Mental Health & Neurology

AXA Chairs


Unlocking the mystery of how the brain sees : paving the way for visual impairment cures

The brain reconstructs the visual world around us too fast for us to even realize. In that instant, signals are sent from neuron to neuron in an intricate, and still partly mysterious, arrangement of connections across the brain’s visual circuits. As a result of this complexity, numerous disorders can affect vision; these can be caused by genetic abnormalities, congenital problems, disease, trauma or ageing. Globally, it is estimated that 285 million people are visually impaired, amongst who 39 million are blind. As a result of demographic growth and ageing populations, the World Health Organization warns these figures may double by 2025.
The recipient of an AXA Chair at Sorbonne Université in Paris, Dr. Valentina Emiliani, a CNRS research director, is leading a pioneering research project aimed at developing advanced optical methods for the investigation of the visual circuits functioning. The overarching aim of the program is to shed light on the mechanisms and dynamics involved in the regulation of visual circuits, so as to pave the way for new strategies for vision restoration. « The Chair’s project comprises a technological and a biological part », Dr. Emiliani specifies « and this is the reasons why my team of researchers is composed of both physicists and neurophysiologists.»

3D holographic restitution of the brains’s activity with single-neuron resolution.

Working together, they have improved current state-of-the-art microscopy to allow them, not only to trace a single neuron’s activity, but also to manipulate them using optogenetics. « The ability to perturb or manipulate the flow of excitation and inhibition is essential for elucidating causal relationships between neurons, and thus their role in health and disease, says the holder of the Chair. To achieve this, we’ve reflected on how to use sculpted light and optogenetics to turn on and off one or multiple neurons at a time with single cell precision and millisecond temporal precision»

What they have come up with is a holographic microscope, which can send targeted light into a brain slice, or a mouse’s brain. This approach combined with optogenetics enables to precisely control and manipulate the activation of neurons in a brain circuits. « We’re going to use this new technology to investigate the mechanisms regulating connectivity and signal processing across the main visual pathways (retina, lateral geniculate nucleus, primary visual cortex) with unprecedent spatial precision and temporal resolution. ». The long-term prospective is to bring to light the complete designs and global architecture of vision, reaching «full visual circuit reverse engineering», as the project puts it. « The technology that we will demonstrate, says Dr. Valentina Emiliani, will ultimately open up the possibility to “play the brain like a piano”, a dream that will enable scientists to understand how a specific pattern of activity contributes to brain computations, and vision processing ».



Sorbonne University





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