A Geometrical Approach to Human Saccade Simulation.

The patterns of optic flow seen during self-motion can be used to determine the direction of one's own heading. Tracking eye movements which typically occur during everyday life alter this task since they add further retinal image motion and (predictably) distort the retinal flow pattern. Humans employ both visual and nonvisual (extraretinal) information to solve a heading task in such case. Likewise, it has been shown that neurons in the monkey medial superior temporal area (area MST) use both signals during the processing of self-motion information. In this article we report that neurons in the macaque ventral intraparietal area (area VIP) use visual information derived from the distorted flow patterns to encode heading during (simulated) eye movements. We recorded responses of VIP neurons to simple radial flow fields and to distorted flow fields that simulated self-motion plus eye movements. In 59% of the cases, cell responses compensated for the distortion and kept the same heading selectivity irrespective of different simulated eye movements. In addition, response modulations during real compared with simulated eye movements were smaller, being consistent with reafferent signaling involved in the processing of the visual consequences of eye movements in area VIP. We conclude that the motion selectivities found in area VIP, like those in area MST, provide a way to successfully analyze and use flow fields during self-motion and simultaneous tracking movements.

Estimating heading during real and simulated eye movements

Relationship between eye acceleration and retinal image velocity during foveal smooth pursuit in man and monkey.

When a single light cue is given in the visual field, our eyes orient towards it with an average latency of 200ms. If a second cue is presented at or around the time of the response to the first, a secondary eye movement occurs that represents a reorientation to the new target. While studies have shown that eye movement latencies to 'single-step' targets may or may not be lengthened with age, secondary eye movements (during 'double-step' displacements) are significantly delayed with increasing age. The aim of this study was to investigate whether the postural challenge posed simply by standing (as opposed to sitting) results in significantly longer eye movement latencies in older adults compared to the young. Ten young (<35years) and 10 older healthy adults (>65years) participated in the study. They were required to fixate upon a central target and move their eyes in response to 2 types of stimuli: (1) a single-step perturbation of target position either 15° to the right or left and (2) a double-step target displacement incorporating an initial target jump to the right or left by 15°, followed after 200ms, by a shift of target position to the opposite side (e.g. +15° then -15°). All target displacement conditions were executed in sit and stand positions with the participant at the same distance from the targets. Eye movements were recorded using electro-oculography. Older adults did not show significantly longer eye movement latencies than the younger adults for single-step target displacements, and postural configuration (stand compared to sit) had no effect upon latencies for either group. We categorised double-step trials into those during which the second light changed after or before the onset of the eye shift to the first light. For the former category, young participants showed faster secondary eye shifts to the second light in the standing position, while the older adults did not. For the latter category of double-step trial, young participants showed no significant difference between sit and stand secondary eye movement latencies, but older adults were significantly longer standing compared to sitting. The older adults were significantly longer than the younger adults across both postural conditions, regardless of when the second light change occurred during the eye shift to the first light. We suggest that older adults require greater time and perhaps attentional processes to execute eye movements to unexpected changes in target position when faced with the need to maintain standing balance.

The sarcomere is the major structural and functional unit of striated muscle. Approximately 65 different proteins have been associated with the sarcomere, and their exact composition defines the speed, endurance, and biology of each individual muscle. Past analyses relied heavily on electrophoretic and immunohistochemical techniques, which only allow the analysis of a small fraction of proteins at a time. Here we introduce a quantitative label-free, shotgun proteomics approach to differentially quantitate sarcomeric proteins from microgram quantities of muscle tissue in a fast and reliable manner by liquid chromatography and mass spectrometry. The high sequence similarity of some sarcomeric proteins poses a problem for shotgun proteomics because of limitations in subsequent database search algorithms in the exclusive assignment of peptides to specific isoforms. Therefore multiple sequence alignments were generated to improve the identification of isoform specific peptides. This methodology was used to compare the sarcomeric proteome of the extraocular muscle allotype to limb muscle. Extraocular muscles are a unique group of highly specialized muscles with distinct biochemical, physiological, and pathological properties. We were able to quantitate 40 sarcomeric proteins; although the basic sarcomeric proteins in extraocular muscle are similar to those in limb muscle, key proteins stabilizing the connection of the Z-bands to thin filaments and the costamere are augmented in extraocular muscle and may represent an adaptation to the eccentric contractions known to normally occur during eye movements. Furthermore, a number of changes are seen that closely relate to the unique nature of extraocular muscle.

Validating and improving the correction of ocular artifacts in electro-encephalography

Proprioceptive role for palisade endings in extraocular muscles: Evidence from the Jendrassik Maneuver

Objective To study the clinical value of orbital magnetic resonance imaging(MRI) in diagnosis and making a judgment about the curative effect of glucocorticoid in patients with Graves' ophthalmopathy(GO). Methods A total of 106 patients with GO were divided into active GO group or inactive GO group according to whether clinical activity score(CAS)≥3 or not, respectively. T2 relaxation times(T2RTs)(ms) and areas(mm2) of four extra-ocular muscles (EOMs) (superior, inferior, medial, and lateral rectus) were directly measured by MRI T2-Mapping. Correlation analysis of T2RTs and areas with eyeball motility, diplopia, exophthalmus, visual acuity and intraocular pressure(IOP) were also performed. The T2RTs and areas of EOMs before and after intravenous methylprednisolone(iv MP) pulse therapy were recorded, respectively. Results The mean T2RTs(88.9±13.8) and mean areas(58.1±23.8) of EOMs in active GO were significantly greater than those in inactive GO(80.6±10.0 and 46.2±18.6, respectively), bing both significantly greater than those in volunteers with normal eyes(76.2±4.7 and 30.3±6.1, respectively)(P<0.01). Maximal T2RTs and maximal areas of EOMs showed significant positive correlation(P<0.01), and both were positively correlated weakly with CAS, reduced movement of eyeball, diplopia, exophthalmus and loss of visual acuity(P<0.01). On the contrary, maximal T2RTs and maximal areas of EOMs showed negative correlation or no correlation with spontaneous retrobulbar pain, painful eye movement, redness of eyelids and abnormal IOP. Even if 1≤CAS<3, ophthalmic symptoms and signs also showed a positive responses to iv MP in patients with moderate to severe GO as long as prolonged T2RTs occurred at least in one of EOMs. The maximal T2RTs, maximal areas, mean T2RTs and mean areas of EOMs were significantly decreased at the end of iv MP treatment, meanwhile ophthalmic symptoms and signs were obviously improved. Conclusions Prolonged T2RTs, especially accompanied by enlarged area on the identical EOMs is an remarkable symbols of acute inflamed muscles. The findings suggested that the use of prolonged T2RTs can improve diagnostic sensitivity and predict the curative effect of iv MP in patients with moderate to severe GO and CAS≥1. (Chin J Endocrinol Metab, 2015, 31: 327-332) Key words: Graves' ophthalmopathy; Magnetic resonance imaging; Methylprednisolone

The oculomotor organization of two elasmobranch species, smooth dogfish (Mustelus canis) and little skate (Raja erinacea), was studied by investigating the extraocular muscle apparatus and the oculomotor motoneuron distribution. The macroscopic appearance of the eye muscles was similar to any lateral-eyed vertebrate species (e.g., goldfish, rabbit). The size of extraocular muscles was expressed by counting single muscle fibers and comparing cross-sectional areas of the extraocular muscles. There were significant differences in the number of fibers in the six extraocular muscles in dogfish, but not in skate. Fiber sizes varied considerably; thus, the number of fibers did not relate to cross-sectional areas. In the dogfish, no one pair of agonist-antagonist extraocular muscles was larger than the others, suggesting that there was no preference for eye movements in a particular plane of space. However, the lateral rectus was more than twice the size of most of the other muscles. In the skate, cross-sectional areas of the horizontal eye muscles were smaller than those of the vertical eye movers. This may indicate a reduced utilization of horizontal eye muscles, which may reflect the bottom-dwelling habitat and mode of locomotion of the skate. The distribution of the extraocular motoneurons was determined by injecting horseradish peroxidase (HRP) into single eye muscles. Medial rectus, superior rectus, and superior oblique motoneuron populations were located contralateral to their respective muscles. Lateral rectus, inferior rectus, and inferior oblique motoneurons were located ipsilateral to their muscles. This distribution is in contrast to almost all other vertebrates studied thus far, where medial rectus motoneurons are located ipsilateral to the muscle which they innervate. The oculomotor arrangement in elasmobranchs is likely to have consequences for the circuitry responsible for the production of conjugate compensatory eye movements in the horizontal plane. We hypothesize that, in contrast to other vertebrates, the basic elasmobranch vestibulo-ocular reflex pathway consists of three identically structured three-neuron-arcs connecting the three semicircular canals to their respective extraocular muscles. This innervation pattern may constitute a special feature of the elasmobranch brain or a phylogenetically older arrangement of eye movement pathways.

Long-term adaptive changes in primate vestibuloocular reflex. III. Electrophysiological observations in flocculus of normal monkeys.

Movements of the head and eye which, together, result in changes in the direction of gaze are linked in a number of species, including man, and eye position is known to affect the activity of neck muscles. This head-eye linkage has generally been ascribed to modification of neck muscle activity by internal estimates of eye position derived from motor commands. We have recently shown that afferent signals from stretch receptors in the extraocular muscles are involved in the moment-to-moment control of eye movements during the vestibuloocular reflex (VOR). We have now studied the interactions between head and eye movements by recording the electromyographic activity of several neck muscles during horizontal (yaw) or frontal (roll tilt) vestibular stimulation. Such a stimulus evokes a VOR in the eyes and a vestibulocollic reflex (VCR) in neck muscles. Imposing movements on one eye at saccadic velocities produced considerable inhibition of the VCR response of a number of neck muscles. The magnitude of these effects was dependent on the parameters of the imposed eye movement. Thus systematic changes were seen when the amplitude, velocity or direction of eye movement was varied. Movement of the eye in the opposite direction to that produced by a normal VOR produced a large inhibition of the VCR response, whereas movements in the same direction as the VOR produced only modest inhibition of the VCR response of the neck muscles tested. Slow, sinusoidal, imposed eye movements that mimicked the slow phase of the VOR produced changes in the gain of the VCR response which appear to correct for errors in the imposed eye velocity and thus tend to maintain the direction of gaze. The results show that changes in eye position have striking effects on the electromyographic activity of neck muscles during the VCR, and strongly suggest that extraocular muscle afferent signals are involved in head-eye coordination.

To solve the problem of user visual attention distribution and spatial misalignment of interface elements in current user interface layout design due to reliance on subjective experience, this paper proposes an optimization method for fashion brand e-commerce user interface design that uses eye tracking simulation and integrates brand characteristics. This paper builds a fashion-specific visual behavior database through multimodal eye movement data collection, and uses the spatiotemporal attention mechanism of the Transformer-XL (Transformer with Extra Long Context) model to predict the gaze hotspots and scanning paths of users in dynamic tasks; then, this paper designs a multi-agent reinforcement learning optimizer, encodes aesthetic rules such as brand logo size and main color ratio as hard constraints, and generates an interface space distribution plan through element competition-collaboration game; finally, this paper develops a real-time interactive prototype based on the Unity engine to achieve dynamic layout closed-loop optimization driven by the collaborative efforts of brand constraints and eye movement simulation heat maps. Experimental results show that this method reduces the task completion time by 32% in the optimization of the light luxury clothing homepage, the overlap between the simulated and real eye movement hot spots reaches 88%, and the brand consistency score increases by 46% (from 3.2 to 4.7), significantly reducing the user's cognitive load and improving the user experience. The conclusion confirms that by integrating eye movement behavior quantification with brand characteristics, it is possible to break through the traditional design's reliance on static aesthetics, provide a “cognitive adaptation-brand expression” dual-goal collaborative intelligent design paradigm for fashion interfaces, and promote the simultaneous improvement of user conversion rate and brand value.

After control studies, using electrodes permanently implanted in the central visual system, squirrel monkeys and macaques were in most instances blinded by acute glaucoma. This permitted subsequent observation of eye movements. Ocular nystagmus developed in all cases. Beginning immediately upon recovery from anesthesia, and persisting for at least 1 year, the EEG of the striate cortex was characterized by totally flat periods up to several seconds in duration which were ended abruptly by a sharp "spike" trailed in turn by a ragged high voltage, slow pattern for another second or two. The great majority of these "spikes" from the blind striate cortex occurred within 60-200 msec after a saccadic eye movement, made either in nystagmus or attempted fixation. They were not dependent upon proprioception from the extraocular muscles. It is suggested that they represent a "corollary discharge" for movement of the eyes. The blind striate cortex was judged to be hyperexcitable on the basis of these saccade-associated "spikes", not often observable in intact monkeys, and from the increase both in response evoked by electrical stimulation of optic radiation and amplitude of the EEG in sleep.

Terrestrial navigation naturally involves translations within the horizontal plane and eye rotations about a vertical (yaw) axis to track and fixate targets of interest. Neurons in the macaque ventral intraparietal (VIP) area are known to represent heading (the direction of self-translation) from optic flow in a manner that is tolerant to rotational visual cues generated during pursuit eye movements. Previous studies have also reported that eye rotations modulate the response gain of heading tuning curves in VIP neurons. We tested the hypothesis that VIP neurons simultaneously represent both heading and horizontal (yaw) eye rotation velocity by measuring heading tuning curves for a range of rotational velocities of either real or simulated eye movements. Three findings support the hypothesis of a joint representation. First, we show that rotation velocity selectivity based on gain modulations of visual heading tuning is similar to that measured during pure rotations. Second, gain modulations of heading tuning are similar for self-generated eye rotations and visually simulated rotations, indicating that the representation of rotation velocity in VIP is multimodal, driven by both visual and extraretinal signals. Third, we show that roughly one-half of VIP neurons jointly represent heading and rotation velocity in a multiplicatively separable manner. These results provide the first evidence, to our knowledge, for a joint representation of translation direction and rotation velocity in parietal cortex and show that rotation velocity can be represented based on visual cues, even in the absence of efference copy signals.

To address the problem of low classification accuracy in existing bioradar sleep staging technology caused by the use of indirect physiological features, research on bioradar sleep eye movement detection is conducted. A synchronous acquisition platform for millimeter-wave bioradar and electrooculogram (EOG)/polysomnography (PSG) is established. Simulated eye movement experiments and real sleep experiments are carried out respectively. In the simulated eye movement experiments, the time-domain cross-correlation coefficient between the eye movement signals detected by the bioradar and the EOG signals exceeds 0.90. The error in the dominant frequency within the frequency domain is less than 0.05 Hz. In the real sleep experiments, eye movement signals consistent with EOG are also detected by the bioradar. These signals exhibit explosive characteristics in the rapid eye movement period, intermittent smooth fluctuation characteristics in the light sleep period, and stable low-amplitude fluctuation characteristics in the deep sleep period. The experimental results indicate that the bioradar can effectively detect and distinguish three typical sleep eye movement events: rapid eye movement, slow eye movement, and no significant eye movement. This provides a new technical approach for bioradar sleep staging, which holds promise for further improving staging accuracy.