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posted by Fnord666 on Sunday June 18 2017, @06:04PM   Printer-friendly
from the never-forget-a-face dept.

Scientists have reconstructed faces nearly perfectly by analyzing the activity of neurons in macaque brains:

[Using] a combination of brain imaging and single-neuron recording in macaques, biologist Doris Tsao and her colleagues at Caltech have finally cracked the neural code for face recognition. The researchers found the firing rate of each face cell corresponds to separate facial features along an axis. Like a set of dials, the cells are fine-tuned to bits of information, which they can then channel together in different combinations to create an image of every possible face. "This was mind-blowing," Tsao says. "The values of each dial are so predictable that we can re-create the face that a monkey sees, by simply tracking the electrical activity of its face cells."

Previous studies had hinted at the specificity of these brain areas for targeting faces. In the early 2000s, as a postdoc at Harvard Medical School, Tsao and her collaborator electrophysiologist Winrich Freiwald, obtained intracranial recordings from monkeys as they viewed a slide show of various objects and human faces. Every time a picture of a face flashed on the screen, neurons in the middle face patch would crackle with electrical activity. The response to other objects, such as images of vegetables, radios or even other bodily parts, was largely absent.

Further experiments indicated neurons in these regions could also distinguish between individual faces, and even between cartoon drawings of faces. In human subjects in the hippocampus, neuroscientist Rodrigo Quian Quiroga found that pictures of actress Jennifer Aniston elicited a response in a single neuron. And pictures of Halle Berry, members of The Beatles or characters from The Simpsons activated separate neurons. The prevailing theory among researchers was that each neuron in the face patches was sensitive to a few particular people, says Quiroga, who is now at the University of Leicester in the U.K. and not involved with the work. But Tsao's recent study suggests scientists may have been mistaken. "She has shown that neurons in face patches don't encode particular people at all, they just encode certain features," he says. "That completely changes our understanding of how we recognize faces."

Also at Singularity Hub and The Guardian:

Professor Rodrigo Quian Quiroga, a neuroscientist at the University of Leicester who was not involved in the work, described it as "quite a revolution in neuroscience". "It's solving a decades-long mystery," he added.

The puzzle of how the brain identifies a familiar face dates back to the 1960s, when the US neuroscientist, Jerry Lettvin, suggested that people have hyper-specific neurons that respond to specific objects, a notion that became known as "grandmother cells", based on the idea that you have a specific neuron that would fire on seeing your grandmother.

More recently scientists found "face patches", clusters of neurons that respond almost exclusively to faces, but how recognition was achieved had remained a "black box" process. In the absence of proof otherwise, the grandmother model continued to appeal because it tallied with the subjective "ping" of recognition we experience on seeing a familiar face.

"This paper completely kills that," said Quian Quiroga.

The Code for Facial Identity in the Primate Brain (DOI: 10.1016/j.cell.2017.05.011) (DX)

Original Submission

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  • (Score: 2) by Unixnut on Sunday June 18 2017, @09:49PM (3 children)

    by Unixnut (5779) on Sunday June 18 2017, @09:49PM (#527607)

    "Jennifer Aniston elicited a response in a single neuron"

    They finally found the "Horny switch"! All that brain matter abstracting away, and it actually boils down to one neuron for the important stuff :-)

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  • (Score: 0) by Anonymous Coward on Sunday June 18 2017, @10:06PM (1 child)

    by Anonymous Coward on Sunday June 18 2017, @10:06PM (#527616)

    White-bread Jennifer doesn't do the nasty like Angelina does.

    • (Score: 0) by Anonymous Coward on Monday June 19 2017, @01:31AM

      by Anonymous Coward on Monday June 19 2017, @01:31AM (#527676)

      2 neurons for Angelina?

  • (Score: 2) by nishi.b on Monday June 19 2017, @07:36AM

    by nishi.b (4243) on Monday June 19 2017, @07:36AM (#527798)

    Seriously, the most amazing thing about Quiroga's work was that he was able to record a cell that responded to the name of the actress displayed on the screen, her face, her voice, so a cell that reacted to multiple types of input (audio, video, text, image) for the same concept.
    This was in the hippocampus that's well know for memory formation. His conclusion was not that we had one cell for each concept, or that it reacted only to this concept (even though he tried to have it react to multiple types of stimuli) but that from the data he had to present to the subject, this cell (and probably others he could not record) were reacting to this concept. In the paper he also speaks about cells that react to pictures of buildings, but it was funnier to publish on the Jennifer Aniston cell !

    In this case, I won't say I am really surprised as we already know that lower-level visual areas of the brain react to lower level features (straight lines, according to their direction for example), and the "face" area of the cortex is also well-know from patients with brain lesions.
    This looks like what you get in artificial neural networks : advanced feature extraction. This still does not contradict the fact that you can have "grandmother cells" that will identify who it can be from the high-level extracted features of the face, probably in another part of the brain.

    Disclaimer : I met Quiroga once and worked in neuroscience labs doing fMRI, EEG, MEG and implanted electrophysiology recordings in humans and primates.