SSD prototype (via Edmond and Lily Safra Neuroscience Center)


Scientists from the Edmond and Lily Safra Neuroscience Center at the Hebrew University of Jerusalem have developed an algorithm that turns video, captured by a camera mounted on sunglasses, into sounds. The intent is to create a sensory substitution device (SSD) that allows congenitally blind people to perceive their surroundings via sounds. While testing their device, they were able to take images of the brain, which showed surprising and exciting news about the brain.



The system uses a laptop or a smartphone to process geometries captured on video and convert them into sounds. The example they give of this conversion is turning an oblique line (not parallel nor perpendicular) in to an increasingly high-pitched or increasingly low-pitched sound, presumably depending on what direction it is diverging. This same principle is used to convert more complex visuals and geometries into sound.



Patients testing the device have been able to distinguish between objects and can locate them or position them in space. Objects like houses, written letters and faces and even some facial expressions can be audibly perceived. They can also learn to read text by hearing the curvature of the letters and how they are strung together. All of this grants greater “visual” acuity than what is defined as blindness by WHO criteria.



Researchers from the ICM Brain and Bone Marrow Institute Research Center and NeuroSpin (CEA-Inserm) aided in testing this SSD. What they found in MRIs taken while patients used the system was remarkable. It was long believed that the visual cortex of the congenitally blind was never developed and that, after a certain point, it could not be rehabilitated even if the condition causing blindness was cured. However, the teams found that using this SSD stimulated the visual cortex, and it became active in congenitally blind patients, a testament to the brain’s plasticity. Furthermore, tests revealed that different parts of the brain activated when the user was presented different objects like faces or text. This confirms the theory that the brain innately categorizes different but very important objects and analyzes them separately.



Laurent Cohen from the ICM Research Center said, “these results suggest that it may be possible, with the right technology and rehabilitation, to ‘wake up’ certain areas of the brain and access certain aspects of the visual world, even after years, or even a lifetime of blindness.”



Little was said about the software used to achieve this conversion or when we could see it becoming a widely used form of therapy for blind patients. The results of this study were published in the November 8th issue of Neuron.