ENTRAIN VISION early-stage researchers will conduct their individual research projects across multiple disciplines including neuroscience, vision, psychophysics, genetic, electronic, bio-engineering, neuromorphic hardware and computational modelling.

Objectives:
– Demonstrate functional efficacy of whole diamond visual prostheses ex vivo, in vivo;
– Assess safety and stability of the diamond visual implants.

Expected Results:
– Detailed characterization of the functional properties for the doped diamond electrodes as measured in vitro on an isolated retina recorded on a multielectrode array.
– Proof of concept for the in vivo activation of neurons on the visual system at the retinal and cortical levels.
– Stability of the implant in vivo by several months of in vivo monitoring and subsequent ex vivo characterization.
– Safety of the implant by histological examination of the tissues following several months in vivo.

Most inherited retinal dystrophies display progressive photoreceptor cell degeneration leading to severe visual impairment, and no cure is currently available. Optogenetic reactivation of retinal neurons mediated by adeno-associated virus gene therapy has the potential to restore vision regardless of patient specific mutations. Channel rhodopsin (ChR2) has been successfully expressed in retinal ganglion cells and light sensitivity was restored with photo stimulation of those cells. A major issue when directly activating the ganglion cell is that it bypasses the natural processing performed by the multiple layers of a normal retina. To reproduce retinal processing as close as possible to natural vision, other retinal cell types can be targeted with optogenetic protein. Here we will develop new modelling strategies and use them both in normal and reactivated retinas to understand the difference between normal and reactivated processing. We will also build on several datasets where different cell types have been targeted and use these new modelling tools to understand what processing can be restored depending on which cell type is targeted. This will be a key step to understand how restore an effective vision to blind patients.

Objectives:
– Emulate prosthetic vision in a virtual immersive multi-sensorial environment.
– Assess different designs of new prostheses in healthy subjects.

Expected Results:
– Design Virtual reality scenari that are common in daily life.
– Measure behavioral performances of healthy subjects while emulating prosthetic vision with different resolution, visual field and electrode distribution.
– Propose new protocols for assessing the benefit of visual prostheses in patients.

Objectives:
– Apply optical tweezers to retinal cell separation.
– Dielectric characterization of retinal cells.
– Separation of retinal cells for cell transplantation and optogenetic therapy.

Expected Results:
– Protocols for label-free, contactless retinal cells characterization / selection.
– Production of purified cell types for cell transplantation.
– Preservation of purified retinal cell types.

Objectives:
– Evaluate the spatial, temporal and contrast sensitivity of spatio-temporally patterned;
optogenetically and electrically stimulated retinal circuits in blind ex vivo retina;
– Develop object encoding strategies for optogenetic and for electrical stimulation.

Expected Results:
– Characterization of the spatio-temporal and contrast sensitivity responses in blind retinas upon optogenetic and electric activation using multi-electrode array recording.
– Responses for patterned stimuli to both optogenetic and electrical approaches in blind retina.
– Object encoding strategies validated on blind retinas.

Objectives:
– Characterize the emergence of neuroprotective markers induced by means of sustained electrical stimulation of retinal cell.
– Characterize the neuroprotective effect of electrical stimulation on the survival rate of the degenerating photoreceptors (role of retinal pigment-epithelium).
– Co-application of electrical stimulation and drugs on mouse retina.
– Comparison of the electro-stimulation induced neuroprotective effect on mouse retina (ex vivo) with human retinal organoids (iPSC) or in mouse eyes (in vivo).

Expected Results:
– Understand the neuroprotective effect of neuronal electrostimulation in different RD animal models at functional, physiological and histological level elicited by TES at early stages and late stages of the RD.
– Identification of dose-response dependency in order to define which gene expression needs to be modulated to provide a neuro-protective effect
– Elucidation of the key pathways of primary and secondary modulators after acute application of electrical stimulation: MAP-Kinase-Pathway, IGF-1, FGF-2, Bcl-2, CNTF, BDNF and Bax.
– Enhancement of the efficiency factor of the electrical stimulation mediated neuroprotection by a compounds, e.g. antiapoptotic factor.

Objectives:
– Characterize the retinal ouput at different disease states in a model of retinal disease.
– Correlate the retinal output to the animal behavior in the water mazer.

Expected Results:
– Definition of the limit in ganglion cell output to trigger visual perception;
– Conclusions for expected visual perception during visual restoration based on the restored retinal output.

Objectives:
– Quantify the visual performance of various mouse models with unprecedented resolution;
– Correlate behavior response to retinal ganglion cell measurements;
– Understand the functional implications of retinal circuit mechanisms in healthy and diseased animal models.

Expected Results:
– Define behaviour dysfunction according to retinal diseases;
– Establish a rule between ganglion cell function and animal behaviour;
– Break new frontiers in understanding both the functional implications as well as the mechanistic basis of retinal computations in healthy and diseased visual systems.

Objectives:
– Implement bioinspired algorithms to maximize meaningfull information in a visual scene;
– Develop such algorithm for patients with partial visual loss through augmented vision systems.

Expected Results:
– Developmet of different image enhancement techniques using parallel architectures in either mobile GPUs of FPGAs, to cover different power and/or speed requirements.
– Validation of these techniques in patients suffering from either central or peripheral vision loss.
– Implementation of a bioinspired visual encoder optimized for cortical visual neuroprosthesis.

Objectives:
– Model patterned micro-stimulations expected from an cortical visual prosthesis.
– Develop new strategies to provide functionally meaningful information to a cortical visual neuroprosthesis that can be specifically tailored for every patient’s individual needs.
– Define the multimodal plasticity changes occuring following the loss of sight to improve the success of visual restoration.

Expected Results:
– Characterization of the degree of cross-modal plasticity in blind patients using Transcranial Magnetic Stimulation (TMS), Magnetic Resonance Imaging (MRI), functional Magnetic Resonance Imaging (fMRI), Diffusion Tensor Imaging (DTI) and Magnetic Resonance Spectroscopy) according to the level of blindness.
– Protocols for testing visual perception with cortical prosthesis.
– Algorithms to design complex stimulating patterns through the multiple microelectrodes of a cortical prosthesis.

Objectives:
-Embed a model of a cortical prosthetic device in existing models of early visual system.
– Calibration of simulations against in-vivo cortical data obtained inside the consortium.
– Understand how patterned stimulation interacts with the activity dynamics in neural circuitry.
– Formulate recommendations for specifications of future visual implants stimulation protocols.

Expected Results:
– Simulation software capable of predicting the outcome of stimulation in cortex in biologically detailed model of retino-thalamo-cortical circuitry.
– Demonstration of adherence of the modelled optogenetic stimulation outcomes to corresponding data from in-vivo experiments.
– Detailed analysis of neural dynamics in retina, LGN and V1 under various configurations of optogenetic stimulation.
– Draft of specifications of implant hardware and associated stimulation protocols that would be optimal at inducing cortical activity patterns analogous to those due to normal vision.

Objectives:
-Develop neural data metrics for validating the quality of optogenetic stimulation.
-Develop machine learning based around specialzed DNN architectures for learning the encoding scheme of the visual input to replicate encoding at the level of retina, LGN and V1.
-Ensure operability of the encoding schemes determined in 2 within the constraints of the prosthetic device hardware.

Expected Results:
-Specification of analysis protocols for determining the quality of optogenetic stimulation.
– Learned mapping from the visual stimulus to the retina, LGN or visual cortex with all transformations from the prosthetic input hardware (camera) to the implanted LED array.
– A ready-to-use implementation of the stimulation protocols on the specialized low-powered hardware of the prosthetic device.

Objectives:
– Development of new potent and persistent membrane-targeted azobenzene-based compounds for photoexcitation.
– Validation of the new photoswitch for visual restoration.
– Production of photoswitch delivery system.

Expected Results:
– Characterization of the mechanism of action of azobenzene-based compounds.
– Characterization of the new photoswitch effects in neurons and retinal explants.
– Setup of an efficient in vivo delivery system.
– Proof of concept in in vivo animal models of retinal diseases.

Objectives:
– Validation of microinjectable polymeric nanoparticles as high-resolution and minimally invasive retinal prosthetic devices.
– Validation of potent and persistent membrane-targeted azobenzene-based compounds for visual restoration.
– Demonstration of safety and efficacy of the photosensitive polymeric nanoparticles and membrane-targeted azobenzene compounds.

Expected Results:
– Characterization of the light-dependent effects of azobenzene photoswitches and polymeric nanoparticles in neurons and retinal explants.
– Proof of concept (efficacy and safety) in an in vivo animal model of retinal diseases.

Objectives:
– Develop a set of protocols to evaluate the therapeutic benefit of vision restoration using standardized daily-life tasks (reading, locomotion, spatial orientation, posture …)
– Propose to regulatory authorities (e.g., FDA, EMEA, ANSM) new objective assessment criteria for the therapeutic benefit of visual restoration in clinical studies.

Expected Results:
– Identification of the behavioral markers of performance in low vision patients using the study of postural, sensorimotor and oculomotor changes in the daily-life tasks (e.g. reading, locomotion, visual search, spatial orientation and driving).
– A standardized experimental platform to measure, extract and analyze behavioral markers using (1) functional tests, (2) quality of life questionnaires, (3) performance in standard tasks of daily living, and (4) actual activity in daily life (actimetry and connected objects).
– Define the acceptability and sensitivity of this platform for therapeutic benefit of vision restoration.
– Grade tests to define their availability among clinical investigation centers, contract clinical research organizations and health professionals for standardized and multicentric assessments.