How the Brain’s Face Code Might Unlock the Mysteries of Perception - ScientificAmerican.com
Doris Tsao mastered facial recognition in the brain. Now she’s looking to determine the neural code for everything we see
De moeite waard om helemaal eens door te nemen maar hier heb je wat snippets om je honger aan te wakkeren;
A cell’s rate of firing would ramp up according to how extreme the feature is, a property known as ramp-shaped tuning that turned out to be fundamental for face coding. A cell responding to the distance between two eyes, for example, might fire slowly in response to close-set eyes, but rapidly to ones set farther apart.
To investigate how the IT cortex might be encoding full faces from this information, Tsao realized that every face could be created by mixing the most important dimensions of ‘faceness’, such as how pointy a nose is, how eyes are set or complexion. She and her postdoc Steven Le Chang identified the 50 dimensions that varied most across faces—25 for shape and 25 for appearance—and created a set of 2,000 face images in which the value of all 50 dimensions was known. They flashed these images in front of the monkeys while measuring responses from 205 neurons in two face patches. The code started to reveal itself.
Cells in the more superficial patch tended to be tuned to shape dimensions, whereas many of those located deeper in the IT cortex responded to appearance dimensions.
Tsao and Chang could predict how the neurons would fire on the basis of the dimensions of any face, and they could even reconstruct a face just from the firing patterns of these cells
Om even te duiden hoe fucking amazing dit is; ze kunnen al langer vage filmpjes renderen van je dromen (yes really) in brede lijnen zie je dan de vorm van de objecten die je die nacht tijdens je slaap bezochten... Met dit onderzoek wordt in grote lijnen het gezicht ingevuld en weet men veel duidelijker wie verantwoordelijk is voor je natte droom.