Not Just a Sheet of Light SensorsNew research out of Germany is helping to pinpoint details of how the mammalian retina converts incoming light into digital signals which ultimately make their way to the brain. Before the information is shipped off to the brain, however, it undergoes massive processing which, among other things, helps to extract features present in the incoming image. It is so complex that we are still a long way from understanding how it all works. The new research, as one report explains, “show that the retina is by no means as well understood as is commonly believed.” We have discussed some of the complexities of converting the incoming light into digital signals to be sent to the brain here, here and here. There is no doubt much yet to learn about this incredible image processing capability, but what we do know indicates it is profoundly sophisticated. As the report explains:
The retina in our eyes is not just a sheet of light sensors that – like a camera chip – faithfully transmits patterns of light to the brain. Rather, it performs complex computations, extracting several features from the visual stimuli, e.g., whether the light intensity at a certain place increases or decreases, in which direction a light source moves or whether there is an edge in the image. To transmit this information reliably across the optic nerve - acting as a kind of a cable - to the brain, the retina reformats it into a succession of stereotypic action potentials – it “digitizes” it.
Feature extraction is an important technology these days, with all kinds of applications. Engineers have been working hard at developing such techniques for years. As usual, nature provides examples of astonishing precision and efficiency.