The visual perceptual range of a lizard, <Emphasis Type="Italic">Tiliqua rugosa</Emphasis>

The fragmentation of landscapes produces habitat gaps where the distance between visual landmarks may exceed the perceptual range of a species and impose navigational constraints. We estimated the visual perceptual range of the Australian sleepy lizard, Tiliqua rugosa, by releasing individuals in the centre of a cleared arena in high temperature conditions, with a 0.5-m-high bush placed either 10, 20 or 30 m from the release site. Lizards were more likely to locate those bushes and shelter under them when they were closer, and no lizards found a bush at 30 m. In addition, lizards were less likely to move from the release point when bushes were at 30 m than when they were at the two closer distances. These data suggest that for sleepy lizards the perceptual range for a 0.5-m-high bush is about 20 m. In the uncleared chenopod shrub-land where these lizards live, suitable shelter bushes are an average of 10.5 m from any point in their home range, well within their perceptual range.     

Mechanisms of species divergence through visual adaptation and sexual selection: Perspectives from a cichlid model sys-tem

The theory of ecological speciation suggests that assortative mating evolves most easily when mating preferences are directly linked to ecological traits that are subject to divergent selection. Sensory adaptation can play a major role in this process, because selective mating is often mediated by sexual signals: bright colours, complex song, pheromone blends and so on. When divergent sensory adaptation affects the perception of such signals, mating patterns may change as an immediate consequence. Alternatively, mating preferences can diverge as a result of indirect effects: assortative mating may be promoted by selection against intermediate phenotypes that are maladapted to their (sensory) environment. For Lake Victoria cichlids, the visual envi-ronment constitutes an important selective force that is heterogeneous across geographical and water depth gradients. We investi-gate the direct and indirect effects of this heterogeneity on the evolution of female preferences for alternative male nuptial colours (red and blue) in the genus Pundamilia. Here, we review the current evidence for divergent sensory drive in this system, extract general principles, and discuss future perspectives.     

Effect of latanoprost on intraocular pressure,visual acuity and C-reactive protein

ObjectiveTo investigate the effect of latanoprost on intraocular pressure (IOP), visual acuity and C-reactive protein (CRP) in patients with primary open-angle glaucoma (POAG).MethodsA total of 163 POAG patients (266 eyes) admitted to our hospital from February 2015 to July 2017 were selected and divided into observation group (81 cases, 132 eyes, latanoprost eye drops) and control group (82 cases, 134 eyes, timolol maleate eye drops) according to different treatment plans. The clinical efficacy of the two groups after treatment was evaluated. The IOP, visual acuity and CRP level were compared between the two groups before and after treatment. Then the adverse reactions of the two groups were observed and recorded.ResultsAfter treatment, the total effective rate was 92.59% (75 cases) in the observation group and was 80.49% (66 cases) in the control group, with statistic difference between groups (P < 0.05); The IOP, visual acuity and CRP level between the two groups before treatment showed no statistic difference, the mentioned three indexes of the two groups were significantly improved after treatment, and statistic difference was found before and after treatment (P < 0.05); Moreover, the above three indicators had statistically significant differences between groups after treatment (P < 0.05); The difference of intraocular pressure and visual acuity between the two groups before and after treatment were statistically different (P < 0.05); After treatment, the incidence of adverse reactions in the observation group such as allergy, vomiting, breathlessness and tachycardia were not significantly different from those in the control group (P > 0.05).ConclusionLatanoprost can improve IOP, visual acuity, and CRP levels. It improves eye hemodynamics, and has significant efficacy in treating primary open-angle glaucoma. Also, it has good security.     

Motion parallax contribution to perception of self-motion and depth

The object of this study is to mathematically specify important characteristics of visual flow during translation of the eye for the perception of depth and self-motion. We address various strategies by which the central nervous system may estimate self-motion and depth from motion parallax, using equations for the visual velocity field generated by translation of the eye through space. Our results focus on information provided by the movement and deformation of three-dimensional objects and on local flow behavior around a fixated point. All of these issues are addressed mathematically in terms of definite equations for the optic flow. This formal characterization of the visual information presented to the observer is then considered in parallel with other sensory cues to self-motion in order to see how these contribute to the effective use of visual motion parallax, and how parallactic flow can, conversely, contribute to the sense of self-motion. This article will focus on a central case, for understanding of motion parallax in spacious real-world environments, of monocular visual cues observable during pure horizontal translation of the eye through a stationary environment. We suggest that the global optokinetic stimulus associated with visual motion parallax must converge in significant fashion with vestibular and proprioceptive pathways that carry signals related to self-motion. Suggestions of experiments to test some of the predictions of this study are made.     

How many for dinner? Recruitment and monitoring by glances in capuchins

Group members present physical and physiological differences according to their age, sex or social status, which could generate motivation differences among individuals during travel. In spite of these divergences of interest among individuals, the group succeeds more often than not in making a collective decision about departure time and which direction to take. To reach a consensus decision, animals should exchange information relating to characteristics of group movement through different communication channels. The main purpose of this study is to understand the function of behaviour patterns displayed during movements of white-faced capuchins (Cebus capucinus). We designed experiments in which we provoked collective movements involving a binary choice. During experiments, a video camera recorded the behaviour of each capuchin, which enabled us to determine which individuals displayed a behavioural pattern during travel and how this behaviour influenced the other group members. We found that looking backwards seemed to permit the recruitment of group mates during collective movement. This behaviour also seemed to allow the quantification of the number of followers, since the emitter modified its locomotion speed according to this number. In this preliminary study, we showed that visual behaviour was used to recruit and monitor group mates during collective movements and provided information on mechanisms involved in maintaining cohesion and coordination among group members during travel.     

中国对虾维生素营养的研究:Ⅰ.维生素A对中国对虾生长及视觉器官的影响

本文研究维生素Ａ对中国对虾（Ｐｅｎａｅｕｓ　ｃｈｉｎｅｎｓｉｓ）生长及视觉器官的影响,获得如下结果：１．体长 ４ｃｍ、体重１ｇ小虾对饲料中ＶＡ的最适添加量为 １８,０００ ＩＵ／１００ｇ饲料,体长８ｃｍ,体重７ｇ大虾对饲料 中ＶＡ的最适添加量为１２,０００ ＩＵ／１００ｇ饲料,在ＶＡ最适添加量下,对虾增长、增重最快,饲料系数最 低。２．中国对虾的视网膜电图在暗适应条件下有ｂ、ｃ、ｄ三波,在白、蓝、黄三种光照刺激下,只有Ａ３组 （１２,０００ＩＵ／１００ｇ饲料）其视网膜电位达最高值,即ｂ波振幅达２．４５ｍＶ,ｄ波振幅达３．７ｍＶ,表明ＶＡ 在最适添加量下,视觉反应灵敏,视觉功能正常; ３．ＶＡ最适添加量的 Ａ３组对虾眼组织完整、无畸变, 而ＶＡ含量过高或不足各组,其小眼、视网膜、髓体、Ｘ－器官等都有不同程度的畸变、不完整、干瘪等现 象,表明ＶＡ投喂量不当时,会引起视觉器官的发育障碍或病变。     

A neural network model of attention-modulated neurodynamics

Visual attention appears to modulate cortical neurodynamics and synchronization through various cholinergic mechanisms. In order to study these mechanisms, we have developed a neural network model of visual cortex area V4, based on psychophysical, anatomical and physiological data. With this model, we want to link selective visual information processing to neural circuits within V4, bottom-up sensory input pathways, top-down attention input pathways, and to cholinergic modulation from the prefrontal lobe. We investigate cellular and network mechanisms underlying some recent analytical results from visual attention experimental data. Our model can reproduce the experimental findings that attention to a stimulus causes increased gamma-frequency synchronization in the superficial layers. Computer simulations and STA power analysis also demonstrate different effects of the different cholinergic attention modulation action mechanisms.     

Photoreceptor projection and termination pattern in the lamina of gonodactyloid stomatopods (mantis shrimp)

The apposition compound eyes of gonodactyloid stomatopods are divided into a ventral and a dorsal hemisphere by six equatorial rows of enlarged ommatidia, the mid-band (MB). Whereas the hemispheres are specialized for spatial vision, the MB consists of four dorsal rows of ommatidia specialized for colour vision and two ventral rows specialized for polarization vision. The eight retinula cell axons (RCAs) from each ommatidium project retinotopically onto one corresponding lamina cartridge, so that the three retinal data streams (spatial, colour and polarization) remain anatomically separated. This study investigates whether the retinal specializations are reflected in differences in the RCA arrangement within the corresponding lamina cartridges. We have found that, in all three eye regions, the seven short visual fibres (svfs) formed by retinula cells 1–7 (R1–R7) terminate at two distinct lamina levels, geometrically separating the terminals of photoreceptors sensitive to either orthogonal e-vector directions or different wavelengths of light. This arrangement is required for the establishment of spectral and polarization opponency mechanisms. The long visual fibres (lvfs) of the eighth retinula cells (R8) pass through the lamina and project retinotopically to the distal medulla externa. Differences between the three eye regions exist in the packing of svf terminals and in the branching patterns of the lvfs within the lamina. We hypothesize that the R8 cells of MB rows 1–4 are incorporated into the colour vision system formed by R1–R7, whereas the R8 cells of MB rows 5 and 6 form a separate neural channel from R1 to R7 for polarization processing.This research was supported by the Swiss National Science Foundation (PBSKB-104268/1), the Australian Research Council (LP0214956) and the American Air Force (AOARD/AFOSR) (F62562-03-P-0227).     

Excitatory and inhibitory receptive fields of tectal cells are differentially modified by magnocellular and parvocellular divisions of the pigeon nucleus isthmi

It has been known that magnocellular and parvocellular divisions of the pigeon nucleus isthmi exert excitatory and inhibitory actions on tectal cells, respectively. The present study shows that injection of N-methyl-D-aspartate into the parvocellular division results in an increase in responsive strength and extent of the inhibitory receptive fields, which expand into the excitatory receptive fields of tectal cells. This injection concurrently leads to a decrease in responsiveness and extent of the excitatory fields. On the other hand, injection of acetylcholine into the magnocellular division enhances visual responsiveness, although the excitatory field is not obviously changed in extent. Meanwhile, strength and extent of the inhibitory fields are decreased by acetylcholine. The excitatory and inhibitory fields are reduced in both strength and extent by magnocellular and parvocellular injection of lidocaine, respectively. It suggests that isthmic inputs from both parvocellular and magnocellular divisions converge onto the same tectal cells, and the magnocellular and parvocellular subnuclei can modulate excitatory and inhibitory receptive fields of tectal cells, respectively, with some interactions between both fields. Accepted: 1 March 2000