Prosopagnosia, the inability to recognize human faces

It is very easy to believe that our visual system works by giving us reliable information about the outside environment and that the brain is just a receptacle for these images which tell us what is going on in the world. However, the truth is that our nervous system plays a very active role in processing this information so that it is consistent and meaningful.

the prosopagnosi it is a phenomenon which serves to remind us of this fact.

What is prosopagnosia?

It is, in short, a failure of our nervous system the consequence is that anyone who experiences it is not able to recognize human faces. This means that although he has perfect eyes and is able to put together all the visual information relating to a person’s face, he is not able to detect the patterns that make that face unique. . In short: we see the face but we don’t recognize it.

Prosopagnosia is a type of visual agnosiaAs there are several classes of neurological disorders in which what we see is not normally recognized by the brain. It is also one of the most well-known types of agnosia thanks, among other things, to the recently deceased neurologist Oliver Sacks, who spoke about his experience with visually impaired patients in one of his most famous books: The Man to whom he took his wife for a hat.

How do people with prosopagnosia perceive faces?

People with prosopagnosia perceive faces as a somewhat blurry image and are able to notice the existence of typical facial organs (eyes, nose, etc.) but not their exact location as a whole. However, there are cases in which they can recognize certain features of the face of a few people, or better roughly perceive the faces of certain groups (people of a certain gender, or with Asian features, etc.).

Prosopagnosi that does not make the task of recognizing someone impossible, As people with this neurological disorder can identify the rest by the way they walk, their clothes, their hair …

What are the causes of prosopagnosia?

Prosopagnosia can be due to injuries in specific areas of the brain, but it can also be a condition that one is born with. It is believed that the part of the brain that functions abnormally in people with this disorder is that of the spindle gyrus, an area of ​​the cerebral cortex located in the temporal lobe near the temples. Thanks to the fusiform rotation, we are extremely sensitive to all the subtleties that a human face can contain, and also thanks to it we have an unprecedented propensity to see faces in all kinds of things, including inanimate objects (to these “illusions” called paridolia).

When the spindle or neural networks that connect this area to other parts of the brain are functioning abnormally, this can result in an inability to detect the visual patterns necessary to “see” a face as a whole..

The brain has mechanisms to overcome this condition

However, in a sense, the brain obtains visual information from faces, so other areas of the nervous system can process that information subconsciously. This explains why people with prosopagnosia show emotional activation when they see the faces of close people (their mother, friends, etc.), even if they do not consciously recognize them. This is because even though the rotation of the spindle does not work well, some of the visual information is processed in parallel by the limbic system, which is responsible for eliciting emotional responses.

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