Hierarchical Visual Attention Model for Saliency Detection Inspired by Avian Visual Pathways

Visual attention is a mechanism that enables the visual system to detect potentially important objects in complex environment. Most computational visual attention models are designed with inspirations from mammalian visual systems.However, electrophysiological and behavioral evidences indicate that avian species are animals with high visual capability that can process complex information accurately in real time. Therefore,the visual system of the avian species, especially the nuclei related to the visual attention mechanism, are investigated in this paper. Afterwards, a hierarchical visual attention model is proposed for saliency detection. The optic tectum neuron responses are computed and the self-information is used to compute primary saliency maps in the first hierarchy. The "winner-takeall" network in the tecto-isthmal projection is simulated and final saliency maps are estimated with the regularized random walks ranking in the second hierarchy. Comparison results verify that the proposed model, which can define the focus of attention accurately, outperforms several state-of-the-art models.This study provides insights into the relationship between the visual attention mechanism and the avian visual pathways. The computational visual attention model may reveal the underlying neural mechanism of the nuclei for biological visual attention.

Visual pathways involvement in clinically isolated syndrome in children

AIM: To investigate extent and nature of visual pathways involvement in children with clinically isolated syndrome(CIS).METHODS: Forty-seven patients(age 11-17y) with CIS, which later proved to be multiple sclerosis(MS)onset, and 30 controls underwent visual evoked potentials(VEP) investigation within 12 d from the appearance of the first signs of disease. Latency and amplitude of P100 peak were compared with normative data and between groups.RESULTS: In 58% patients, including those without signs of retrobulbar neuritis, significant slowing of conduction along the central visual pathways(P100latency lengthening) is seen. P100 amplitudes drop(signs of axonal damage) are registered less frequently(29% cases).CONCLUSION: The results indicate that visual pathways are often affected in the MS onset; mostly demyelination signs are seen. Despite MRI significance for MS diagnostic, VEPs proved to be still effective in early diagnosis of MS in children.

The Amygdala Responds Rapidly to Flashes Linked to Direct Retinal Innervation:A Flash-evoked Potential Study Across Cortical and Subcortical Visual Pathways

Rapid detection and response to visual threats are critical for survival in animals.The amygdala(AMY)is hypothesized to be involved in this process,but how it interacts with the visual system to do this remains unclear.By recording flash-evoked potentials simultaneously from the superior colliculus(SC),lateral posterior nucleus of the thalamus,AMY,lateral geniculate nucleus(LGN)and visual cortex,which belong to the cortical and subcortical pathways for visual fear processing,we investigated the temporal relationship between these regions in visual processing in rats.A quick flash-evoked potential(FEP)component was identified in the AMY.This emerged as early as in the LGN and was approximately 25 ms prior to the earliest component recorded in the SC,which was assumed to be an important area in visual fear.This quick P1 component in the AMY was not affected by restraint stress or corticosterone injection,but was diminished by RU38486,a glucocorticoid receptor blocker.By injecting a monosynaptic retrograde AAV tracer into the AMY,we found that it received a direct projection from the retina.These results confirm the existence of a direct connection from the retina to the AMY,that the latency in the AMY to flashes is equivalent to that in the sensory thalamus,and that the response is modulated by glucocorticoids.

Visual function alterations in essential tremor: A case report

Our purpose is to report alterations in contrast sensitivity function(CSF)and in the magno,parvo and koniocellular visual pathways by means of a multichannel perimeter in case of an essential tremor(ET).A complete evaluation of the visual function was performed in a 69-year old patient,including the analysis of the chromatic discrimination by the Fansworth–Munsell 100 hue test,the measurement of the CSF by the CSV-1000E test,and the detection of potential alteration patterns in the magno,parvo and koniocellular visual pathways by means of a multichannel perimeter.Visual acuity and intraocular pressure(IOP)were within the ranges of normality in both eyes.No abnormalities were detected in the fundoscopic examination and in the optical coherence tomography(OCT)exam.The results of the color vision examination were also within the ranges of normality.A signi¯cant decrease in the achromatic CSFs for right eye(RE)and left eye(LE)was detected for all spatial frequencies.The statistical global values provided by the multichannel perimeter confirms that there were significant absolute sensitivity losses compared to the normal pattern in RE.In the LE,only a statistically significant decrease in sensitivity was detected for the blue-yellow(BY)channel.The pattern standard deviation(PSD)values obtained in our patient indicated that there were significant localized losses compared to the normality pattern in the achromatic channel of the RE and in the red-green(RG)channel of the LE.Some color vision alterations may be present in ET that cannot be detected with conventional color vision tests,such as the FM 100 Hue.

Magnetic resonance diffusion tensor imaging and diffusion tensor tractography of human visual pathway

AIM: To investigate the visual pathway in normal subjects and patients with lesion involved by diffusion tensor imaging (DTI) and diffusion tensor tractography (DTT). METHODS: Thirty normal volunteers, 3 subjects with orbital tumors involved the optic nerve (ON) and 33 subjects with occipital lobe tumors involved the optic radiation (OR) (10 gliomas, 6 meningiomas and 17 cerebral metastases) undertook routine cranium magnetic resonance imaging (MRI), DTI and DTT. Visual pathway fibers were analyzed by DTI and DTT images. Test fractional anisotropy (FA) and mean diffusivity (MD) values in different part of the visual pathway. RESULTS: The whole visual pathway but optic chiasm manifested as hyperintensity in FA maps and homogenous green signal in the direction encoded color maps. The optic chiasm did not display clearly. There was no significant difference between the bilateral FA values and MD values of normal visual pathway but optic chiasm, which the FA values tested were much too low (all P>0.05). The ONs of subjects with orbital tumors were compressed and displaced. Only one subject had lower FA values and higher MD values. OR of 9 gliomas subjects were infiltrated, with displacement in 2 and disruption in 7 subjects. All OR in 6 meniongiomas subjects were displaced. OR in 17 cerebral metastases subjects all developed displacement while 7 of them had disruption also. CONCLUSION: MR-DTI is highly sensitive in manifesting visual pathway. Visual pathway can be analyzed quantitatively in FA and MD values. DTT supplies accurate three dimensional conformations of visual pathway. But optic chiasm's manifestation still needs to improve.

A visual awareness pathway in cognitive model ABGP

The cognitive model ABGP is a special model for agents,which consists of awareness,beliefs,goals and plans. The ABGP agents obtain the knowledge directly from the natural scenes only through some single preestablished rules like most agent architectures. Inspired by the biological visual cortex( V1) and the higher brain areas perceiving the visual feature,deep convolution neural networks( CNN) are introduced as a visual pathway into ABGP to build a novel visual awareness module. Then a rat-robot maze search simulation platform is constructed to validate that CNN can be used for the awareness module of ABGP. According to the simulation results,the rat-robot implemented by the ABGP with the CNN awareness module reaches the excellent performance of recognizing guideposts,which directly enhances the capability of the communication between the agent and the natural scenes and improves the ability to recognize the real world,which successfully demonstrates that an agent can independently plan its path in terms of the natural scenes.

Functional magnetic resonance imaging evaluation of visual cortex activation in patients with anterior visual pathway lesions

The aim of this study was to examine the secondary visual cortex functional disorder in patients with glaucoma and large pituitary adenoma by functional magnetic resonance imaging, and to determine the correlation between visual field defect and primary visual cortex activation. Results showed that single eye stimulation resulted in bilateral visual cortex activation in patients with glaucoma or large pituitary adenoma. Compared with the normal control group, the extent and intensity of visual cortex activation was decreased after left and right eye stimulation, and functional magnetic resonance imaging revealed a correlation between visual field defects and visual cortex activation in patients with glaucoma and large pituitary adenoma. These functional magnetic resonance imaging data suggest that anterior optic pathway lesions can cause secondary functional disorder of the visual cortex, and that visual defects are correlated with visual cortex activation.

Reduction of Interhemispheric Functional Connectivity in Sensorimotor and Visual Information Processing Pathways in Schizophrenia

Background： Previous studies have demonstrated interhemispheric functional connectivity alterations in schizophrenia. However, the relationship between these alterations and the disease state of schizophrenia is largely unknown. Therefore, we aimed to investigate this relationship using voxel-mirrored homotopic connectivity （VMHC） method. Methods： This study enrolled 36 schizophrenia patients with complete remission, 58 schizophrenia patients with incomplete remission and 55 healthy controls. The VMHC was calculated based on resting-state functional magnetic resonance imaging data. Differences in VMHC among three groups were compared using one-way analysis of variance. A brain region with a significant difference in VMHC was defined as a region of interest （ROI）, and the mean VMHC value in the ROI was extracted for the post hoc analysis, i.e., pair-wise comparisons across the three groups. Results： VMHC in the visual region （inferior occipital and fusiform gyri） and the sensorimotor region （paracentral lobule） showed significant differences among the three groups （P 〈 0.05, a false discovery rate method corrected）. Pair-wise comparisons in the post hoc analysis showed that VMHC of the visual and sensorimotor regions in schizophrenia patients with complete remission and incomplete remission was lower than that in healthy controls （P 〈 0.05, Bonferroni corrected）; however, there was no significant difference between the two patient subgroups. Conclusions： Interhemispheric functional connectivity in the sensorimotor and visual processing pathways was reduced in patients with schizophrenia, but this reduction was unrelated to the disease state; thus, this reduction may serve as a trait marker of schizophrenia.

Electrical stimulation scheme optimization for retinal prosthesis:considerations from biological perspective

Effective and safe electrical stimulation of the retinal ganglion cells is at the heart of retinal prosthesis design.However,the effectiveness and safety demand of the electrical stimulation is often at odds against each other.Besides,the nerve fiber layer above retinal ganglion cells limits the spatial resolution of stimulation.Also,current retinal prosthesis still cannot selectively activate the ON or OFF visual pathways,thus cannot relay the correct luminance information to the brain.With decades of development,the stimulation protocol for retinal implants began to tackle these problems.We believe that a novel design of electrical stimulation scheme,combined with gene therapy technique,can improve the selectivity and spatial resolution of retinal implants and further lower the damage caused by electric stimulation.

A new study on diffusion tensor imaging of the whole visual pathway fiber bundle and clinical application

Background With conventional imaging methods only the morphous of the visual nerve fiber bundles can be demonstrated, while the earlier period functional changes can not be demonstrated. We hypothesized that diffusion tensor imaging （DTI） would demonstrated the whole optic never fiber bundle and visual pathway and the earlier period functional changes. The purpose of the present study was to evaluate the application of DTI technique in the demonstration of the whole optic never fiber bundle and visual pathway, and the influence of orbital tumors on them. Methods GE 1.5T signa HD MR System, and the software package DTV2 were adopted. The total 45 subjects were enrolled, including 15 volunteers and 30 patients. All patients had ocular proptosis from minor to major. Seven patients had visual acuity decrescence. Results The nerve fiber bundles, e.g. optic chiasma, optic tract and optic radiation in posterior visual pathway were well demonstrated in all cases. Wherein, the intact whole visual pathway fiber bundles were clearly revealed in 10 volunteers and 17 patients, and optic nerve was not wholly revealed in the rest of the subjects. Shift of optic nerve caused by compression and partial deformation were seen in 7 patients with orbital tumor, in 6 of 7 patients, DTI displayed significant abscise and deformation of visual nerve. Chi-square test indicated significant correlation between visual acuity decrescence and DTI visual nerve non-display. Conclusions Visual nerve fiber bundles and the whole visual pathway were visualized in most of patients with DTI. It might be an effective method of providing imaging evidence for visual nerve fiber earlier period functional changes, and laid a foundation for the study in other cranial nerves. Chin Med J 2009; 122（2）： 178-182

Ability of Mn2＋ to Permeate the Eye and Availability of Manganese-enhanced Magnetic Resonance Imaging for Visual Pathway Imaging via Topical Administration

Background： Manganese-enhanced magnetic resonance imaging （MEMR1） for visual pathway imaging via topical administration requires further research. This study investigated the permeability of the corneal epithelium and corneal toxicity after topical administration of Mn2＋ to understand the applicability of MEMR1. Methods： Forty New Zealand rabbits were divided into 0.05 mool/L, 0.10 mol/L, and 0.20 mol/L groups as well as a control group （n ： 10 in each group）. Each group was i-hrther subdivided into epithelium-removed and epithelium-intact subgroups （n = 5 in each subgroup）. Rabbits were given 8 drops of MnCl2 in 5 min intervals. The Mn2＋ concentrations in the aqueous and vitreous humors were analyzed using inductively coupled plasma-mass spectrometry at different time points. MEMRI scanning was carried out to image the visual pathway after 24 h. The corneal toxicity of Mn2＋ was evaluated with corneal imaging and pathology slices. Results： Between the aqueous and vitreous humors, there was a 10 h lag for the peak Mn2＋ concentration times. The intraocular Mn2＋ concentration increased with the concentration gradients ofMn2＋ and was higher in the epithelium-removed subgroup than that in the epithelium-intact subgroup. The enhancement of the visual pathway was achieved ill the 0.10 mol/L and 0.20 mol/L epithelium-removed subgroups. The corresponding peak concentrations of Mn2. were 5087 ~ 666 ng/ml, 22920 ± 1188 ng/ml ill the aqueous humor and 884 ± 78 ng/ml, 2556 ± 492 ng/ml in the vitreous body, respectively. Corneal injury was evident in the epithelium-removed and 0.20 mol/L epithelium-intact subgroups. Conclusions： The corneal epithelium is a barrier to Mn2＋, and the iris and lens septum might be another intraocular banier to the permeation of Mn2＋. An elevated Mn2＋ concentration contributes to the increased permeation of Mn2＋, higher MEMRI signal, and corneal toxicity. The enhancement of the visual pathway requires an effective Mn2＋ concentration in the vitreous body.

FunHoP:Enhanced Visualization and Analysis of Functionally Homologous Proteins in Complex Metabolic Networks

Cytoscape is often used for visualization and analysis of metabolic pathways.For example,based on KEGG data,a reader for KEGG Markup Language(KGML)is used to load files into Cytoscape.However,although multiple genes can be responsible for the same reaction,the KGMLreader KEGGScape only presents the first listed gene in a network node for a given reaction.This can lead to incorrect interpretations of the pathways.Our new method,FunHoP,shows all possible genes in each node,making the pathways more complete.FunHoP collapses all genes in a node into one measurement using read counts from RNA-seq.Assuming that activity for an enzymatic reaction mainly depends upon the gene with the highest number of reads,and weighting the reads on gene length and ratio,a new expression value is calculated for the node as a whole.Differential expression at node level is then applied to the networks.Using prostate cancer as model,we integrate RNA-seq data from two patient cohorts with metabolism data from literature.Here we show that FunHoP gives more consistent pathways that are easier to interpret biologically.Code and documentation for running FunHoP can be found at https://github.com/kjerstirise/FunHoP.

Inflammation in the anterior visual pathway in multiple sclerosis:what do the animal models teach us?

A provocative and overly reductive mantra is that"the back of the eye is the front of the brain".Retinal imaging techniques that take advantage of this"window"to the central nervous system can provide valuable information regarding injury to the nervous system with relative ease and with a limited burden to patients.The retina develops embryonically as part of the neuroectoderm,is made up principally of neurons and their supporting cells,and is synaptically tied to the central nervous system(CNS).This has led to significant interest in using retinal health as a biomarker for brain health-given the relatively limited accessibility of brain tissue in chronic neurodegenerative diseases that progress over decades.The retina is not truly part of the CNS,and as with much of brain imaging-the grounds for asserting the pathological specificity of retinal imaging is limited.Biophotonics-based methods such as optical coherence tomography indirectly provide an opportunity to evaluate retinal neurodegeneration,while autopsy studies,histology and immunohistochemistry predominate as the methods that collect direct pathological data.Our understanding of pathological retinal lesions characteristic of demyelinating diseases,specifically diseases showing anterior visual pathway involvement,has grown significantly in recent years.However,much of the underlying pathobiology of injury remain unexplored.This review aims to highlight the major pathological features of the retina in multiple sclerosis,and its most used animal models(experimental autoimmune encephalomyelitis and cuprizone),with a particular focus on n the role of inflammation.

Maritime Target Saliency Detection for UAV Based on the Stimulation Competition Selection Mechanism of Raptor Vision

A maritime target saliency detection method inspired by the stimulation competition and selection mechanism of raptor vision is presented for the airborne vision system of unmanned aerial vehicle(UAV)in an unknown maritime environment.The stimulation competition and selection mechanism in the visual pathway of raptor vision based on the phenomenon of raptor capturing prey in complex scenes are studied.Then,the mathematical model of the stimulation competition and selection mechanism of raptor vision is established and employed for the salient object detection.Popular image datasets and practical scene datasets are applied to verify the effectiveness of the presented method.Results show that the detection performance of the proposed method is better than that of other comparison methods.The proposed algorithm provides an idea for maritime target salient detection and cross-domain joint mission for UAV or other unmanned equipment.

针刺治疗屈光参差性弱视:一项随机对照试验及其潜在起效机制

Objective:To evaluate the effect of acupuncture on anisometropic amblyopia(AA)and explore its potential mechanism for children with AA.Methods:Seventy-six children with monocular AA were randomized into a conventional treatment group and a combined treatment group of acupuncture and conventional treatment,with 38 patients in each group.In the conventional treatment group,on the base of patching regimen,the red flashing,grating and visual stimulation were delivered.Each approach lasted for 5 min per session and was given once every two days,three times a week,for 4 consecutive weeks.In the acupuncture-combined treatment group,on the base of the regimen of conventional treatment group,acupuncture was applied to Jingming(BL1),Cuanzhu(BL2),Fengchi(GB20)and Guangming(GB37),with needles retained for 20 min per session,once every two days,three times of intervention a week and for 4 consecutive weeks.Before and after treatment,the best corrected vision acuity(BCVA)was observed to evaluate the clinical effect in the two groups.Before treatment started,15 patients with AA on left side were randomized selected from each group and the resting-state functional magnetic resonance imaging(rs-fMRI)was operated before and after treatment.Simultaneously,eight healthy children with normal visual acuity were recruited to be the normal control group and received one-time rs-fMRI scanning.Based on the activation likelihood estimation(ALE),the visual"what"pathway network was constructed.By analyzing the amplitude of low frequency fluctuation(ALFF)and the regional homogeneity(ReHo),the differences in the regional autonomous function activities in the key brain areas of the"what"pathway were compared among the three groups.Results:(1)Clinical effect:After treatment,BCVA was(0.6[0.5,0.6]),higher than that(0.4[0.3,0.5])before treatment,presenting the statistical difference(P<0.05)in the conventional treatment group.BCVA was(0.6[0.6,0.8]),higher than that(0.4[0.4,0.5])before treatment,presenting the statistical difference(P<0.05)in the acupuncture-combined treatment group.BCVA in the acupuncture-combined treatment group was higher than that of the conventional treatment group(P<0.05)after treatment.The total effective rate was 86.1%in the acupuncture-combined treatment group,higher than that(65.8%)of the conventional treatment group(P<0.05).(2)Mechanism:(1)ALFF:In comparison with the healthy control group,the ALFF in the primary visual cortex of the"what"pathway for AA children was reduced significantly(P<0.05),and ALFF in the right fusiform gyrus and the right inferior temporal gyrus increased significantly when compared with the healthy children(P<0.05).Compared with that before treatment,there was no significant difference in the brain areas of the"what"pathway after treatment in the conventional treatment group(P>0.05).In the acupuncture-combined treatment group,ALFF in the right inferior occipital gyrus and the right fusiform gyrus of the"what"pathway increased after treatment when compared with that before treatment(P<0.05).After treatment,in comparison with the conventional treatment group,there was no significant difference in the brain areas of"what"pathway in the acupuncture-combined treatment group(P>0.05).(2)ReHo:ReHo in the right inferior occipital gyrus,the right fusiform gyrus and the right inferior temporal gyrus in the"what"pathway was elevated significantly in AA children when compared with that in the healthy control group(P<0.05).ReHo of the left inferior occipital gyrus and the left fusiform gyrus increased significantly after treatment when compared with that before treatment in the conventional treatment group(P<0.05).ReHo of the right inferior occipital gyrus,the left and the right fusiform gyrus increased significantly after treatment when compared with that before treatment in the acupuncture-combined treatment group(P<0.05).After treatment,ReHo of the right inferior temporal gyrus in the"what"pathway in the acupuncture-combined treatment group was significantly higher than that of the conventional treatment group(P<0.05).Conclusion:The acupuncture combined with conventional treatment improves BCVA and the total effective rate of AA children.The changes in the regional function activity of the brain areas within the"what"pathway were dominated by the compensatory increase of the autonomous activity in the occipital lobe(inferior occipital gyrus)and the temporal lobe(inferior temporal gyrus)in AA children.Both conventional treatment and acupuncture can enhance the intensity of autonomous function activities in the occipital lobe(inferior occipital gyrus)and the temporal lobe(fusiform gyrus/inferior temporal gyrus)in the"what"pathway so as to relieve visual impairment.ReHo in the inferior temporal gyrus in the acupuncture-combined treatment group was higher than that of the conventional treatment group and it suggests that the inferior temporal gyrus may be the key brain area to the improvement of visual function in the"what"pathway.