08 December 2019

A Mathematical Model Understanding Vision

Researchers are creating a single mathematical model that unites years of biological experiments and explains how the brain produces elaborate visual reproductions of the world based on scant visual information. They have been building their model by incorporating one basic element of vision at a time. They’ve explained how neurons in the visual cortex interact to detect the edges of objects and changes in contrast, and now they’re working on explaining how the brain perceives the direction in which objects are moving. In lab experiments, researchers present primates with simple visual stimuli — black-and-white patterns that vary in terms of contrast or the direction in which they enter the primates’ visual fields. Using electrodes hooked to the primates’ visual cortices, the researchers track the nerve pulses produced in response to the stimuli. A good model should replicate the same kinds of pulses when presented with the same stimuli.


Currently they are working on adding directional sensitivity into their model — which would explain how the visual cortex reconstructs the direction in which objects are moving across your visual field. After that, they’ll start trying to explain how the visual cortex recognizes temporal patterns in visual stimuli. They hope to decipher, for example, why we can perceive the flashes in a blinking traffic light, but we don’t see the frame-by-frame action in a movie. At that point, they’ll have a simple model for activity in just one of the six layers in the visual cortex — the layer where the brain roughs out the basic outlines of visual impression. Their work doesn’t address the remaining five layers, where more sophisticated visual processing goes on. It also doesn’t say anything about how the visual cortex distinguishes colors, which occurs through an entirely different and more difficult neural pathway. While their model is far from uncovering the full mystery of vision, it is a step in the right direction.

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