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Face recognition is important for both visual and social cognition. While prosopagnosia or face blindness has been known for seven decades and face-specific neurons for half a century, the molecular genetic mechanism is not clear. Here we report results after 17 years of research with classic genetics and modern genomics. From a large family with 18 congenital prosopagnosia (CP) members with obvious difficulties in face recognition in daily life, we uncovered a fully cosegregating private mutation in the MCTP2 gene which encodes a calcium binding transmembrane protein expressed in the brain. After screening through cohorts of 6589, we found more CPs and their families, allowing detection of more CP associated mutations in MCTP2. Face recognition differences were detected between 14 carriers with the frameshift mutation S80fs in MCTP2 and 19 noncarrying volunteers. Six families including one with 10 members showed the S80fs-CP correlation. Functional magnetic resonance imaging found association of impaired recognition of individual faces by MCTP2 mutant CPs with reduced repetition suppression to repeated facial identities in the right fusiform face area. Our results have revealed genetic predisposition of MCTP2 mutations in CP, 76 years after the initial report of prosopagnosia and 47 years after the report of the first CP. This is the first time a gene required for a higher form of visual social cognition was found in humans., Competing Interests: Conflicts of interest. The author(s) declare no conflict of interest., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Genetics Society of America. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Congenital Prosopagnosia (CP) is an innate impairment in face perception with heterogeneous characteristics. It is still unclear if and to what degree holistic processing of faces is disrupted in CP. Such disruption would be expected to lead to a focus on local features of the face. In this study, we used binocular rivalry (BR) to implicitly measure face perception in conditions that favour holistic or local processing. The underlying assumption is that if stimulus saliency affects the perceptual dominance of a given stimulus in BR, one can deduce how salient a stimulus is for a given group (here: participants with and without CP) based on the measured perceptual dominance. A further open question is whether the deficit in face processing in CP extends to the processing of the facial display of emotions. In experiment 1, we compared predominance of upright and inverted faces displaying different emotions (fearful, happy, neutral) vs. houses between participants with CP (N = 21) and with normal face perception (N = 21). The results suggest that CP observers process emotions in faces automatically but rely more on local features than controls. The inversion of faces, which is supposed to disturb holistic processing, affected controls in a more pronounced way than participants with CP. In experiment 2, we introduced the Thatcher effect in BR by inverting the eye and mouth regions of the presented faces in the hope of further increasing the effect of face inversion. However, our expectations were not borne out by the results. Critically, both experiments showed that inversion effects were more pronounced in controls than in CP, suggesting that holistic face processing is less relevant in CP. We find BR to be a useful implicit test for assessing visual processing specificities in neurological participants., (© 2024. The Author(s).)

Prosopagnosia or 'face blindness' is the inability to recognise people's faces. There are two types: congenital or developmental prosopagnosia, which is the most common, and acquired prosopagnosia, which may occur secondary to brain tumours, stroke or other brain disorders. The authors of this article explored if mask wearing as a result of the restrictions imposed by the coronavirus disease 2019 (COVID-19) pandemic may affect social and developmental outcomes in children, including the development of prosopagnosia. Limited research on this topic is available and, although some relevant publications were found, no definitive evidence of mask-induced prosopagnosia in children was identified. However, nurses should be aware of this issue and discuss coping strategies to support children with the condition. Longitudinal studies on outcomes in children from different age groups who grew up during the COVID-19 pandemic will provide further insight., Competing Interests: None declared, (© 2023 RCN Publishing Company Ltd. All rights reserved. Not to be copied, transmitted or recorded in any way, in whole or part, without prior permission of the publishers.)

Congenital prosopagnosia (CP), a life-long impairment in face processing that occurs in the absence of any apparent brain damage, provides a unique model in which to explore the psychological and neural bases of normal face processing. The goal of this review is to offer a theoretical and conceptual framework that may account for the underlying cognitive and neural deficits in CP. This framework may also provide a novel perspective in which to reconcile some conflicting results that permits the expansion of the research in this field in new directions. The crux of this framework lies in linking the known behavioral and neural underpinnings of face processing and their impairments in CP to a model incorporating grid cell-like activity in the entorhinal cortex. Moreover, it stresses the involvement of active, spatial scanning of the environment with eye movements and implicates their critical role in face encoding and recognition. To begin with, we describe the main behavioral and neural characteristics of CP, and then lay down the building blocks of our proposed model, referring to the existing literature supporting this new framework. We then propose testable predictions and conclude with open questions for future research stemming from this model.

Objective: To contribute to the limited body of eye movement (EM) studies of children and family members with congenital prosopagnosia (CP), a task requiring a verbal response for the identification of personally familiar faces was used for the 1st time., Method: EMs were recorded in a father and his son (both diagnosed with CP) and controls (N = 2). In the identification tasks they watched personally familiar faces and distracters and responded by saying the names of the familiar faces or saying "I don't know." Two discrimination tasks were added to distinguish the specificity of the EM pattern for the recognition tasks. In all tasks, faces were presented 1 by 1 until the response onset; thus, the EM pattern was not saturated by overexposure to the stimulus. The 1st fixation position was examined to localize the 1st area of the face attended to. The spatial-temporal fixation pattern was examined to evaluate the attention devoted to specific regions., Results: Both family members were inaccurate and slower than controls in the identification but not the discrimination tasks. In all tasks, they made a number of fixations comparable to those of controls but showed longer fixation durations than controls did. In the identification tasks, they showed poor spatial-temporal distribution of fixations on the eyes and rare 1st fixations on the eyes., Conclusions: Consistent with the literature, both family members showed the typical reduced sampling of the eyes. Nevertheless, our protocol based on explicit verbal responses (which included EM only until response onset) showed that they did not increase the spatial sampling overall by making more fixations than controls did. Instead, they showed longer fixation durations across tasks; this was interpreted as a generalized problem with face processing in affording a more robust sampling of information. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

We report Developmental Landmark Agnosia (DLA) in a 6-year-old boy (L.G.) who was referred to us for congenital prosopagnosia (see Pizzamiglio et al., 2017 , in which both testing and rehabilitation of Congenital Prosopagnosia are reported). We investigated his performance using a neuropsychological battery and eye movement recordings. The assessment showed the presence of deficits in recognizing familiar places (along with Congenital Prosopagnosia), but not common objects. Eye movement recordings confirmed his problems in recognizing familiar landmarks and misrecognition of unfamiliar places. L.G. is the first evidence of a DLA, suggesting identification of taxonomy of navigational disorders in Developmental Topographical Disorientation is possible, as in the Acquired Topographical Disorientation.

Prosopagnosia is a disorder leading to difficulties in recognizing faces. However, recent evidence suggests that individuals with congenital prosopagnosia can achieve considerable accuracy when they have to recognize their own faces (self-face advantage). Yet, whether this advantage is face-specific or not is still unclear. Here, we aimed to investigate whether individuals with congenial prosopagnosia show a self-advantage also in recognizing other self body-parts and, if so, whether the advantage for the body parts differs from the one characterizing the self-face. Eight individuals with congenital prosopagnosia and 22 controls underwent a delayed matching task in which they were required to recognize faces, hands and feet belonging to the self or to others. Controls showed a similar self-advantage for all the stimuli tested; by contrast, individuals with congenital prosopagnosia showed a larger self-advantage with faces compared to hands and feet, mainly driven by their deficit with others' faces. In both groups the self-advantages for the different body parts were strongly and significantly correlated. Our data suggest that the self-face advantage showed by individuals with congenital prosopagnosia is not face-specific and that the same mechanism could be responsible for both the self-face and self body-part advantages.

Individuals with congenital prosopagnosia (CP) are impaired at identifying individual faces but do not appear to show impairments in extracting the average identity from a group of faces (known as ensemble coding). However, possible deficits in ensemble coding in a previous study (CPs n = 4) may have been masked because CPs relied on pictorial (image) cues rather than identity cues. Here we asked whether a larger sample of CPs (n = 11) would show intact ensemble coding of identity when availability of image cues was minimised. Participants viewed a "set" of four faces and then judged whether a subsequent individual test face, either an exemplar or a "set average", was in the preceding set. Ensemble coding occurred when matching (vs. mismatching) averages were mistakenly endorsed as set members. We assessed both image- and identity-based ensemble coding, by varying whether test faces were either the same or different images of the identities in the set. CPs showed significant ensemble coding in both tasks, indicating that their performance was independent of image cues. As a group, CPs' ensemble coding was weaker than controls in both tasks, consistent with evidence that perceptual processing of face identity is disrupted in CP. This effect was driven by CPs (n= 3) who, in addition to having impaired face memory, also performed particularly poorly on a measure of face perception (CFPT). Future research, using larger samples, should examine whether deficits in ensemble coding may be restricted to CPs who also have substantial face perception deficits., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Objective: Recent evidence showed that individuals with congenital face processing impairment (congenital prosopagnosia [CP]) are highly accurate when they have to recognize their own face (self-face advantage) in an implicit matching task, with a preference for the right-half of the self-face (right perceptual bias). Yet the perceptual strategies underlying this advantage are unclear. Here, we aimed to verify whether both the self-face advantage and the right perceptual bias emerge in an explicit task, and whether those effects are linked to a different scanning strategy between the self-face and unfamiliar faces., Method: Eye movements were recorded from 7 CPs and 13 controls, during a self/other discrimination task of stimuli depicting the self-face and another unfamiliar face, presented upright and inverted., Results: Individuals with CP and controls differed significantly in how they explored faces. In particular, compared with controls, CPs used a distinct eye movement sampling strategy for processing inverted faces, by deploying significantly more fixations toward the nose and mouth areas, which resulted in more efficient recognition. Moreover, the results confirmed the presence of a self-face advantage in both groups, but the eye movement analyses failed to reveal any differences in the exploration of the self-face compared with the unfamiliar face. Finally, no bias toward the right-half of the self-face was found., Conclusions: Our data suggest that the self-face advantage emerges both in implicit and explicit recognition tasks in CPs as much as in good recognizers, and it is not linked to any specific visual exploration strategies. (PsycINFO Database Record, ((c) 2018 APA, all rights reserved).)

A longstanding controversy concerns the functional organization of high-level vision, and the extent to which the recognition of different classes of visual stimuli engages a single system or multiple independent systems. We examine this in the context of congenital prosopagnosia (CP), a neurodevelopmental disorder in which individuals, without a history of brain damage, are impaired at face recognition. This paper reviews all CP cases from 1976 to 2016, and explores the evidence for the association or dissociation of face and object recognition. Of the 238 CP cases with data permitting a satisfactory evaluation, 80.3% evinced an association between impaired face and object recognition whereas 19.7% evinced a dissociation. We evaluate the strength of the evidence and correlate the face and object recognition behaviour. We consider the implications for theories of functional organization of the visual system, and offer suggestions for further adjudication of the relationship between face and object recognition.

The Benton Facial Recognition Test (BFRT) and Cambridge Face Memory Test (CFMT) are two of the most common tests used to assess face discrimination and recognition abilities and to identify individuals with prosopagnosia. However, recent studies highlighted that participant-stimulus match ethnicity, as much as gender, has to be taken into account in interpreting results from these tests. Here, in order to obtain more appropriate normative data for an Italian sample, the CFMT and BFRT were administered to a large cohort of young adults. We found that scores from the BFRT are not affected by participants' gender and are only slightly affected by participant-stimulus ethnicity match, whereas both these factors seem to influence the scores of the CFMT. Moreover, the inclusion of a sample of individuals with suspected face recognition impairment allowed us to show that the use of more appropriate normative data can increase the BFRT efficacy in identifying individuals with face discrimination impairments; by contrast, the efficacy of the CFMT in classifying individuals with a face recognition deficit was confirmed. Finally, our data show that the lack of inversion effect (the difference between the total score of the upright and inverted versions of the CFMT) could be used as further index to assess congenital prosopagnosia. Overall, our results confirm the importance of having norms derived from controls with a similar experience of faces as the "potential" prosopagnosic individuals when assessing face recognition abilities.

Using a novel, fMRI-based inter-subject functional correlation (ISFC) approach, which isolates stimulus-locked inter-regional correlation patterns, we compared the cortical topology of the neural circuit for face processing in participants with an impairment in face recognition, congenital prosopagnosia (CP), and matched controls. Whereas the anterior temporal lobe served as the major network hub for face processing in controls, this was not the case for the CPs. Instead, this group evinced hyper-connectivity in posterior regions of the visual cortex, mostly associated with the lateral occipital and the inferior temporal cortices. Moreover, the extent of this hyper-connectivity was correlated with the face recognition deficit. These results offer new insights into the perturbed cortical topology in CP, which may serve as the underlying neural basis of the behavioral deficits typical of this disorder. The approach adopted here has the potential to uncover altered topologies in other neurodevelopmental disorders, as well.

Objective: The lack of inversion effect for face recognition in congenital prosopagnosia (CP) is consistent with the hypothesis of a failure in holistic processing. However, although CPs' abnormal gaze behavior for upright faces has already been demonstrated, neither their scanning strategy for inverted faces, nor the possibility that their abnormal gaze behavior with upright faces is because of reasons other than the holistic deficit have been investigated yet., Method: We recorded the eye movements of a congenital prosopagnosic and a control group during the encoding of unknown faces, objects, and flowers. Two types of stimuli (faces and objects) were presented upright and inverted., Results: CPs explored upright and inverted faces in the same way (i.e., similar number of fixations of the same duration and similarly distributed), whereas controls increased the number of fixations and their duration during the presentation of inverted faces. By contrast, the 2 groups showed a similar inversion effect during the encoding of objects. Finally, CPs showed anomalous exploration of within-class objects (i.e., flowers) and impairment in subordinate-level object discrimination., Conclusions: Our results demonstrate that: (a) CPs use the same part-based strategy in encoding both upright and inverted faces, suggesting a possible interpretation of the lack of inversion effect in this population; (b) CPs' lack of inversion effect is face-specific and does not affect objects; (c) however, CPs' deficit seems not to be limited to faces, and to extend to individual-item recognition within a class. (PsycINFO Database Record, ((c) 2017 APA, all rights reserved).)

Here we report the assessment and treatment of a 6-year-old boy (L.G.) who was referred to us for congenital prosopagnosia (CP). We investigated his performance using a test battery and eye movement recordings pre- and post-training. L.G. showed deficits in recognising relatives and learning new faces, and misrecognition of unfamiliar people. Eye movement recordings showed that L.G. focused on the lower part of stimuli in naming tasks based on familiar or unfamiliar incomplete or complete faces. The training focused on improving his ability to explore internal features of faces, to discriminate specific facial features of familiar and unfamiliar faces, and to provide his family with strategies to use in the future. At the end of the training programme L.G. no longer failed to recognise close and distant relatives and classmates and did not falsely recognise unknown people.

It has been estimated that one out of 40 people in the general population suffer from congenital prosopagnosia (CP), a neurodevelopmental disorder characterized by difficulty identifying people by their faces. CP involves impairment in recognizing faces, although the perception of non-face stimuli may also be impaired. Given that social interaction depends not only on face processing, but also on the processing of bodies, it is of theoretical importance to ascertain whether CP is also characterized by body perception impairments. Here, we tested 11 CPs and 11 matched control participants on the Body Identity Recognition Task (BIRT), a forced-choice match-to-sample task, using stimuli that require processing of body-specific, not clothing-specific, features. Results indicated that the group of CPs were as accurate as controls on the BIRT, which is in line with the lack of body perception complaints by CPs. However, the CPs were slower than controls, and when accuracy and response times were combined into inverse efficiency scores (IESs), the group of CPs were impaired, suggesting that the CPs could be using more effortful cognitive mechanisms to be as accurate as controls. In conclusion, our findings demonstrate that CP may not generally be limited to face processing difficulties, but may also extend to body perception.

Face-recognition deficits, referred to with the term prosopagnosia (i.e., face blindness), may manifest during development in the absence of any brain injury (from here the term congenital prosopagnosia, CP). It has been estimated that approximately 2.5% of the population is affected by face-processing deficits not depending on brain lesions, and varying a lot in severity. The genetic bases of this disorder are not known. In this study we tested for genetic association between single-nucleotide polymorphisms (SNPs) in the oxytocin receptor gene (OXTR) and CP in a restricted cohort of Italian participants. We found evidence of an association between the common genetic variants rs53576 and rs2254298 OXTR SNPs and prosopagnosia. This association was also found when including an additional group of German individuals classified as prosopagnosic in the analysis. Our preliminary data provide initial support for the involvement of genetic variants of OXTR in a relevant cognitive impairment, whose genetic bases are still largely unexplored., (Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.)

There has been growing recognition of the contribution of medial and anterior temporal lobe structures to non-mnemonic functions, such as perception. To evaluate the nature of this contribution, we contrast the perceptual performance of three patient groups, all of whom have a perturbation of these temporal lobe structures. Specifically, we compare the profile of patients with focal hippocampal (HC) lesions, those with more extensive lesions to the medial temporal lobe (MTL) that include HC and perirhinal cortex (PrC), and those with congenital prosopagnosia (CP), whose deficit has been attributed to the disconnection of the anterior temporal lobe from more posterior structures. All participants completed a range of'oddity' tasks in which, on each trial, they determined which of four visual stimuli in a display was the'odd-one-out'. There were five stimulus categories including faces, scenes, objects (high and low ambiguity) and squares of different sizes. Comparisons were conducted separately for the HC, MTL and CP groups against their matched control groups and then the group data were compared to each other directly. The group profiles were easily differentiable. Whereas the HC group stood out for its difficulty in discriminating scenes and the CP group stood out for its disproportionate difficulty in discriminating faces with milder effects for scenes and high ambiguity objects, the MTL group evinced a more general discrimination deficit for faces, scenes and high ambiguity objects. The group differences highlight distinct profiles for each of the three groups and distinguish the signature perceptual impairments following more extended temporal lobe alterations. In the recent reconsideration of the role of the hippocampus and neocortex, Moscovitch and colleagues (Moscovitch et al., 2016) note that the medial temporal lobe structures play a role in non-mnemonic functions, such as perception, problem solving, decision-making and language. Here, we address this exact issue, specifically with respect to perception, and we dedicate this paper to Morris Moscovitch in recognition of his profound contribution to science, to his students and to his colleagues., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Congenital prosopagnosia (CP) is a severe face processing impairment that occurs in the absence of any obvious brain damage and has often been associated with a more general deficit in deriving holistic relations between facial features or even between non-face shape dimensions. Here we further characterized this deficit and examined a potential way to ameliorate it. To this end we manipulated phasic alertness using alerting cues previously shown to modulate attention and enhance global processing of visual stimuli in normal observers. Specifically, we first examined whether individuals with CP, similarly to controls, would show greater global processing when exposed to an alerting cue in the context of a non-facial task (Navon global/local task). We then explored the effect of an alerting cue on face processing (upright/inverted face discrimination). Confirming previous findings, in the absence of alerting cues, controls showed a typical global bias in the Navon task and an inversion effect indexing holistic processing in the upright/inverted task, while CP failed to show these effects. Critically, when alerting cues preceded the experimental trials, both groups showed enhanced global interference and a larger inversion effect. These results suggest that phasic alertness may modulate visual processing and consequently, affect global/holistic perception. Hence, these findings further reinforce the notion that global/holistic processing may serve as a possible mechanism underlying the face processing deficit in CP. Moreover, they imply a possible route for enhancing face processing in individuals with CP and thus shed new light on potential amelioration of this disorder., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

A major question in the domain of face perception is whether faces comprise a distinct visual category that is processed by specialized mechanisms, or whether face processing merely represents an extreme case of visual expertise. Here, we examined O.H, a 22 years old woman with congenital prosopagnosia (CP), who despite her severe deficits in face processing, acquired superior recognition skills for horses. To compare the nature of face and horse processing, we utilised the inversion manipulation, known to disproportionally affect faces compared to other objects, with both faces and horses. O.H's performance was compared to data obtained from two control groups that were either horse experts, or non-experts. As expected, both control groups exhibited the face inversion effect, while O.H did not show the effect, but importantly, none of the participants showed an inversion effect for horses. Finally, gaze behaviour toward upright and inverted faces and horses was indicative of visual skill but in a distinct fashion for each category. Particularly, both control groups showed different gaze patterns for upright compared to inverted faces, while O.H presented a similar gaze pattern for the two orientations that differed from that of the two control groups. In contrast, O.H and the horse experts exhibited a similar gaze pattern for upright and inverted horses, while non-experts showed different gaze patterns for different orientations. Taken together, these results suggest that visual expertise can be acquired independently from the mechanisms mediating face recognition., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The existence of a drift to base judgments more on the right half-part of facial stimuli, which falls in the observer's left visual field (left perceptual bias (LPB)), in normal individuals has been demonstrated. However, less is known about the existence of this phenomenon in people affected by face impairment from birth, namely congenital prosopagnosics. In the current study, we aimed to investigate the presence of the LPB under face impairment conditions using chimeric stimuli and the most familiar face of all: the self-face. For this purpose we tested 10 participants with congenital prosopagnosia and 21 healthy controls with a face matching task using facial stimuli, involving a spatial manipulation of the left and the right hemi-faces of self-photos and photos of others. Even though congenital prosopagnosics performance was significantly lower than that of controls, both groups showed a consistent self-face advantage. Moreover, congenital prosopagnosics showed optimal performance when the right side of their face was presented, that is, right perceptual bias, suggesting a differential strategy for self-recognition in those subjects. A possible explanation for this result is discussed.

Modularity of face processing is still a controversial issue. Congenital prosopagnosia (cPA), a selective and lifelong impairment in familiar face recognition without evidence of an acquired cerebral lesion, offers a unique opportunity to support this fundamental hypothesis. However, in spite of the pronounced behavioural impairment, identification of a functionally relevant neural alteration in congenital prosopagnosia by electrophysiogical methods has not been achieved so far. Here we show that persons with congenital prosopagnosia can be distinguished as a group from unimpaired persons using magnetoencephalography. Early face-selective MEG-responses in the range of 140 to 200ms (the M170) showed prolonged latency and decreased amplitude whereas responses to another category (houses) were indistinguishable between subjects with congenital prosopagnosia and unimpaired controls. Latency and amplitude of face-selective EEG responses (the N170) which were simultaneously recorded were statistically indistinguishable between subjects with cPA and healthy controls which resolves heterogeneous and partly conflicting results from existing studies. The complementary analysis of categorical differences (evoked activity to faces minus evoked activity to houses) revealed that the early part of the 170ms response to faces is altered in subjects with cPA. This finding can be adequately explained in a common framework of holistic and part-based face processing. Whereas a significant brain-behaviour correlation of face recognition performance and the size of the M170 amplitude is found in controls a corresponding correlation is not seen in subjects with cPA. This indicates functional relevance of the alteration found for the 170ms response to faces in cPA and pinpoints the impairment of face processing to early perceptual stages.

Background and Purpose: Congenital prosopagnosia is a life-long disorder of face perception. To study the neural backgrounds of congenital prosopagnosia we measured the blood oxygen level-dependent response of congenital prosopagnosic participants, using functional magnetic resonance imaging., Methods: We tested three persons of the family (father, daughter and son), having symptoms of congenital prosopagnosia, as well as healthy controls, using combined neuropsychological and functional magnetic resonance imaging methods. To reveal the neural correlates of the impairments, blood oxygen level-dependent responses within the occipito-temporal cortex were measured to faces and nonsense object images in a block-design experiment., Results: Neuropsychological tests demonstrated significant impairments of face perception/recognition in each subject. We found that the activity of the fusiform and occipital face areas as well as of the lateral occipital cortex was significantly reduced in congenital prosopagnosic participants when compared to controls. Analysis of the hemodynamic response function revealed a lower peak response, but also a significantly faster and stronger decay of the blood oxygen level-dependent response in the occipito-temporal areas in congenital prosopagnosic participants when compared to controls., Conclusion: Our results emphasize the dysfunction of the core face processing system, as well as the lateral occipital complex, in congenital prosopagnosia. Further, the functional impairment of these areas is signalled best by the altered hemodynamic response function, showing abnormally low initial peak and stronger and faster decay in the later parts of the blood oxygen level-dependent response.

It has recently been proposed that the face recognition deficits seen in neurodevelopmental disorders may reflect impaired short-term face memory (STFM). For example, introducing a brief delay between the presentation of target and test faces seems to disproportionately impair matching or recognition performance in individuals with Autism Spectrum Disorders. The present study sought to determine whether deficits of STFM contribute to impaired face recognition seen in Developmental Prosopagnosia. To determine whether developmental prosopagnosics exhibit impaired STFM, the present study used a six-alternative-forced-choice match-to-sample procedure. Memory demand was manipulated by employing a short or long delay between the presentation of the target face, and the six test faces. Crucially, the perceptual demands were identical in both conditions, thereby allowing the independent contribution of STFM to be assessed. Prosopagnosics showed clear evidence of a category-specific impairment for face-matching in both conditions; they were both slower and less accurate than matched controls. Crucially, however, the prosopagnosics showed no evidence of disproportionate face recognition impairment in the long-interval condition. While individuals with DP may have problems with the perceptual encoding of faces, it appears that their representations are stable over short durations. These results suggest that the face recognition difficulties seen in DP and autism may be qualitatively different, attributable to deficits of perceptual encoding and perceptual maintenance, respectively., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

We present the case of an individual with congenital prosopagnosia or "face blindness", a disorder where the ability to recognize faces is impaired. We studied the lip-reading ability and audiovisual perception of this subject using a DVD with four conditions (audiovisual congruent, auditory, visual, and audiovisual incongruent) and compared results with a normal patient cohort. The patient had no correct responses in the visual lip-reading task; whereas, he improved in the audiovisual congruent task. In the audiovisual incongruent task, the patient provided one response; thus, he was able to lip-read. (He was able to use lip-reading/to use labial informations) This patient perceived only global dynamic facial movements, not the fine ones. He had a sufficient complementary use of lip-reading in audiovisual tasks, but not visual ones. These data are consistent with abnormal development of the pathways used for visual speech perception and associated with second-order face processing disorders and normal development of the audiovisual network for speech perception.

Cognitive models propose that face recognition is accomplished through a series of discrete stages, including perceptual representation of facial structure, and encoding and retrieval of facial information. This implies that impaired face recognition can result from failures of face perception, face memory, or both. Studies of acquired prosopagnosia, autism spectrum disorders, and the development of normal face recognition support the idea that face perception and face memory are distinct processes, yet this distinction has received little attention in developmental prosopagnosia (DP). To address this issue, we tested the face perception and face memory of children and adults with DP. By definition, face memory is impaired in DP, so memory deficits were present in all participants. However, we found that all children, but only half of the adults had impaired face perception. Thus, results from adults indicate that face perception and face memory are dissociable, while the results from children provide no evidence for this division. Importantly, our findings raise the possibility that DP is qualitatively different in childhood versus adulthood. We discuss theoretical explanations for this developmental pattern and conclude that longitudinal studies are necessary to better understand the developmental trajectory of face perception and face memory deficits in DP., (Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.)

A woman in her early 40s with congenital prosopagnosia and attention deficit hyperactivity disorder observed for the first time sudden and extensive improvement of her face recognition abilities, mental imagery, and sense of navigation after galactose intake. This effect of galactose on prosopagnosia has never been reported before. Even if this effect is restricted to a subform of congenital prosopagnosia, galactose might improve the condition of other prosopagnosics. Congenital prosopagnosia, the inability to recognize other people by their face, has extensive negative impact on everyday life. It has a high prevalence of about 2.5%. Monosaccharides are known to have a positive impact on cognitive performance. Here, we report the case of a prosopagnosic woman for whom the daily intake of 5 g of galactose resulted in a remarkable improvement of her lifelong face blindness, along with improved sense of orientation and more vivid mental imagery. All these improvements vanished after discontinuing galactose intake. The self-reported effects of galactose were wide-ranging and remarkably strong but could not be reproduced for 16 other prosopagnosics tested. Indications about heterogeneity within prosopagnosia have been reported; this could explain the difficulty to find similar effects in other prosopagnosics. Detailed analyses of the effects of galactose in prosopagnosia might give more insight into the effects of galactose on human cognition in general. Galactose is cheap and easy to obtain, therefore, a systematic test of its positive effects on other cases of congenital prosopagnosia may be warranted.

Objective: Individuals with developmental prosopagnosia ('face blindness') have severe face recognition difficulties due to a failure to develop the necessary visual mechanisms for recognizing faces. These difficulties occur in the absence of brain damage and despite normal low-level vision and intellect. Adults with developmental prosopagnosia report serious personal and emotional consequences from their inability to recognize faces, but little is known about the psychosocial consequences in childhood. Given the importance of face recognition in daily life, and the potential for unique social consequences of impaired face recognition in childhood, we sought to evaluate the impact of developmental prosopagnosia on children and their families., Methods: We conducted semi-structured interviews with 8 children with developmental prosopagnosia and their parents. A battery of face recognition tests was used to confirm the face recognition impairment reported by the parents of each child. We used thematic analysis to develop common themes among the psychosocial experiences of the children and their parents., Results: Three themes were developed from the child reports: 1) awareness of their difficulties, 2) coping strategies, such as using non-facial cues to identify others, and 3) social implications, such as discomfort in, and avoidance of, social situations. These themes were paralleled by the parent reports and highlight the unique social and practical challenges associated with childhood developmental prosopagnosia., Conclusion: Our findings indicate a need for increased awareness and treatment of developmental prosopagnosia to help these children manage their face recognition difficulties and to promote their social and emotional wellbeing., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Congenital prosopagnosia is lifelong face-recognition impairment in the absence of evidence for structural brain damage. To study the neural correlates of congenital prosopagnosia, we measured the face-sensitive N170 component of the event-related potential in three members of the same family (father (56 y), son (25 y) and daughter (22 y)) and in age-matched neurotypical participants (young controls: n = 14; 24.5 y±2.1; old controls: n = 6; 57.3 y±5.4). To compare the face sensitivity of N170 in congenital prosopagnosic and neurotypical participants we measured the event-related potentials for faces and phase-scrambled random noise stimuli. In neurotypicals we found significantly larger N170 amplitude for faces compared to noise stimuli, reflecting normal early face processing. The congenital prosopagnosic participants, by contrast, showed reduced face sensitivity of the N170, and this was due to a larger than normal noise-elicited N170, rather than to a smaller face-elicited N170. Interestingly, single-trial analysis revealed that the lack of face sensitivity in congenital prosopagnosia is related to a larger oscillatory power and phase-locking in the theta frequency-band (4-7 Hz, 130-190 ms) as well as to a lower intertrial jitter of the response latency for the noise stimuli. Altogether, these results suggest that congenital prosopagnosia is due to the deficit of early, structural encoding steps of face perception in filtering between face and non-face stimuli.

There is growing consensus that accurate and efficient face recognition is mediated by a neural circuit composed of a posterior "core" and an anterior "extended" set of regions. Here, we characterize the distributed face network in human individuals with congenital prosopagnosia (CP)-a lifelong impairment in face processing-relative to that of matched controls. Using functional magnetic resonance imaging, we first uncover largely normal activation patterns in the posterior core face patches in CP. We also document normal activity of the amygdala (emotion processing) as well as normal or even enhanced functional connectivity between the amygdala and the core regions. Critically, in the same individuals, activation of the anterior temporal cortex (identity processing) is reduced and connectivity between this region and the posterior core regions is disrupted. The dissociation between the neural profiles of the anterior temporal lobe and amygdala was evident both during a task-related face scan and during a resting state scan, in the absence of visual stimulation. Taken together, these findings elucidate selective disruptions in neural circuitry in CP and offer an explanation for the known differential difficulty in identity versus emotional expression recognition in many individuals with CP.

The goal of the current paper is to review recent findings concerning the neural basis of congenital prosopagnosia (CP), a lifelong impairment in face processing that occurs in the absence of explicit brain damage. As such, CP offers a unique model for exploring the psychological and neural bases of normal face processing. We start by providing background about face perception and representation, and then review behavioral evidence gleaned from individuals with CP. We then review recent functional and structural neural investigations which offer a comprehensive account of the mechanisms underlying CP and support a characterization of this impairment as a disconnection syndrome rather than as a syndrome related to focal brain malfunction. We end the paper by offering a general framework for CP which, we believe, best integrates the behavioral and neural findings, and offers a platform for generating hypotheses for future studies. There remain many open issues in our understanding of CP and, to address these unanswered questions, we lay out several future research directions and testable hypotheses for further investigation.

Prosopagnosia has largely been regarded as an untreatable disorder. However, recent case studies using cognitive training have shown that it is possible to enhance face recognition abilities in individuals with developmental prosopagnosia. Our goal was to determine if this approach could be effective in a larger population of developmental prosopagnosics. We trained 24 developmental prosopagnosics using a 3-week online face-training program targeting holistic face processing. Twelve subjects with developmental prosopagnosia were assessed before and after training, and the other 12 were assessed before and after a waiting period, they then performed the training, and were then assessed again. The assessments included measures of front-view face discrimination, face discrimination with view-point changes, measures of holistic face processing, and a 5-day diary to quantify potential real-world improvements. Compared with the waiting period, developmental prosopagnosics showed moderate but significant overall training-related improvements on measures of front-view face discrimination. Those who reached the more difficult levels of training ('better' trainees) showed the strongest improvements in front-view face discrimination and showed significantly increased holistic face processing to the point of being similar to that of unimpaired control subjects. Despite challenges in characterizing developmental prosopagnosics' everyday face recognition and potential biases in self-report, results also showed modest but consistent self-reported diary improvements. In summary, we demonstrate that by using cognitive training that targets holistic processing, it is possible to enhance face perception across a group of developmental prosopagnosics and further suggest that those who improved the most on the training task received the greatest benefits., (© The Author (2014). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Congenital prosopagnosia (CP) describes a severe face processing impairment despite intact early vision and in the absence of overt brain damage. CP is assumed to be present from birth and often transmitted within families. Previous studies reported conflicting findings regarding associated deficits in nonface visuoperceptual tasks. However, diagnostic criteria for CP significantly differed between studies, impeding conclusions on the heterogeneity of the impairment. Following current suggestions for clinical diagnoses of CP, we administered standardized tests for face processing, a self-report questionnaire and general visual processing tests to an extended family (N=28), in which many members reported difficulties with face recognition. This allowed us to assess the degree of heterogeneity of the deficit within a large sample of suspected CPs of similar genetic and environmental background. (a) We found evidence for a severe face processing deficit but intact nonface visuoperceptual skills in three family members - a father and his two sons - who fulfilled conservative criteria for a CP diagnosis on standardized tests and a self-report questionnaire, thus corroborating findings of familial transmissions of CP. (b) Face processing performance of the remaining family members was also significantly below the mean of the general population, suggesting that face processing impairments are transmitted as a continuous trait rather than in a dichotomous all-or-nothing fashion. (c) Self-rating scores of face recognition showed acceptable correlations with standardized tests, suggesting this method as a viable screening procedure for CP diagnoses. (d) Finally, some family members revealed severe impairments in general visual processing and nonface visual memory tasks either in conjunction with face perception deficits or as an isolated impairment. This finding may indicate an elevated risk for more general visuoperceptual deficits in families with prosopagnosic members., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Congenital prosopagnosia (CP) refers to lifelong and severe impairment of face processing, which is apparent from birth, despite intact visual and intellectual abilities. Usually, individuals with CP do not exhibit brain lesions or neurological disorders that account for their specific impairment. An epidemiological survey revealed that the prevalence rate of CP was approximately 2.5% in a young Caucasian population. CP frequently runs in families, suggesting a genetic component in this disturbance. Detailed neuropsychological investigations demonstrated that individuals with CP show reduced performance in face tasks including famous face recognition, face matching, and encoding/retrieval of novel faces. In contrast, they can judge facial expression and eye gaze almost as well as healthy controls. These results suggest an impairment of holistic processing of faces in individuals with CP. Neurophysiological investigation using ERP showed that individuals with CP, as a group, had reduced voltage of the N170 component, which is a hallmark of face processing in the temporal lobe. However, there were large variations in the results of N170 among individuals with CP. Structural MRI showed that the impairments could be due to reduced volume of grey matter and microstructure of white matter in a part of the temporal lobe. Studies using fMRI and face tasks revealed mixed results with regard to face-selective activation in the fusiform gyrus. These findings indicate the heterogeneity of CP, and further investigation is needed to clarify neurodevelopmental substrates of face processing. Results from normative data obtained using the Japanese version of a questionnaire for screening of hereditary prosopagnosia is presented.

The term covert recognition refers to recognition without awareness. In the context of face recognition, it refers to the fact that some individuals show behavioural, electrophysiological or autonomic indices of recognition in the absence of overt, conscious recognition. Originally described in cases of people that have lost their ability to overtly recognize faces (acquired prosopagnosia, AP), covert face recognition has more recently also been described in cases of congenital prosopagnosia (CP), who never develop typical overt face recognition skills. The presence of covert processing in a developmental disorder such as CP is a particularly intriguing phenomenon, and its investigation is relevant for a variety of reasons. From a theoretical point of view, it is useful to help shed light on the cognitive and neural underpinnings of face recognition deficits. From a clinical point of view, it has the potential to aid the design of rehabilitation protocols aimed at improving face recognition skills in this population. In the current review we selectively summarize the recent literature on covert face recognition in CP, highlight its main findings, and provide a theoretical interpretation for them.

Congenital prosopagnosia is a condition that, present from an early age, makes it difficult for an individual to recognise someone from his or her face. Typically, research into prosopagnosia has employed static images that do not contain the extra information we can obtain from moving faces and, as a result, very little is known about the role of facial motion for identity processing in prosopagnosia. Two experiments comparing the performance of four congenital prosopagnosics with that of age matched and younger controls on their ability to learn and recognise (Experiment 1) and match (Experiment 2) novel faces are reported. It was found that younger controls' recognition memory performance increased with dynamic presentation, however only one of the four prosopagnosics showed any improvement. Motion aided matching performance of age matched controls and all prosopagnosics. In addition, the face inversion effect, an effect that tends to be reduced in prosopagnosia, emerged when prosopagnosics matched moving faces. The results suggest that facial motion can be used as a cue to identity, but that this may be a complex and difficult cue to retain. As prosopagnosics performance improved with the dynamic presentation of faces it would appear that prosopagnosics can use motion as a cue to recognition, and the different patterns for the face inversion effect that occurred in the prosopagnosics for static and dynamic faces suggests that the mechanisms used for dynamic facial motion recognition are dissociable from static mechanisms., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Congenital prosopagnosia (CP), a lifelong impairment in face processing in the absence of brain damage, is often ascribed to impairment in holistic processing. It is still debated whether such difficulties are restricted to faces or whether they can also be observed for nonfacial stimuli. Here, we investigate this issue by examining CP individuals and their controls on two variations of the Garner speeded classification task tailored to assess holistic processing of nonfacial stimuli. In Experiment 1, participants were asked to judge the width of visually presented rectangles while ignoring their irrelevant height, or to judge changes in width while height remained constant. Critically, while controls exhibited the expected Garner interference, no such interference was observed for the CPs, indicating impaired holistic processing of integral, nonfacial shape dimensions. Experiment 2, utilized the same Garner paradigm, but here participants were asked to judge integral dimensions that are unrelated to shape (colour). Importantly, both CPs and controls exhibited the same level of Garner interference, indicating intact integral processing of colour dimensions. This dissociation between the performance on the two Garner tasks indicates that CPs do not exhibit a general local processing bias or impaired integration of any perceptual dimensions, but rather a deficit that is restricted to tasks requiring holistic integral perception of shape dimensions. Taken together, these results provide evidence for the existence of a general impairment in holistic shape perception in CP, which may be related to the mechanisms underlying this disorder.

Introduction: Even though people with congenital prosopagnosia (CP) never develop a normal ability to "overtly" recognize faces, some individuals show indices of "covert" (or implicit) face recognition. The aim of this study was to demonstrate covert face recognition in CP when participants could not overtly recognize the faces., Methods: Eleven people with CP completed three tasks assessing their overt face recognition ability, and three tasks assessing their "covert" face recognition: a Forced choice familiarity task, a Forced choice cued task, and a Priming task., Results: Evidence of covert recognition was observed with the Forced choice familiarity task, but not the Priming task. In addition, we propose that the Forced choice cued task does not measure covert processing as such, but instead "provoked-overt" recognition., Conclusions: Our study clearly shows that people with CP demonstrate covert recognition for faces that they cannot overtly recognize, and that behavioural tasks vary in their sensitivity to detect covert recognition in CP., (Copyright © 2011 Elsevier Srl. All rights reserved.)

Because holistic processing is a hallmark of normal face recognition, we ask whether such processing is reduced in developmental prosopagnosia (DP), and, if so, what the sources are of this deficit. Existing literature provides a mixed picture, with face inversion effects showing consistent holistic processing deficits but unable to locate their source and with some composite face studies showing reduced holistic processing and some not. We addressed this issue more thoroughly with a very large sample of DPs (N = 38) performing the part-whole task, a well-accepted measure of holistic processing that allows for the separate evaluation of individual face parts. Contrary to an expected overall reduction in holistic processing, we found an intact holistic advantage for the mouth and a complete absence of a holistic advantage for the eye region. Less severely impaired prosopagnosics showed significantly more holistic processing of the mouth, suggesting that holistic processing can aid them in recognizing faces.

People with developmental prosopagnosia (DP) show severe face-recognition deficits that typically emerge during childhood without history of neurological damage. We review findings from recent event-related brain potential (ERP) studies of face perception and face recognition in DP. The generic face-sensitivity of the N170 component is present in most DPs, suggesting rapid category-selective streaming of facial information. In contrast, DPs show atypical N170 face inversion effects, indicative of impaired structural encoding, specifically for upright faces. In line with neurodevelopmental accounts of DP, these effects are similar to those observed for other developmental disorders, as well as for younger children and older adults. Identity-sensitive ERP components (N250, P600f) triggered during successful face recognition are similar for DPs and control participants, indicating that the same mechanisms are active in both groups. The presence of covert face-recognition effects for the N250 component suggests that visual face memory and semantic memory can become disconnected in some individuals with DP. The implications of these results for neuropsychological and neurodevelopmental perspectives on DP are discussed.

This study addresses two central and controversial issues in developmental prosopagnosia (DP), configuration- versus feature-based face processing and the influence of affective information from either facial or bodily expressions on face recognition. A sample of 10 DPs and 10 controls were tested with a previously developed face and object recognition and memory battery (Facial Expressive Action Stimulus Test, FEAST), a task measuring the influence of emotional faces and bodies on face identity matching (Face-Body Compound task), and an emotionally expressive face memory task (Emotional Face Memory task, FaMe-E). We show that DPs were impaired in upright, but not inverted, face matching but they performed at the level of controls on part-to-whole matching. Second, DPs showed impaired memory for both neutral and emotional faces and scored within the normal range on the Face-Body Compound task. Third, configural perception but not feature-based processing was significantly associated with memory performance. Taken together the results indicate that DPs have a deficit in configural processing at the perception stage that may underlie the memory impairment.

Developmental prosopagnosia is characterized by a severe deficit in face-identity recognition. Most developmental prosopagnosics do not report deficits of facial age or gender perception. We developed tasks for evaluating facial age and gender processing and used them in the largest group of developmental prosopagnosics (N = 18) tested on facial age and gender perception. Care was taken to ensure that the tests were sufficiently sensitive to subtle deficits and required holistic processing as assessed by strong inversion effects in control subjects. Despite severe facial identity deficits, developmental prosopagnosics largely performed these discriminations comparably to controls. The common descriptor "faceblind" implied by the term prosopagnosia is inaccurate as certain kinds of nonidentity facial information, which we call physiognomic features, are processed well by both prosopagnosics and age-matched controls alike. Normal facial age and gender perception in developmental prosopagnosics is consistent with parallel processing models in the cognitive architecture of face processing.

Developmental prosopagnosia (DP) is defined by severe face recognition problems resulting from a failure to develop the necessary visual mechanisms for processing faces. While there is a growing literature on DP in adults, little has been done to study this disorder in children. The profound impact of abnormal face perception on social functioning and the general lack of awareness of childhood DP can result in severe social and psychological consequences for children. This review discusses possible aetiologies of DP and summarizes the few cases of childhood DP that have been reported. It also outlines key objectives for the growth of this emerging research area and special considerations for studying DP in children. With clear goals and concerted efforts, the study of DP in childhood will be an exciting avenue for enhancing our understanding of normal and abnormal face perception for all age groups.

The deficit in face recognition in individuals with prosopagnosia has often been attributed to an underlying impairment in holistic processing. Exactly what constitutes holistic processing has remained controversial, however. Here, we compare how configural information and featural information interact during face processing in a group of individuals with congenital prosopagnosia (CP) and matched controls. We adopted Amishav and Kimchi's version of Garner's speeded classification task, in which observers classify upright faces based on configural (intereyes and nose-mouth spacing) or featural (shape of eyes, nose, and mouth) information while the other dimension remains constant or varied randomly. We replicated the finding that normal observers evince symmetric Garner interference--failure to selectively attend to features without being influenced by irrelevant variation in configuration, and vice versa--indicating that featural and configural information are integral in normal face processing. In contrast, the CPs showed no Garner interference: They were able to attend to configural information without interference from irrelevant variation in featural information, and they were able to attend to featural information without interference from irrelevant variation in configural information. The absence of Garner interference in CP provides strong evidence that featural information and configural information are perceptually separable in CP's face processing. These findings indicate that CPs do not perceive faces holistically; rather, they process featural and configural information independently.

The author gives an anecdotal account of his life with developmental prosopagnosia (DP). He was not formally diagnosed until the age of 53 and has evolved a complicated strategy for recognizing people based on non-facial physical features and context. He describes his experiences through infancy, school, university life and courtship, work and family life. He believes that he has lived a full and successful life despite DP but that some aspects of his social and work life were impaired by face-blindness. In his experience people react positively and helpfully if the consequences of DP are explained to them, and this improves social interactions and communications.

People with congenital prosopagnosia (CP) report difficulty recognising faces in everyday life and perform poorly on face recognition tests. Here, we investigate whether impaired adaptive face space coding might contribute to poor face recognition in CP. To pinpoint how adaptation may affect face processing, a group of CPs and matched controls completed two complementary face adaptation tasks: the figural aftereffect, which reflects adaptation to general distortions of shape, and the identity aftereffect, which directly taps the mechanisms involved in the discrimination of different face identities. CPs displayed a typical figural aftereffect, consistent with evidence that they are able to process some shape-based information from faces, e.g., cues to discriminate sex. CPs also demonstrated a significant identity aftereffect. However, unlike controls, CPs impression of the identity of the neutral average face was not significantly shifted by adaptation, suggesting that adaptive coding of identity is abnormal in CP. In sum, CPs show reduced aftereffects but only when the task directly taps the use of face norms used to code individual identity. This finding of a reduced face identity aftereffect in individuals with severe face recognition problems is consistent with suggestions that adaptive coding may have a functional role in face recognition., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Congenital prosopagnosia is a selective deficit in face identification that is present from birth. Previously, behavioral deficits in face recognition and differences in the neuroanatomical structure and functional activation of face processing areas have been documented mostly in separate studies. Here, we propose a neural network model of congenital prosopagnosia which relates behavioral and neuropsychological studies of prosopagnosia to theoretical models of information processing. In this study we trained a neural network with two different algorithms to represent face images. First, we introduced a predisposition towards a decreased network connectivity implemented as a temporal independent component analysis (ICA). This predisposition induced a featural representation of faces in terms of isolated face parts. Second, we trained the network for optimal information encoding using spatial ICA, which led to holistic representations of faces. The network model was then tested empirically in an experiment with ten prosopagnosic and twenty age-matched controls. Participants had to discriminate between faces that were changed either according to the prosopagnosic model of featural representation or to the control model of holistic representation. Compared to controls prosopagnosic participants were impaired only in discriminating holistic changes of faces but showed no impairment in detecting featural changes. In summary, the proposed model presents an empirically testable account of congenital prosopagnosia that links the critical features--a lack of holistic processing at the computational level and a sparse structural connectivity at the implementation level. More generally, our results point to structural differences in the network connectivity as the cause of the face processing deficit in congenital prosopagnosia., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

It has long been argued that face processing requires disproportionate reliance on holistic or configural processing, relative to that required for non-face object recognition, and that a disruption of such holistic processing may be causally implicated in prosopagnosia. Previously, we demonstrated that individuals with congenital prosopagnosia (CP) did not show the normal face inversion effect (better performance for upright compared to inverted faces) and evinced a local (rather than the normal global) bias in a compound letter global/local (GL) task, supporting the claim of disrupted holistic processing in prosopagnosia. Here, we investigate further the nature of holistic processing impairments in CP, first by confirming, in a large sample of CP individuals, the absence of the normal face inversion effect and the presence of the local bias on the GL task, and, second, by employing the composite face paradigm, often regarded as the gold standard for measuring holistic face processing. In this last task, we show that, in contrast with controls, the CP group perform equivalently with aligned and misaligned faces and was impervious to (the normal) interference from the task-irrelevant bottom part of faces. Interestingly, the extent of the local bias evident in the composite task is correlated with the abnormality of performance on diagnostic face processing tasks. Furthermore, there is a significant correlation between the magnitude of the local bias in the GL and performance on the composite task. These results provide further evidence for impaired holistic processing in CP and, moreover, corroborate the critical role of this type of processing for intact face recognition., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Background: Congenital prosopagnosia (CP) describes an impairment in face processing that is presumably present from birth. The neuronal correlates of this dysfunction are still under debate. In the current paper, we investigate high-frequent oscillatory activity in response to faces in persons with CP. Such neuronal activity is thought to reflect higher-level representations for faces., Methodology: Source localization of induced Gamma-Band Responses (iGBR) measured by magnetoencephalography (MEG) was used to establish the origin of oscillatory activity in response to famous and unknown faces which were presented in upright and inverted orientation. Persons suffering from congenital prosopagnosia (CP) were compared to matched controls., Principal Findings: Corroborating earlier research, both groups revealed amplified iGBR in response to upright compared to inverted faces predominately in a time interval between 170 and 330 ms and in a frequency range from 50-100 Hz. Oscillatory activity upon known faces was smaller in comparison to unknown faces, suggesting a "sharpening" effect reflecting more efficient processing for familiar stimuli. These effects were seen in a wide cortical network encompassing temporal and parietal areas involved in the disambiguation of homogenous stimuli such as faces, and in the retrieval of semantic information. Importantly, participants suffering from CP displayed a strongly reduced iGBR in the left fusiform area compared to control participants., Conclusions: In sum, these data stress the crucial role of oscillatory activity for face representation and demonstrate the involvement of a distributed occipito-temporo-parietal network in generating iGBR. This study also provides the first evidence that persons suffering from an agnosia actually display reduced gamma band activity. Finally, the results argue strongly against the view that oscillatory activity is a mere epiphenomenon brought fourth by rapid eye-movements (micro saccades).