Brain

Prosopagnosia (Greek: "prosopon" = "face", "agnosia" = "not knowing"), also called face blindness, is a disorder of face perception where the ability to recognize faces is impaired, while other aspects of visual processing (e.g., object discrimination) and intellectual functioning (e.g., decision making) remain intact. The term originally referred to a condition following acute brain damage (acquired prosopagnosia), but a congenital or developmental form of the disorder also exists, which may affect up to 2.5% of the population.

The specific brain area usually associated with prosopagnosia is the fusiform gyrus, which activates specifically in response to faces. Thanks to this specialization, most people recognize faces much more effectively than they do similarly complex inanimate objects. For those with prosopagnosia, the ability to recognize faces depends on the less-sensitive object recognition system.

Though there have been several attempts at remediation, no therapies have demonstrated lasting real-world improvements across a group of prosopagnosics. Prosopagnosics often learn to use 'piecemeal' or 'feature by feature' recognition strategies. This may involve secondary clues such as clothing, gait, hair color, body shape, and voice. Because the face seems to function as an important identifying feature in memory, it can also be difficult for people with this condition to keep track of information about people, and socialize normally with others.

Prosopagnosia has also been associated with other disorders that are associated with nearby brain areas: left hemianopsia (loss of vision from left side of space, associated with damage to the right occipital lobe), achromatopsia (a deficit in color perception often associated with unilateral or bilateral lesions in the temporo-occipital junction) and topographical disorientation (a loss of environmental familiarity and difficulties in using landmarks, associated with lesions in the posterior part of the parahippocampal gyrus and anterior part of the lingual gyrus of the right hemisphere).

There are two types of prosopagnosia: acquired and congenital (developmental). Acquired prosopagnosia results from occipito-temporal lobe damage (See Etiologies and Affected Brain Areas) and is most often found in adults. This is further subdivided into apperceptive and associative prosopagnosia (See Types). In congenital prosopagnosia, the individual never adequately develops the ability to recognize faces.



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