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Multisensory Navigation: Harnessing the Power of Multisensory Processing Optogenetic Stimulation to Aid The Blind

Periodic Reporting for period 1 - MultiNav (Multisensory Navigation: Harnessing the Power of Multisensory Processing Optogenetic Stimulation to Aid The Blind)

Reporting period: 2015-05-01 to 2017-04-30

In Europe 30M people are visually impaired (VI), 2.5M of which are entirely blind. Despite many efforts on the societal level, VIs are still ‘left in the dark’, when it comes to independent navigation. Neuroscience has the long-term potential to provide brain-prostheses, which circumvent damaged parts of the visual system. In the present action, we investigated how spatial information can assist VIs during navigation by non-invasive and invasive information delivery. We made use of sensory substitution and optogenetic stimulation to investigate these questions in an animal model of navigation in the dark. Hence, our research contributed to develop future navigation systems for the blind, either non-invasively and invasively.
Concretely the objectives of the action were to (1) develop an experimental system for rapid position-to-audition/optical signal feedback, (2) test the effectiveness of auditory feedback of target distance in an animal experiment, and then (3) substitute an optical signal for the acoustic signal in the auditory part of the brain. The last objective has the longterm goal of developing a future invasive prosthesis for the visually impaired. The first two objectives were achieved, whereas the third has been started and is still ongoing. We are in contact with both user groups and applied research institutions to support the development of assistive devices.
During the action we developed several key technology platforms and conducted two sets of experiments. The technology platforms were necessary to precisely quantify the animal behaviour and assess, whether an improvement in performance is achieved during sensory substitution.
The first technology platform allowed rapid sensing of the animal position. This position was then converted into an acoustic or an optical signal signal played back to the animal (in the dark!). The animals learned to use this acoustic signal to improve their ability to cross an obstacle, when their whiskers were removed. Hence, sensory substitution could be established in this way in the mouse.
Next, we performed neural recordings from the auditory part of the brain of the mouse. These recordings could only be performed due to a second technology platform we developed, which allows to record from the behaving animal, while monitoring its behavior and whiskers at the same time. This new implant was also successfully developed and deployed in multiple animals.
Finally, we provided optical signals to the brain of mice whose brains were modified to be receptive to light. During this process we encountered technical difficulties, which we are currently working to resolve. These difficulties are related to the interaction of the light with scaring tissue, which reduced the light intensity below a level that can stimulate the brain. We are currently using improved implant designs and stronger light-sources to overcome the problem.
Throughout the research phase we have published 5 publications on related topics, and we currently preparing two additional publications, one on the sensory substitution results and one on the new technology platform. In addition we have presented our research at internal and external meetings and conferences.
We have established a rapid and automatized test-platform, which enables future research into this question in our group. The experimental tools developed to recorded from the behaving mouse from auditory cortex are general and will equally be enabling for a large range of projects in our and other groups. Further, we have demonstrated that sensory substitution between the auditory and touch domain is possible, and provides a useful platform for further investigating sensory substitution for the visually impaired. While the final objective has not been achieved yet, its societal impact will be greatest, and we therefore remain committed to achieving this goal in the near future.
Overview of the Project Results