Optomotor System Research Articles

NLRP3 Inflammasome Priming in the Retina of Diabetic Mice Requires REDD1-Dependent Activation of GSK3β.

Inflammasome activation has been implicated in the development of retinal complications caused by diabetes. This study was designed to identify signaling events that promote retinal NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome activation in response to diabetes. Diabetes was induced in mice by streptozotocin administration. Retinas were examined after 16 weeks of diabetes. Human MIO-M1 Müller cells were exposed to hyperglycemic culture conditions. Genetic and pharmacological interventions were used to interrogate signaling pathways. Visual function was assessed in mice using a virtual optomotor system. In the retina of diabetic mice and in Müller cell cultures, NLRP3 and interleukin-1β (IL-1β) were increased in response to hyperglycemic conditions and the stress response protein Regulated in Development and DNA damage 1 (REDD1) was required for the effect. REDD1 deletion prevented caspase-1 activation in Müller cells exposed to hyperglycemic conditions and reduced IL-1β release. REDD1 promoted nuclear factor κB signaling in cells exposed to hyperglycemic conditions, which was necessary for an increase in NLRP3. Expression of a constitutively active GSK3β variant restored NLRP3 expression in REDD1-deficient cells exposed to hyperglycemic conditions. GSK3 activity was necessary for increased NLRP3 expression in the retina of diabetic mice and in cells exposed to hyperglycemic conditions. Müller glia-specific REDD1 deletion prevented increased retinal NLRP3 levels and deficits in contrast sensitivity in diabetic mice. The data support a role for REDD1-dependent activation of GSK3β in NLRP3 inflammasome transcriptional priming and in the production of IL-1β by Müller glia in response to diabetes.

A Robust Optomotor Assay for Assessing the Efficacy of Optogenetic Tools for Vision Restoration.

PurposeTo develop an animal behavioral assay for the quantitative assessment of the functional efficacy of optogenetic therapies.MethodsA triple-knockout (TKO) mouse line, Gnat1−/−Cnga3−/−Opn4−/−, and a double-knockout mouse line, Gnat1−/−Cnga3−/−, were employed. The expression of channelrhodopsin-2 (ChR2) and its three more light-sensitive mutants, ChR2-L132C, ChR2-L132C/T159C, and ChR2-132C/T159S, in inner retinal neurons was achieved using rAAV2 vectors via intravitreal delivery. Pupillary constriction was assessed by measuring the pupil diameter. The optomotor response (OMR) was examined using a homemade optomotor system equipped with light-emitting diodes as light stimulation.ResultsA robust OMR was restored in the ChR2-mutant-expressing TKO mice; however, significant pupillary constriction was observed only for the ChR2-L132C/T159S mutant. The ability to evoke an OMR was dependent on both the light intensity and grating frequency. The most light-sensitive frequency for the three ChR2 mutants was approximately 0.042 cycles per degree. Among the three ChR2 mutants, ChR2-L132C/T159S was the most light sensitive, followed by ChR2-L132C/T159C and ChR2-L132C. Melanopsin-mediated pupillary constriction resulted in a substantial reduction in the light sensitivity of the ChR2-mediated OMR.ConclusionsThe OMR assay using TKO mice enabled the quantitative assessment of the efficacy of different optogenetic tools and the properties of optogenetically restored vision. Thus, the assay can serve as a valuable tool for developing effective optogenetic therapies.

The eye as a window to the brain: an innovative mouse model for retinal alpha-synucleinopathy

Event Abstract Back to Event The eye as a window to the brain: an innovative mouse model for retinal alpha-synucleinopathy Lien Veys1*, Lien Andries1, Evy Lefevere1, Chris Van Den Haute2, Veerle Baekelandt2, Lieve Moons1 and Lies De Groef1 1 KU Leuven, Biology, Belgium 2 KU Leuven, Neurosciences, Belgium Although it is well-documented that many patients with Parkinson’s disease (PD) present with visual disabilities, scientific research has largely neglected the impact of PD on the retina. Nevertheless, a profound understanding of the retinal manifestations of PD would not only help to gain new insights into the pathogenesis of PD, it would also open up new avenues to improved disease management. In this study, we exploit the advantages of the retina - being the most accessible part of the central nervous system- as a model organ for CNS research. The aim of this study is to develop and characterize a novel mouse model for the study of PD in the retina, based on local, viral vector-mediated overexpression of α-synuclein (αSYN). In a pilot study, C57BL/6N mice were intravitreally injected in the right eye with an adeno-associated viral vector in order to overexpress αSYN in the retina. Efficient and homogenous transduction of the entire retina was achieved and resulted in αSYN overexpression in neurons in the ganglion cell layer and inner nuclear layer as soon as 2 weeks post injection. We observed retinal thinning starting from week 14 with optical coherence tomography (OCT). Confocal scanning laser ophthalmoscopy (cSLO) also revealed autofluorescent spots at that same time point, indicative of protein aggregation. Together, this indicates αSYN aggregation and neurodegeneration. The latter was also demonstrated when we tested visual function with a virtual optomotor system at that time point: reduced visual acuity was shown. Together, these results suggest that the retina can be used as a model organ to study the effect of (or the link between) α-synucleinopathy on neuronal survival. We are currently confirming this pilot data, and further characterizing this novel model using electrophysiology, cSLO and ‘detection of apoptosing retinal cells’ techniques. In further studies, we intend to validate this disease model as a screening tool to evaluate the impact of therapeutic interventions on PD disease progression. Keywords: alpha-Synuclein, Parkinson’s disease, in vivo follow-up, Retina, mouse model Conference: 12th National Congress of the Belgian Society for Neuroscience, Gent, Belgium, 22 May - 22 May, 2017. Presentation Type: Poster Presentation Topic: Disorders of the Nervous System Citation: Veys L, Andries L, Lefevere E, Van Den Haute C, Baekelandt V, Moons L and De Groef L (2019). The eye as a window to the brain: an innovative mouse model for retinal alpha-synucleinopathy. Front. Neurosci. Conference Abstract: 12th National Congress of the Belgian Society for Neuroscience. doi: 10.3389/conf.fnins.2017.94.00106 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 18 Apr 2017; Published Online: 25 Jan 2019. * Correspondence: Miss. Lien Veys, KU Leuven, Biology, Leuven, Vlaams-Brabant, 3000, Belgium, lien.veys@kuleuven.be Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Lien Veys Lien Andries Evy Lefevere Chris Van Den Haute Veerle Baekelandt Lieve Moons Lies De Groef Google Lien Veys Lien Andries Evy Lefevere Chris Van Den Haute Veerle Baekelandt Lieve Moons Lies De Groef Google Scholar Lien Veys Lien Andries Evy Lefevere Chris Van Den Haute Veerle Baekelandt Lieve Moons Lies De Groef PubMed Lien Veys Lien Andries Evy Lefevere Chris Van Den Haute Veerle Baekelandt Lieve Moons Lies De Groef Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

A neural model of the optomotor system accounts for ordered responses to decreasing stimulus spatial frequencies

In insects the optomotor response produces a motor action to compensate for unintended body rotation. The response is generally modeled as a Reichardt-Hassenstein (HSD) or Barlow-Levick (BL) correlation detector, as anatomical and physiological studies in Drosophila melanogaster have demonstrated consistent neural pathways and responses in the insect brain [1]. Recordings from the descending neurons carrying the optomotor response signal in honeybees indicate an ordering effect for different stimulus spatial frequencies, with a greater response with decreasing frequency [2] (see Figure ​Figure1A),1A), which is not accounted for by HSD or BL correlation detectors. Figure 1 A. Cartoon of ordering effect indicated by honeybee descending neuron responses. Spatial frequency decreases from blue to green. B. Model diagram showing annealed synapses (coloured, same colours indicate same synaptic conductance). C. Slice of annealing ... We present a model in the SpineML format of the optomotor system, using Izhikevich point neurons tuned to match the respective physiological responses, which is shown in Figure ​Figure1B.1B. To examine if the model reproduces the ordering effect found in the honeybee we performed simulated annealing on four conductance values in the model, as shown in Figure ​Figure1.1. The objective function is designed to maximize: correct ordering; a 10Hz maximum response; and contrast between responses to forward and reverse motion. A. The data was imported into a commercial software package (MATLAB 7.14, The MathWorks Inc., Natick, MA, 2012) for analysis and interpolated onto a 414 grid. A 3D slice of this 4D grid can be seen in Figure ​Figure1C.1C. Spatial frequencies of 32.7, 18.9 and 9.5 Hz are used. A stable region in which a high value of the objective function, and thus correct spatial frequency ordering, could be obtained was found. In the stable region the onset pathway activity is low, leading to offset activity dominating. A RHD using the model up to the Medulla does not show correct ordering.

The eye screen design in Czech Centre for Phenogenomics and selected models for eye diseases

SummaryThe eye screen will be part of emerging Czech Centre for Phenogenomics (CCP) in proximity to Prague. The purpose of our eye screen will be the detection of various eye abnormalities in eye morphology and eye physiology. We would like to examine retina structure abnormalities using optical coherence tomography, or anterior segment abnormalities using Scheimpflug imaging. In addition, we plan to perform functional analysis of the visual system using virtual optomotor system. Finally, retinal function will be tested by electroretinography.Based on our previous work, we have expertise especially in the field of transcriptional regulation of eye development. Specifically, our interest is transcriptional regulation of Pax6 that is crucial for eye development in various species. Pax6 haploinsufficiency is characterized by aniridia in human and by small eye phenotype in mouse. Therefore, here we describe our results using transgenic mouse models to reveal requirement of upstream regulators of Pax6 for lens induction.

Vision-based flight control in the hawkmoth Hyles lineata.

Vision is a key sensory modality for flying insects, playing an important role in guidance, navigation and control. Here, we use a virtual-reality flight simulator to measure the optomotor responses of the hawkmoth Hyles lineata, and use a published linear-time invariant model of the flight dynamics to interpret the function of the measured responses in flight stabilization and control. We recorded the forces and moments produced during oscillation of the visual field in roll, pitch and yaw, varying the temporal frequency, amplitude or spatial frequency of the stimulus. The moths' responses were strongly dependent upon contrast frequency, as expected if the optomotor system uses correlation-type motion detectors to sense self-motion. The flight dynamics model predicts that roll angle feedback is needed to stabilize the lateral dynamics, and that a combination of pitch angle and pitch rate feedback is most effective in stabilizing the longitudinal dynamics. The moths' responses to roll and pitch stimuli coincided qualitatively with these functional predictions. The moths produced coupled roll and yaw moments in response to yaw stimuli, which could help to reduce the energetic cost of correcting heading. Our results emphasize the close relationship between physics and physiology in the stabilization of insect flight.

Ablation of Retinal Horizontal Cells from Adult Mice Leads to Rod Degeneration and Remodeling in the Outer Retina

In the brain, including the retina, interneurons show an enormous structural and functional diversity. Retinal horizontal cells represent a class of interneurons that form triad synapses with photoreceptors and ON bipolar cells. At this first retinal synapse, horizontal cells modulate signal transmission from photoreceptors to bipolar cells by feedback and feedforward inhibition. To test how the fully developed retina reacts to the specific loss of horizontal cells, these interneurons were specifically ablated from adult mice using the diphtheria toxin (DT)/DT-receptor system and the connexin57 promoter. Following ablation, the retinal network responded with extensive remodeling: rods retracted their axons from the outer plexiform layer and partially degenerated, whereas cones survived. Cone pedicles remained in the outer plexiform layer and preserved synaptic contacts with OFF but not with ON bipolar cells. Consistently, the retinal ON pathway was impaired, leading to reduced amplitudes and prolonged latencies in electroretinograms. However, ganglion cell responses showed only slight changes in time course, presumably because ON bipolar cells formed multiple ectopic synapses with photoreceptors, and visual performance, assessed with an optomotor system, was only mildly affected. Thus, the loss of an entire interneuron class can be largely compensated even by the adult retinal network.

Visual capabilities and cortical maps in BALB/c mice

By combining behavioural analyses with intrinsic signal optical imaging, we analysed visual performance and visual cortical activity in the albino mouse strain BALB/c, which is increasingly being used as an animal model of neuropsychological disorders. Visual acuity, as measured by a virtual-reality optomotor system, was 0.12 cycles per degree (cyc/deg) in BALB/c mice and 0.39 cyc/deg in pigmented C57BL/6 mice. Surprisingly, BALB/c mice showed reflexive head movements against the direction of the rotating stimulus. Contrast sensitivity was significantly lower in BALB/c mice (45% contrast at 0.064 cyc/deg) than in C57BL/6 mice (6% contrast). In the visual water task, visual acuity was 0.3 cyc/deg in BALB/c mice and 0.59 cyc/deg in C57BL/6 mice. Thus, the visual performance of BALB/c mice was significantly impaired in both behavioural tests - visual acuity was ∼ 0.3 cyc/deg lower than in C57BL/6 mice, and contrast sensitivity was reduced by a factor of ∼ 8. In BALB/c mice, visual cortical maps induced by stimulation of the contralateral eye were normal in both activation strength and retinotopic map quality. In contrast, maps induced by ipsilateral eye stimulation differed significantly between the strains - activity in a region representing 15° to 19° elevation in the visual field was significantly weaker in BALB/c mice than in C57BL/6 mice. Taken together, our observations show that BALB/c mice, like the albino animals of other species, have a significantly lower visual performance than C57BL/6 mice and a modified cortical representation of the ipsilateral eye that may impair stereopsis. Thus, our results caution against disregarding vision as a confounding factor in behavioural tests of neuropsychological disorders.

Simvastatin Improves Retinal Ganglion Cell Survival and Spatial Vision after Acute Retinal Ischemia/Reperfusion in Mice

The major aims of this study were to evaluate the effect of retinal ischemia by behavioral testing and histologic analyses, to visualize ischemia-induced changes of cortical activity by optical imaging of intrinsic signals, and to test the therapeutic effectiveness of simvastatin. Retinal ischemia was induced monocularly by elevating intraocular pressure. Visual function was tested behaviorally with a virtual reality optomotor system, physiologically with optical imaging of intrinsic signals, and histologically by counting the surviving retinal ganglion cells (RGCs) in the same animal. Visual acuity (-38%) and contrast sensitivity (-78%) were significantly reduced 6 days after ischemia compared with controls. The number of RGCs was reduced by 16%. In contrast, optical imaging revealed essentially unchanged cortical activity maps in spite of the lesion. Treatment of mice with simvastatin applied after the ischemic insult significantly improved both visual function as measured behaviorally (~95% visual acuity, ~165% contrast sensitivity) and RGC survival (~30%) compared with vehicle-treated animals (~42% visual acuity, ~85% contrast sensitivity). This specific combination of behavioral measurements of visual function, cortical activity imaging, and histologic analyses is ideally suited to follow ischemia-induced changes and to monitor the effect of therapeutic approaches. Statin therapy may be a promising pharmacologic tool for the treatment of acute retinal ischemia in particular because, in our study, simvastatin was applied after ischemia, a treatment regimen with much greater clinical relevance than preventive administration, as in previous studies.

Non-Linear Neuronal Responses as an Emergent Property of Afferent Networks: A Case Study of the Locust Lobula Giant Movement Detector

In principle it appears advantageous for single neurons to perform non-linear operations. Indeed it has been reported that some neurons show signatures of such operations in their electrophysiological response. A particular case in point is the Lobula Giant Movement Detector (LGMD) neuron of the locust, which is reported to locally perform a functional multiplication. Given the wide ramifications of this suggestion with respect to our understanding of neuronal computations, it is essential that this interpretation of the LGMD as a local multiplication unit is thoroughly tested. Here we evaluate an alternative model that tests the hypothesis that the non-linear responses of the LGMD neuron emerge from the interactions of many neurons in the opto-motor processing structure of the locust. We show, by exposing our model to standard LGMD stimulation protocols, that the properties of the LGMD that were seen as a hallmark of local non-linear operations can be explained as emerging from the dynamics of the pre-synaptic network. Moreover, we demonstrate that these properties strongly depend on the details of the synaptic projections from the medulla to the LGMD. From these observations we deduce a number of testable predictions. To assess the real-time properties of our model we applied it to a high-speed robot. These robot results show that our model of the locust opto-motor system is able to reliably stabilize the movement trajectory of the robot and can robustly support collision avoidance. In addition, these behavioural experiments suggest that the emergent non-linear responses of the LGMD neuron enhance the system's collision detection acuity. We show how all reported properties of this neuron are consistently reproduced by this alternative model, and how they emerge from the overall opto-motor processing structure of the locust. Hence, our results propose an alternative view on neuronal computation that emphasizes the network properties as opposed to the local transformations that can be performed by single neurons.

Reduced Corneal Thickness and Enlarged Anterior Chamber in a Novel ColVIIIa2G257DMutant Mouse

The purpose of this study was the morphologic and genetic characterization of the novel eye size mutant Aca23 in the mouse. The eyes of the mutants were characterized in vivo by optical low-coherence interferometry, Scheimpflug imaging, and funduscopy. Visual acuity was examined using a virtual optomotor system. Morphology was studied by histology, in situ hybridization, and immunohistochemistry. Linkage analysis was performed using genomewide scans with single nucleotide polymorphisms and microsatellite markers. Aca23 is a new semidominant eye size mutant that was discovered in an ENU mutagenesis screen. The phenotype includes increased anterior chamber depths, extended axial lengths, and reduced thickness of corneal layers. Aca23 was mapped to chromosome 4. A G-->A point mutation was identified at cDNA position 770 of Col8a2 encoding collagen VIII alpha2. The transition results in a G257D amino acid exchange affecting a highly conserved glycine residue in the collagenous domain. Proliferation of corneal endothelium, eye fundus, and visual acuity are not affected. The mouse mutant Aca23 described here offers the first point mutation of the Col8a2 gene in the mouse. The results of this study suggest that a functional collagen VIII alpha2 is essential for the correct assembly of the Descemet's membrane and for corneal stability. Aca23 might be used as a novel model for keratoglobus.

Age-Dependent Ocular Dominance Plasticity in Adult Mice

BackgroundShort monocular deprivation (4 days) induces a shift in the ocular dominance of binocular neurons in the juvenile mouse visual cortex but is ineffective in adults. Recently, it has been shown that an ocular dominance shift can still be elicited in young adults (around 90 days of age) by longer periods of deprivation (7 days). Whether the same is true also for fully mature animals is not yet known.Methodology/Principal FindingsWe therefore studied the effects of different periods of monocular deprivation (4, 7, 14 days) on ocular dominance in C57Bl/6 mice of different ages (25 days, 90–100 days, 109–158 days, 208–230 days) using optical imaging of intrinsic signals. In addition, we used a virtual optomotor system to monitor visual acuity of the open eye in the same animals during deprivation. We observed that ocular dominance plasticity after 7 days of monocular deprivation was pronounced in young adult mice (90–100 days) but significantly weaker already in the next age group (109–158 days). In animals older than 208 days, ocular dominance plasticity was absent even after 14 days of monocular deprivation. Visual acuity of the open eye increased in all age groups, but this interocular plasticity also declined with age, although to a much lesser degree than the optically detected ocular dominance shift.Conclusions/SignificanceThese data indicate that there is an age-dependence of both ocular dominance plasticity and the enhancement of vision after monocular deprivation in mice: ocular dominance plasticity in binocular visual cortex is most pronounced in young animals, reduced but present in adolescence and absent in fully mature animals older than 110 days of age. Mice are thus not basically different in ocular dominance plasticity from cats and monkeys which is an absolutely essential prerequisite for their use as valid model systems of human visual disorders.

Varying the sign and gain of optomotor feedback provides insights into mechanisms of course control in walking land crabs, Cardisoma guanhumi

This study used a walking compensator consisting of a hollow styrofoam ball supported on a cushion of air. The crab, held above the ball, is unable to rotate or translate, but instead moves the ball under its feet. Visual stimuli, mimicking rotational optic flow, are generated by computers and projected onto two screens that cover 240° of the crab's visual field. Optical computer mice monitor movements of the ball about all three axes, and the signals from ball rotation about a vertical axis are fed back to the computers generating visual stimuli. In this way, the visual consequences of turns can be fed back to the visual system, with experimenter control of gain and sign. Eye movements are recorded using a capacitative position-sensing device. This apparatus was used to analyse the control systems that govern both optomotor body turns, used in course control, and compensatory eye movements. Results demonstrate that the optomotor system has a high gain and long time constant. Thus, responses to sinusoidal visual inputs with positive rather than negative feedback do not, as might be expected, simply generate body turns in the opposite direction to the visual input. Instead, they are dominated by the direction of turning that the crab initially makes, so that the turning movement is unidirectional and no longer follows the sinusoidal component of the visual input. Modelling such responses using Simulink (a Matlab package) allows us to test different models of the control system

Sexual Dimorphism in the Hoverfly Motion Vision Pathway

Many insects perform high-speed aerial maneuvers in which they navigate through visually complex surrounds. Among insects, hoverflies stand out, with males switching from stationary hovering to high-speed pursuit at extreme angular velocities [1]. In dipterans, 50-60 large interneurons -- the lobula-plate tangential cells (LPTCs) -- detect changes in optic flow experienced during flight [2-5]. It has been predicted that large LPTC receptive fields are a requirement of accurate "matched filters" of optic flow [6]. Whereas many fly taxa have three horizontal system (HS) LPTC neurons in each hemisphere, hoverflies have four [7], possibly reflecting the more sophisticated flight behavior. We here show that the most dorsal hoverfly neuron (HS north [HSN]) is sexually dimorphic, with the male receptive field substantially smaller than in females or in either sex of blowflies. The (hoverfly-specific) HSN equatorial (HSNE) is, however, sexually isomorphic. Using complex optic flow, we show that HSN, despite its smaller receptive field, codes yaw velocity as well as HSNE. Responses to a target moving against a plain or textured background suggest that the male HSN could potentially play a role in target pursuit under some conditions.

Response Properties of Motion-Sensitive Visual Interneurons in the Lobula Plate of Drosophila melanogaster

The crystalline-like structure of the optic lobes of the fruit fly Drosophila melanogaster has made them a model system for the study of neuronal cell-fate determination, axonal path finding, and target selection. For functional studies, however, the small size of the constituting visual interneurons has so far presented a formidable barrier. We have overcome this problem by establishing in vivo whole-cell recordings from genetically targeted visual interneurons of Drosophila. Here, we describe the response properties of six motion-sensitive large-field neurons in the lobula plate that form a network consisting of individually identifiable, directionally selective cells most sensitive to vertical image motion (VS cells). Individual VS cell responses to visual motion stimuli exhibit all the characteristics that are indicative of presynaptic input from elementary motion detectors of the correlation type. Different VS cells possess distinct receptive fields that are arranged sequentially along the eye's azimuth, corresponding to their characteristic cellular morphology and position within the retinotopically organized lobula plate. In addition, lateral connections between individual VS cells cause strongly overlapping receptive fields that are wider than expected from their dendritic input. Our results suggest that motion vision in different dipteran fly species is accomplished in similar circuitries and according to common algorithmic rules. The underlying neural mechanisms of population coding within the VS cell network and of elementary motion detection, respectively, can now be analyzed by the combination of electrophysiology and genetic intervention in Drosophila.

Diminished plasticity of visual function and sensory maps after cortical stroke in mice

Event Abstract Back to Event Diminished plasticity of visual function and sensory maps after cortical stroke in mice Franziska Greifzu1*, Silvio Schmidt2, Friedrich Schmidt1, Otto W. Witte2 and Siegrid Löwel1 1 Friedrich-Schiller-University, Germany 2 University of Jena Medical School, Germany Stroke is a major cause of death and disability in the industrialized countries. It is an encouraging observation that clinically most patients who do suffer from stroke recover to some degree from the deficits which they incur. The most straightforward assumption is usually that this is due to plasticity. Many in vitro studies indicated that there is an increased plasticity in the perilesional zone of cortical infarcts. In the present study we investigated in vivo the impact of a photothrombotically induced cortical stroke on the plasticity of the neighbouring visual cortex after short periods of monocular deprivation (MD). Visual function was analyzed behaviourally with a virtual optomotor system. In addition, visual cortical maps were recorded using intrinsic signal optical imaging. After 7 days of MD, control animals showed a significant enhancement of visual acuity in the non-deprived eye and a significant ocular dominance shift towards the open eye in the optical imaging experiments. In contrast, in animals with a cortical stroke, both the enhancement of visual acuity and the ocular dominance shift were significantly lower. Thus our in vivo data rather indicate that neuronal plasticity is diminished in the surround of a cortical infarct. Conference: Bernstein Symposium 2008, Munich, Germany, 8 Oct - 10 Oct, 2008. Presentation Type: Poster Presentation Topic: All Abstracts Citation: Greifzu F, Schmidt S, Schmidt F, Witte OW and Löwel S (2008). Diminished plasticity of visual function and sensory maps after cortical stroke in mice. Front. Comput. Neurosci. Conference Abstract: Bernstein Symposium 2008. doi: 10.3389/conf.neuro.10.2008.01.052 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 14 Nov 2008; Published Online: 14 Nov 2008. * Correspondence: Franziska Greifzu, Friedrich-Schiller-University, Jena, Germany, Franziska.Greifzu@uni-jena.de Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Franziska Greifzu Silvio Schmidt Friedrich Schmidt Otto W Witte Siegrid Löwel Google Franziska Greifzu Silvio Schmidt Friedrich Schmidt Otto W Witte Siegrid Löwel Google Scholar Franziska Greifzu Silvio Schmidt Friedrich Schmidt Otto W Witte Siegrid Löwel PubMed Franziska Greifzu Silvio Schmidt Friedrich Schmidt Otto W Witte Siegrid Löwel Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

A fly-locust based neuronal control system applied to an unmanned aerial vehicle: the invertebrate neuronal principles for course stabilization, altitude control and collision avoidance

The most versatile and robust flying machines are still those produced by nature through evolution. The solutions to the 6 DOF control problem faced by these machines are implemented in extremely small neuronal structures comprising thousands of neurons. Hence, the biological principles of flight control are not only very effective but also efficient in terms of their implementation. An important question is to what extent these principles can be generalized to man-made flying platforms. Here, this question is investigated in relation to the computational and behavioral principles of the opto-motor system of the fly and locust. The aim is to provide a control infrastructure based only on biologically plausible and realistic neuronal models of the insect opto-motor system. It is shown that relying solely on vision, biologically constrained neuronal models of the fly visual system suffice for course stabilization and altitude control of a blimp-based UAV. Moreover, the system is augmented with a collision avoidance model based on the Lobula Giant Movement Detector neuron of the Locust. It is shown that the biologically constrained course stabilization model is highly robust and that the combined model is able to perform autonomous indoor flight.

Insect Navigation: Measuring Travel Distance across Ground and through Air

Walking insects probably monitor leg movements to estimate how far they travel, whereas flying insects monitor optic flow.

Rapid Quantification of Adult and Developing Mouse Spatial Vision Using a Virtual Optomotor System

To develop a simple, rapid method of quantifying the spatial vision of mice. A rotating cylinder covered with a vertical sine wave grating was calculated and drawn in virtual three-dimensional (3-D) space on four computer monitors facing to form a square. C57BL/6 mice standing unrestrained on a platform in the center of the square tracked the grating with reflexive head and neck movements. The spatial frequency of the grating was clamped at the viewing position by repeatedly recentering the cylinder on the head. Acuity was quantified by increasing the spatial frequency of the grating until an optomotor response could not be elicited. Contrast sensitivity was measured at spatial frequencies between 0.03 and 0.35 cyc/deg. Grating acuity was measurable on the day of eye opening (postnatal day [P]15: mean acuity, 0.031 cyc/deg) and reached a maximum (approximately 0.4 cyc/deg) by P24. A peak in the contrast sensitivity function emerged on P16 (4.7, or 21% contrast at 0.064 cyc/deg). The peak remained at 0.064 cyc/deg and climbed to a maximum sensitivity of 24.5, or 4% contrast, by P29. Acuity was obtained in each mouse in <10 minutes, and a detailed contrast sensitivity curve was generated in approximately 30 minutes. The virtual optomotor system provides a simple and precise method for rapidly quantifying mouse vision. Behavioral measures of vision in mice are essential for interpreting the results of experiments designed to reveal the cellular and molecular mechanisms of vision and visual development and for evaluating potential treatments for visual diseases.

Neural Processing of Naturalistic Optic Flow

Stimuli traditionally used for analyzing visual information processing are much simpler than what an animal sees in normal life. When characterized with traditional stimuli, neuronal responses were found to depend on various parameters such as contrast, texture, or velocity of motion, and thus were highly ambiguous. In behavioral situations, all of these parameters change simultaneously and differently in different parts of the visual field. Thus it is hardly possible to predict from traditional analyses what information is encoded by neurons in behavioral situations. Therefore, we characterized an identified neuron in the optomotor system of the blowfly with image sequences as they were seen by animals walking in a structured environment. We conclude that during walking, the response of the neuron reflects the animal's turning direction nearly independently of the texture and spatial layout of the environment. Our findings stress the significance of analyzing the performance of neuronal circuits under their natural operating conditions.