Discover 1-2

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54 DISCOVERMAGAZINE.COM

LEFT: OLEG SENKOV/SHUTTERSTOCK. RIGHT: COURTESY OF DORIS TSAO

I Can See What

You’ve Seen

❯

BACK IN THE 19TH

CENTURY, a French

criminologist named

Alphonse Bertillon invented

a technique for recognizing

repeat offenders by precisely

measuring convicts’ facial features.

Fingerprinting eventually

supplanted his system,

but new research done

on macaques shows

primate brains can

naturally keep

track of faces

thanks

to a

kind of bertillonage.

The discovery, reported in June

in Cell, completely breaks with

the standard model of facial

recognition, which claims each

face you recognize is represented

by a single neuron (one cell firing

when you see your grandmother,

another when you see

Jennifer Aniston).

Instead, Caltech

neuroscientist Doris

Tsao showed that

individual primate

neurons respond to

specific facial qualities,

such as bone shape and

skin color.

Inserting electrodes into

the brains of two macaques,

Tsao worked out which aspects

of a face were mapped onto

each neuron. Then she validated

her findings by showing the

macaques additional faces, and

accurately reconstructing what

they’d seen using only neural

recordings.

Tsao predicts that, with

advances in human brain-

monitoring technology, “the

ability to decode faces by

neuronal activity can be used in

forensics, such as reading out a

criminal’s face from a witness’

mind.” Are you watching,

Monsieur Bertillon?

 JONATHON KEATS

Researchers had macaques look

at faces (left column), while

recording electrical activity from

205 of the monkeys’ neurons.

Scientists then used that data to

reconstruct those faces (right).

Actual faces Predicted faces