The Early Time Course of Compensatory Face Processing in Congenital Prosopagnosia

BACKGROUND: Prosopagnosia is a selective deficit in facial identification which can be either acquired, (e.g., after brain damage), or present from birth (congenital). The face recognition deficit in prosopagnosia is characterized by worse accuracy, longer reaction times, more dispersed gaze behavior and a strong reliance on featural processing. METHODS/PRINCIPAL FINDINGS: We introduce a conceptual model of an apperceptive/associative type of congenital prosopagnosia where a deficit in holistic processing is compensated by a serial inspection of isolated, informative features. Based on the model proposed we investigated performance differences in different face and shoe identification tasks between a group of 16 participants with congenital prosopagnosia and a group of 36 age-matched controls. Given enough training and unlimited stimulus presentation prosopagnosics achieved normal face identification accuracy evincing longer reaction times. The latter increase was paralleled by an equally-sized increase in stimulus presentation times needed achieve an accuracy of 80%. When the inspection time of stimuli was limited (50 ms to 750 ms), prosopagnosics only showed worse accuracy but no difference in reaction time. Tested for the ability to generalize from frontal to rotated views, prosopagnosics performed worse than controls across all rotation angles but the magnitude of the deficit didn't change with increasing rotation. All group differences in accuracy, reaction or presentation times were selective to face stimuli and didn't extend to shoes. CONCLUSIONS/SIGNIFICANCE: Our study provides a characterization of congenital prosopagnosia in terms of early processing differences. More specifically, compensatory processing in congenital prosopagnosia requires an inspection of faces that is sufficiently long to allow for sequential focusing on informative features. This characterization of dysfunctional processing in prosopagnosia further emphasizes fast and holistic information encoding as two defining characteristics of normal face processing

Deficits in Long-Term Recognition Memory Reveal Dissociated Subtypes in Congenital Prosopagnosia

The study investigates long-term recognition memory in congenital prosopagnosia (CP), a lifelong impairment in face identification that is present from birth. Previous investigations of processing deficits in CP have mostly relied on short-term recognition tests to estimate the scope and severity of individual deficits. We firstly report on a controlled test of long-term (one year) recognition memory for faces and objects conducted with a large group of participants with CP. Long-term recognition memory is significantly impaired in eight CP participants (CPs). In all but one case, this deficit was selective to faces and didn't extend to intra-class recognition of object stimuli. In a test of famous face recognition, long-term recognition deficits were less pronounced, even after accounting for differences in media consumption between controls and CPs. Secondly, we combined test results on long-term and short-term recognition of faces and objects, and found a large heterogeneity in severity and scope of individual deficits. Analysis of the observed heterogeneity revealed a dissociation of CP into subtypes with a homogeneous phenotypical profile. Thirdly, we found that among CPs self-assessment of real-life difficulties, based on a standardized questionnaire, and experimentally assessed face recognition deficits are strongly correlated. Our results demonstrate that controlled tests of long-term recognition memory are needed to fully assess face recognition deficits in CP. Based on controlled and comprehensive experimental testing, CP can be dissociated into subtypes with a homogeneous phenotypical profile. The CP subtypes identified align with those found in prosopagnosia caused by cortical lesions; they can be interpreted with respect to a hierarchical neural system for face perception

Prosopagnosie (syn. Gesichtsblindheit) – Berichte von Betroffenen

Menschen mit Prosopagnosie, syn. Gesichtsblindheit, können Andere am Gesicht allein nicht wiedererkennen. In spontan zugesandten Berichten von Betroffenen wird aus sehr unterschiedlichen Perspektiven die Problematik im Alltag geschildert. Sie dokumentieren die Vielfalt aber vor allem auch die große Übereinstimmungen der Symptomatik. Das Entwickeln von zahlreichen kompensatorischen Strategien, die vielen typischen Anekdoten, sowie das häufige Fehlen von inneren Bildern beschreiben übereinstimmend das subjektive Empfinden einer Prosopagnosie

Acquired and hereditary prosopagnosia in history, fiction literature, biographies, and live celebrities of the present

Prosopagnosia (syn. face blindness) describes an inborn or acquired deficiency of face perception. In probands with this anomaly the ability to recognize even familiar faces is impaired, whereas faces expressing emotions, attractiveness and gender are clearly seen. In contrast to the acquired form, which is easily diagnosed by the sudden loss of a skill, the congenital form is mostly overlooked. Nevertheless, prosopagnosia is very common and almost always hereditary. Once alerted to this phenomenon it is found by chance – sometimes hidden - in a variety of sources as in autobiographies, poems, celebrities in live radio/TV programmes, and even one’s own close friends. Almost all of the subjects think their problem is unique, and in cases with the very frequent hereditary form, nearly all of the affected individuals were not aware of other impaired first-degree relatives

Hereditary prosopagnosia in self reports

People who suffer from prosopagnosia, syn. face blindness are unable to recognize others solely by their face. Reports by those affected picture the problematic nature from very different perspectives in every day life. Not only the variety, but most notably the wide resemblance of the symptoms is documented. The generation of numerous compensatory strategies, the many typical anecdotes, and the frequent deficiency of inner images concordantly describe the subjective sensibility of prosopagnosia

An intronic COL1A1 Sp1-Polymorphism but not Vitamin D Receptor Gene Polymorphisms Relates to the Phenotypic Expression of Osteogenesis imperfecta

This is the first observation of a polymorphism associated with the severity of clinical manifestation in Osteogenesis imperfecta (OI). The results are consistent with a polygenic quantitative trait model in which OI albeit a monogenic autosomal dominant disease can be modified by additional risk factors. In our collection the severe cases of OI are significantly associated with a COL1A1 Sp1 polymorphism, an association initially observed in postmenopausal women with osteoporosis. In both studies a G → T polymorphism in the same Sp1 motif is found rather in the clinically severe cases. As diverse vitamin D receptor (VDR)-polymorphisms are one of the strongest risk factors of osteoporosis this prompted us to examine a putative association in our OI collection. However, we could not find a correlation of the severity of OI with any of the four polymorphisms (BsmI, ApaI, and TaqI RFLPs). We conclude that the COL1A1 Sp1 polymorphism is of high prognostic value in OI individuals homozygous for the T allele