根据音高差异或空间位置差异,选择两个同时播放的数字之一.听觉认知实验在安静和噪声环境中播放频率分辨率不同的复合音,记录受试者听觉脑干频率跟随响应(frequency-following responses,FFRs).本文提出分析FFR的四种方法,即包络相关频率跟随响应(envelope-related frequency-following response,FFRENV)的短时锁相值、瞬时相位差极性图、相位差均值矢量以及时间细节结构相关频率跟随响应(temporal-fine-structure-related frequency-following response,FFRTFS)的幅度谱信噪比.实验结果表明,在完成基于音高的任务时,受过音乐训练的受试者准确率更高、反应时间更短.外界噪声不影响两组人群在基频(fundamental frequency,F0)的神经元锁相能力,但是显著降低了谐波处的神经元锁相能力.受过音乐训练的受试者的神经元在基频处的锁相能力和谐波处抗噪能力均增强,且其FFRTFS幅度谱信噪比与基于音高的行为学准确率呈正相关.因此,受过音乐训练的受试者其音高选择性注意感知能力的提高取决于认知神经能力的增强,经过音乐训练后,F0处FFRENV的锁相能力、谐波处FFRTFS的抗噪和持续锁相能力以及谐波处FFRTFS幅度谱信噪比均明显增强.音乐训练对听觉选择性注意具有显著的可塑性.     

建立猕猴Go/NoGo视觉分辨任务的方法

在认知神经科学研究中,Go/NoGo模型是一种非常有效的研究方法。在本试验中,以两只猕猴为研究对象,采用Go/NoGo模型,以不同的视觉线索作为刺激来研究相关认知行为。结果表明猕猴能够很快学会Go/NoGo视觉分辨任务,而且对NoGo任务的完成要优于对Go任务的完成。本实验建立了一种有效的猕猴Go/NoGo视觉分辨实验的方法及计算机控制系统,为进一步记录神经元活动建立了良好的基础。     

建立猕猴Go/NoGo视觉分辨任务的方法

在认知神经科学研究中，Go/NoGo模型是一种非常有效的研究方法。在本试验中，以两只猕猴为研究对象，采用Go/NoGo模型，以不同的视觉线索作为刺激来研究相关认知行为。结果表明猕猴能够很快学会Go/NoGo视觉分辨任务，而且对NoGo任务的完成要优于对Go任务的完成。本实验建立了一种有效的猕猴Go/NoGo视觉分辨实验的方法及计算机控制系统， 为进一步记录神经元活动建立了良好的基础。     

老化对视觉注意调控网络的影响

目的 老龄化是日益严重的社会性问题。老年人的认知功能，如注意等，出现了明显的衰退。探究老化过程中视觉注意调控网络的改变有助于理解老年人认知功能衰退的神经机制，并为寻找潜在的干预方式提供理论基础。方法 本研究采用经典的双目标注意任务：被试仅需全程注视屏幕中心的黑十字。黑十字左右两侧13.5°视角度会呈现两个相同的视觉圆点，800~1 200 ms后其中随机一个目标会发生改变或者不变。通过采集该视觉注意任务期间的脑电活动信号，比较青年人与老年人在视觉目标改变和不变两种条件下的大脑活动。结果 实验发现在青年人中，额叶、顶叶和颞叶等脑区的电极记录到的神经电活动特征对视觉目标是否改变存在显著性差别，而老年人的脑活动对该视觉目标改变无显著性变化。此外，还发现该脑网络的变化在青年人和老年人中均存在性别差异。结论 注意任务下老年人脑网络难以对外界视觉信息输入做出及时响应，老化过程伴随视觉注意调控网络（额叶、顶叶和颞叶等）功能的衰退，该脑网络的变化存在性别差异。本研究为老化引起视觉注意调控网络损伤提供了新的证据。     

老化对猕猴中颞视区细胞早期方向选择性的影响

中颞视区(middle temporal area、MT/V5)在视觉运动处理过程中起着重要作用。MT区神经元对物体运动方向具有强选择性,而这种细胞的方向选择性被认为是运动方向知觉的神经基础,且已有实验表明方向选择性由于受到注意影响,而在时间进程上分为2个阶段。该研究组先前的实验发现麻醉猕猴(Rhesus macaque)MT区细胞的方向选择性发生了衰退,但该衰退是整个时间进程上平均的结果,并不能在时间进程上揭示其神经机制。因此,为了进一步探索运动方向感知能力下降的神经机制,该实验采用单细胞技术在麻醉猕猴的MT区研究了在正常老化过程中MT区细胞的早期方向选择性变化(early stage direction selectivity,esDB),结果表明老年猕猴MT区细胞早期方向选择性显著降低,具有强早期方向选择性的细胞显著减少。该结果进一步揭示了MT区细胞方向选择性在早期发生的衰退可能介导了视觉运动感知能力的下降。     

视觉图像辨认眼动中的Top－down信息处理

在视觉图像辨认过程中,眼球不是均匀地扫描全幅图像,而是通过一系列快速的眼球跳动来改变注视点位置,有选择地通过注视停顿来采集图象中的关键信息。通过实验对不同图像刺激时的眼动轨迹进行记录与分析,发现：（１）对于简单的几何图形,眼动注视停顿主要集中在图像中几何特征之处,亦即与周围不同的奇异点上;（２）对复杂图象刺激,眼动注视点位置决定于受试者的已有概念模型及其兴趣所在;（３）对中文单字进行辩认时,其眼动模式也是取决于受试者对该单字的知识（也即概念模型）。以上结果提示,视觉图象辨认主要是通过自上而下（ｔｏｐ－ｄｏｗｎ）的信息处理方式才完成．由中枢控制眼球运动,将注视点落到中枢决定的图形奇点上来,通过注视停顿对中枢认为的关键信息之处进行抽提,以实现辨认。这种处理方式不是只取决于输入的图像信息,也不必对目标图像的每个象素进行处理,而只需对图象中少量的关键信息部位进行重点的检测和处理,从而提高了图象信息处理的能力及效率。     

视觉图像辨认眼动中的Top－down信息处理

在视觉图像辨认过程中,眼球不是均匀地扫描全幅图像,而是通过一系列快速的眼球跳动来改变注视点位置,有选择地通过注视停顿来采集图象中的关键信息。通过实验对不同图像刺激时的眼动轨迹进行记录与分析,发现：（１）对于简单的几何图形,眼动注视停顿主要集中在图像中几何特征之处,亦即与周围不同的奇异点上;（２）对复杂图象刺激,眼动注视点位置决定于受试者的已有概念模型及其兴趣所在;（３）对中文单字进行辩认时,其眼动模式也是取决于受试者对该单字的知识（也即概念模型）。以上结果提示,视觉图象辨认主要是通过自上而下（ｔｏｐ－ｄｏｗｎ）的信息处理方式才完成．由中枢控制眼球运动,将注视点落到中枢决定的图形奇点上来,通过注视停顿对中枢认为的关键信息之处进行抽提,以实现辨认。这种处理方式不是只取决于输入的图像信息,也不必对目标图像的每个象素进行处理,而只需对图象中少量的关键信息部位进行重点的检测和处理,从而提高了图象信息处理的能力及效率。     

Microsaccades counteract visual fading during fixation

Our eyes move continually, even while we fixate our gaze on an object. If fixational eye movements are counteracted, our perception of stationary objects fades completely, due to neural adaptation. Some studies have suggested that fixational microsaccades refresh retinal images, thereby preventing adaptation and fading. However, other studies disagree, and so the role of microsaccades remains unclear. Here, we correlate visibility during fixation to the occurrence of microsaccades. We asked subjects to indicate when Troxler fading of a peripheral target occurs, while simultaneously recording their eye movements with high precision. We found that before a fading period, the probability, rate, and magnitude of microsaccades decreased. Before transitions toward visibility, the probability, rate, and magnitude of microsaccades increased. These results reveal a direct link between suppression of microsaccades and fading and suggest a causal relationship between microsaccade production and target visibility during fixation.     

Fixational Eye Movement Correction of Blink-Induced Gaze Position Errors

Our eyes move continuously. Even when we attempt to fix our gaze, we produce “fixational” eye movements including microsaccades, drift and tremor. The potential role of microsaccades versus drifts in the control of eye position has been debated for decades and remains in question today. Here we set out to determine the corrective functions of microsaccades and drifts on gaze-position errors due to blinks in non-human primates (Macaca mulatta) and humans. Our results show that blinks contribute to the instability of gaze during fixation, and that microsaccades, but not drifts, correct fixation errors introduced by blinks. These findings provide new insights about eye position control during fixation, and indicate a more general role of microsaccades in fixation correction than thought previously.     

Measurement and modeling of peripheral detection and discrimination thresholds

This report describes experimental measurements of threshold contrasts as a function of the angle to the visual axis (peripheral threshold contrasts). The visual tasks consist in detection (perception of presence) and discrimination (perception of a form feature) of simple visual signs during a fixation period realistic observing conditions being chosen. Proceeding from the experimental findings a model for forecasting off-axis threshold contrast functions on different visual conditions is developed based upon spatial frequency filters. Further with the aid of a known model visibility fields are calculated.     

Simultaneous Recordings of Human Microsaccades and Drifts with a Contemporary Video Eye Tracker and the Search Coil Technique

Human eyes move continuously, even during visual fixation. These “fixational eye movements” (FEMs) include microsaccades, intersaccadic drift and oculomotor tremor. Research in human FEMs has grown considerably in the last decade, facilitated by the manufacture of noninvasive, high-resolution/speed video-oculography eye trackers. Due to the small magnitude of FEMs, obtaining reliable data can be challenging, however, and depends critically on the sensitivity and precision of the eye tracking system. Yet, no study has conducted an in-depth comparison of human FEM recordings obtained with the search coil (considered the gold standard for measuring microsaccades and drift) and with contemporary, state-of-the art video trackers. Here we measured human microsaccades and drift simultaneously with the search coil and a popular state-of-the-art video tracker. We found that 95% of microsaccades detected with the search coil were also detected with the video tracker, and 95% of microsaccades detected with video tracking were also detected with the search coil, indicating substantial agreement between the two systems. Peak/mean velocities and main sequence slopes of microsaccades detected with video tracking were significantly higher than those of the same microsaccades detected with the search coil, however. Ocular drift was significantly correlated between the two systems, but drift speeds were higher with video tracking than with the search coil. Overall, our combined results suggest that contemporary video tracking now approaches the search coil for measuring FEMs.     

The Effect of Speed of Processing Training on Microsaccade Amplitude

Older adults experience cognitive deficits that can lead to driving errors and a loss of mobility. Fortunately, some of these deficits can be ameliorated with targeted interventions which improve the speed and accuracy of simultaneous attention to a central and a peripheral stimulus called Speed of Processing training. To date, the mechanisms behind this effective training are unknown. We hypothesized that one potential mechanism underlying this training is a change in distribution of eye movements of different amplitudes. Microsaccades are small amplitude eye movements made when fixating on a stimulus, and are thought to counteract the “visual fading” that occurs when static stimuli are presented. Due to retinal anatomy, larger microsaccadic eye movements are needed to move a peripheral stimulus between receptive fields and counteract visual fading. Alternatively, larger microsaccades may decrease performance due to neural suppression. Because larger microsaccades could aid or hinder peripheral vision, we examine the distribution of microsaccades during stimulus presentation. Our results indicate that there is no statistically significant change in the proportion of large amplitude microsaccades during a Useful Field of View-like task after training in a small sample of older adults. Speed of Processing training does not appear to result in changes in microsaccade amplitude, suggesting that the mechanism underlying Speed of Processing training is unlikely to rely on microsaccades.     

Corollary Discharge Failure in an Oculomotor Task Is Related to Delusional Ideation in Healthy Individuals

Predicting the sensory consequences of saccadic eye movements likely plays a crucial role in planning sequences of saccades and in maintaining visual stability despite saccade-caused retinal displacements. Deficits in predictive activity, such as that afforded by a corollary discharge signal, have been reported in patients with schizophrenia, and may lead to the emergence of positive symptoms, in particular delusions of control and auditory hallucinations. We examined whether a measure of delusional thinking in the general, non-clinical population correlated with measures of predictive activity in two oculomotor tasks. The double-step task measured predictive activity in motor control, and the in-flight displacement task measured predictive activity in trans-saccadic visual perception. Forty-one healthy adults performed both tasks and completed a questionnaire to assess delusional thinking. The quantitative measure of predictive activity we obtained correlated with the tendency towards delusional ideation, but only for the motor task, and not the perceptual task: Individuals with higher levels of delusional thinking showed less self-movement information use in the motor task. Variation of the degree of self-generated movement knowledge as a function of the prevalence of delusional ideation in the normal population strongly supports the idea that corollary discharge deficits measured in schizophrenic patients in previous researches are not due to neuroleptic medication. We also propose that this difference in results between the perceptual and the motor tasks may point to a dissociation between corollary discharge for perception and corollary discharge for action.     

The search operating characteristic as a tool for analyzing performance in dynamic visual search tasks.

A standard data plot for the analysis of eye movement behavior in visual search and related tasks, a Search Operating Characteristic (SOC), is proposed. The SOC plots mean fixation duration (in ms) vs. search span (in items/fixation) for different difficulty levels. It is well specified by a reciprocal power function and this function can be explained with the help of Piéron's law.     

Unveiling functions of the visual cortex using task-specific deep neural networks

The human visual cortex enables visual perception through a cascade of hierarchical computations in cortical regions with distinct functionalities. Here, we introduce an AI-driven approach to discover the functional mapping of the visual cortex. We related human brain responses to scene images measured with functional MRI (fMRI) systematically to a diverse set of deep neural networks (DNNs) optimized to perform different scene perception tasks. We found a structured mapping between DNN tasks and brain regions along the ventral and dorsal visual streams. Low-level visual tasks mapped onto early brain regions, 3-dimensional scene perception tasks mapped onto the dorsal stream, and semantic tasks mapped onto the ventral stream. This mapping was of high fidelity, with more than 60% of the explainable variance in nine key regions being explained. Together, our results provide a novel functional mapping of the human visual cortex and demonstrate the power of the computational approach.     

Visual Saliency Prediction and Evaluation across Different Perceptual Tasks

Saliency maps produced by different algorithms are often evaluated by comparing output to fixated image locations appearing in human eye tracking data. There are challenges in evaluation based on fixation data due to bias in the data. Properties of eye movement patterns that are independent of image content may limit the validity of evaluation results, including spatial bias in fixation data. To address this problem, we present modeling and evaluation results for data derived from different perceptual tasks related to the concept of saliency. We also present a novel approach to benchmarking to deal with some of the challenges posed by spatial bias. The results presented establish the value of alternatives to fixation data to drive improvement and development of models. We also demonstrate an approach to approximate the output of alternative perceptual tasks based on computational saliency and/or eye gaze data. As a whole, this work presents novel benchmarking results and methods, establishes a new performance baseline for perceptual tasks that provide an alternative window into visual saliency, and demonstrates the capacity for saliency to serve in approximating human behaviour for one visual task given data from another.