The Brain

Map For Reading Faces Identified In The Human Brain

January 20, 2016 | by Ben Taub

The neurons that recognize different facial features are spread out in a similar pattern to the physical distribution of these features on an actual face.
Photo credit: The neurons that recognize different facial features are spread out in a similar pattern to the physical distribution of these features on an actual face. Maridav/Shutterstock

The ability to recognize faces is an important social skill, enabling us to distinguish our friends from our enemies while at the same time facilitating non-verbal communication in the form of facial expressions. Yet while most of us simply take this ability for granted, the reality is it wouldn’t be possible at all without the appropriate neurological infrastructure.

According to a recent paper that appeared in the journal Cortex, facial recognition may be regulated via neurons that are arranged like a “map” of a face, with each section responsible for identifying a particular facial feature.

The researchers behind the study have labeled this phenomenon “faciotopy,” and arrived at their findings after devising an experiment to investigate whether retinotopy could be used to explain how faces are recognized by the brain. This refers to the mapping of visual input onto particular neurons, which are arranged in a particular pattern so as to mirror the various features of the item being viewed.

To conduct this research, the team presented volunteers with images of isolated facial features, such eyes, ears, noses, and mouths. Using functional magnetic resonance imaging (fMRI), they measured participants’ brain activity in order to determine which neurons were stimulated by each image.

In particular, they focused on the occipital face area (OFA) and the fusiform face area (FFA), both of which are located on the cortical surface and have been associated with facial recognition in the past. For instance, previous studies have shown the subjects’ ability to distinguish between different faces is disrupted when certain areas of the OFA are electrically stimulated, while others have revealed that this brain region is activated more strongly by images of complete faces compared to those with blacked-out features.

Results revealed that the “OFA, and to a lesser degree FFA, showed evidence for faciotopic organization,” with different “patches” of neurons being activated depending on which facial feature was being presented. Furthermore, “the cortical distances between the feature patches reflected the physical distance between the features in a face.” In other words, the neurons responsible for identifying different facial features are positionally arranged in the same way as these features occur on a face.

Faciotopy may explain why we are able to recognizes faces even when they aren't real. Nickola_Che/Shutterstock

Explaining their findings, the study authors propose that the human brain may have evolved to include a faciotopic map since “faces have particular perceptual significance and have prototypical configuration of features.” 

Commenting on this research, other experts have proposed that faciotopy in the brain may explain why we so readily see faces in inanimate objects, even when they aren’t really there. For instance, images of shadows cast by a rock formation on Mars caused a stir when they were released by NASA in 1976, as they appeared to resemble an eerie face. Other famous examples include this kettle that bears an uncanny resemblance to a certain 20th-century tyrant, and this tub of butter that looks like Donald Trump.

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