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Gaze-contingency is a method traditionally used to investigate the perceptual span in reading by selectively revealing/masking a portion of the visual field in real time. Introducing this approach in face perception research showed that the performance pattern of a brain-damaged patient with acquired prosopagnosia (PS) in a face matching task was reversed, as compared to normal observers: the patient showed almost no further decrease of performance when only one facial part (eye, mouth, nose, etc.) was available at a time (foveal window condition, forcing part-based analysis), but a very large impairment when the fixated part was selectively masked (mask condition, promoting holistic perception) (Van Belle, De Graef, Verfaillie, Busigny, & Rossion, 2010a; Van Belle, De Graef, Verfaillie, Rossion, & Lefèvre, 2010b). Here we tested the same manipulation in a recently reported case of pure prosopagnosia (GG) with unilateral right hemisphere damage (Busigny, Joubert, Felician, Ceccaldi, & Rossion, 2010). Contrary to normal observers, GG was also significantly more impaired with a mask than with a window, demonstrating impairment with holistic face perception. Together with our previous study, these observations support a generalized account of acquired prosopagnosia as a critical impairment of holistic (individual) face perception, implying that this function is a key element of normal human face recognition. Furthermore, the similar behavioral pattern of the two patients despite different lesion localizations supports a distributed network view of the neural face processing structures, suggesting that the key function of human face processing, namely holistic perception of individual faces, requires the activity of several brain areas of the right hemisphere and their mutual connectivity., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Background: Pure alexia and prosopagnosia are two separate and uncommon disorders of visual recognition in neuro-ophthalmology. We report an extremely rare case of pure alexia coincident with prosopagnosia secondary to occipital arteriovenous malformation. The manifestations of these two visual recognition disorders are also described., Methods: A 35-year-old, left-handed women had suffered from severe blurred vision when recognizing her family's faces and was unable to read or associate separate parts of a word into a whole word. Her visual field revealed slight right homonymous hemianopia. Computed tomography scans and magnetic resonance images were arranged and vertebral angiography confirmed the diagnosis of left occipital arteriovenous malformation., Results: Gamma-knife stereoscopic radiotherapy was performed. Two months after the treatment, the ability to recognize faces and read improved and the visual field recovered., Conclusions: Ophthalmologists should keep in mind that usual complaints of "blurred vision" might correlate with unusual visual recognition disorders. Pure alexia and prosopagnosia have not been reported to occur together and the left-handed- dominance in our case leads to this scarce concurrence.

A 66-year-old, right-handed male, was admitted to our hospital with difficulty in recognizing faces and colors. He had suffered a stroke in the right occipital region three years earlier that had induced left homonymous hemianopsia, but not prosopagnosia. A neurological examination revealed prosopagnosia, color agnosia, constructional apraxia, and topographical disorientation, but not either hemineglect or dressing apraxia. The patient was unable to distinguish faces of familiar persons such as his family and friends, as well as those of unfamiliar persons such as doctors and nurses. Brain MRI demonstrated an old infarction in the right medial occipital lobe and a new hemorrhagic infarction in the left medial occipital lobe, including the fusiform and lingual gyrus. It is unclear whether a purely right medial occipital lesion can be responsible for prosopagnosia, or whether bilateral medial occipital lesions are necessary for this occurrence. The current case indicated that bilateral medial occipital lesions play an important role in inducing porsopagnosia.

Introduction: Several studies have assessed the impact of surgery on both anterograde and remote memory in patients with temporal lobe epilepsy (TLE). The majority of results have shown an extensive memory deficit in patients after temporal resection (TL). However, few protocols have used a prospective longitudinal design. Moreover, the postoperative delays were variable from one study to the next, instead of regular monitoring to identify the potential effect of time elapsed after surgery on memory performance. In addition, some studies have not used strict inclusion criteria to establish homogeneous patient groups. Finally, the impact of surgery on memory has been often assessed by comparing memory skills between epileptic patients and healthy controls. Our aim was to examine the impact of TL on memory in patients with TLE, recruited according to clear-cut clinical criteria. Moreover, we focused on memory performance progression per se in epileptic patients pre- and postoperatively, rather than on memory performance analysis expressed as "deficient" or "normal"., Methods: We assessed 30 patients with unilateral TLE (17 right TLE and 13 left TLE) on four anterograde memory tests and six remote memory tasks. Patients completed all tests preoperatively, and 5 and 12 months after TL., Results: Five months after surgery, performance was equivalent to the preoperative scores for both groups in anterograde memory tasks and remote memory tests. One year after TL, patients with right TLE showed enhanced performance in the verbal anterograde memory tests and in retrieving recent autobiographical memories. Results for left TL showed improved scores only in a recognition memory test of faces., Conclusions: In the present study, surgical patients were "double winners" gaining seizure freedom and potential of memory stability or recovery. The gain was observed only 12 months after surgery and following temporal resection lateralisation. Our data showed postoperative memory improvement in patients with temporal lobe epilepsy presenting with specific clinical characteristics., (Copyright © 2010 Elsevier Masson SAS. All rights reserved.)

Purpose of Review: Both monkey and human neuroimaging studies show that visual processing beyond the striate cortex involves a highly complex network of regions with modular functions. Lesions within this network lead to specific clinical syndromes. In this review we discuss studies on blindsight, which is the ability of remaining regions to support vision in the absence of striate cortex or visual awareness, recent work on 'ventral stream' syndromes such as object agnosia, alexia, prosopagnosia, and topographagnosia, which follow damage to medial occipitotemporal structures, and simultanagnosia, the classic 'dorsal stream' deficit related to bilateral occipitoparietal lesions., Recent Findings: We highlight work on the anatomic basis of blindsight, the recent description of the new disorder developmental topographic disorientation, and studies contrasting global and local perception in simultanagnosia., Summary: These studies advance our understanding of the mechanisms of complex visual processing and provide an important neuropsychological complement to our expanding knowledge about vision from functional neuroimaging.

Objective: We used event-related potentials (ERPs) to examine the recognition of familiar faces and scenes in patients with very mild Alzheimer disease (VMAD)., Methods: Two types of stimuli, FACEs and SCENEs, and two versions of each type, FAMILIAR and NOVEL, were presented. Three ERPs were compared between VMAD and normal control (NC): (1) P100 to examine basic visual processing, (2) N170 structural encoding, and (3) N250r familiarity., Results: A prominent N170 was elicited by FACEs in P8 and the largest N170 by SCENEs in P3 and P4. Participants had more errors when judging pictures of SCENEs as familiar or not than that of FACEs. In P3 and P4, NC produced larger N170 than VMAD. From N250r in F3, the familiarity effect was absent in VMAD when familiar scenes were provided. This deficit was not seen in processing familiar faces., Conclusions: This study shows that different neural regions are responsible for the early visual processing in the structural encoding of scenes and faces. The pattern of P100 and that of N170 suggest that VMAD patients maintain basic visual processing and structural encoding abilities. A conflict between behavioral and physiological responses may play a role in VMAD patients' risk of getting lost in familiar environments., Significance: Scene recognition is impaired earlier than face recognition in the course of Alzheimer disease., (2010 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.)

Face recognition is an important ability of the human brain, yet its underlying mechanisms are still poorly understood. Two opposite views have been proposed to account for human face recognition expertise: the ability to extract the most diagnostic local information, feature-by feature (analytical view), or the ability to process all features at once over the whole face (holistic view). To help clarifying this debate, we used an original gaze-contingent stimulus presentation method to compare normal observers and a brain-damaged patient specifically impaired at face recognition (prosopagnosia). When a single central facial feature was revealed at a time through a gaze-contingent window, normal observers' performance at an individual face matching task decreased to the patient level. However, when only the central feature was masked, forcing normal observers to rely on the whole face but the fixated feature, their performance was almost not affected. In contrast, the prosopagnosic patient's performance decreased dramatically in this latter condition. These results were independent of the absolute size of the face and window/mask. This dissociation indicates that expertise in face recognition does not rest on the ability to analyze diagnostic local detailed features sequentially but rather on the ability to see the individual features of a face all at once, a function that is critically impaired in acquired prosopagnosia., (Copyright (c) 2010 Elsevier Ltd. All rights reserved.)

We tested rapid-categorization in a patient who was impaired in face and object recognition. Photographs of natural scenes were displayed for 100 ms. Participants had to press a key when they saw an animal among various objects as distractors or human faces among animal faces as distractors. Though the patient was impaired at figure/ground segregation, recognized very few objects and faces, she categorized animals and faces with a performance ranging between 70 and 86% correct. Displaying pictures in isolation did not improve performance. The results suggest that rapid categorization can be accomplished on the basis of coarse information without overt recognition.

Acquired prosopagnosia (AP) is characterized by impaired recognition of individual faces following brain damage. The nature of the functional impairment(s) underlying AP remains debated. Recent studies have demonstrated deficient processing of diagnostic information in the region of the eyes (Caldara et al., 2005); other studies suggest that patients fail to judge relative distances between facial features (Barton et al., 2002). We hypothesized that these apparently different observations are related to a common cause. More precisely, we suggest that AP arises due to an impairment of a process that reduces uncertainty about the nature/location of the diagnostic cues for face individualization: the ability to perceive multiple elements of a face as a single global representation (holistic processing). Being impaired at processing individual faces holistically, prosopagnosic patients would tend to perform relatively worse for processing facial areas containing multiple elements (i.e., the eyes), and for elements that are widely spaced apart. Here we tested PS, a single case of AP, at matching unfamiliar faces differing either with respect to local features or inter-feature distances, over the upper and lower areas of the face. A pilot study and Experiment 1 confirmed that PS was extremely poor at using information encompassing the eyes, but was also deficient at perceiving relative distances between features. When uncertainty about the location and nature of the diagnostic cue was removed in Experiment 2, PS' performance remained below normal range, but she improved substantially. Most interestingly, her pattern of performance across the different conditions appeared qualitatively identical to that of normal controls. In line with previous observations of PS and other cases of prosopagnosia, our findings indicate that the reduced reliance on the area of the eyes and on relative distances between features in AP may have a common underlying cause-the disruption of holistic processing of the individual face., (Copyright (c) 2009 Elsevier Srl. All rights reserved.)

Prosopagnosia is an impairment at individualizing faces that classically follows brain damage. Several studies have reported observations supporting an impairment of holistic/configural face processing in acquired prosopagnosia. However, this issue may require more compelling evidence as the cases reported were generally patients suffering from integrative visual agnosia, and the sensitivity of the paradigms used to measure holistic/configural face processing in normal individuals remains unclear. Here we tested a well-characterized case of acquired prosopagnosia (PS) with no object recognition impairment, in five behavioral experiments (whole/part and composite face paradigms with unfamiliar faces). In all experiments, for normal observers we found that processing of a given facial feature was affected by the location and identity of the other features in a whole face configuration. In contrast, the patient's results over these experiments indicate that she encodes local facial information independently of the other features embedded in the whole facial context. These observations and a survey of the literature indicate that abnormal holistic processing of the individual face may be a characteristic hallmark of prosopagnosia following brain damage, perhaps with various degrees of severity., (Copyright (c) 2009 Elsevier Ltd. All rights reserved.)

There are few detailed studies of impaired voice recognition, or phonagnosia. Here we describe two patients with progressive phonagnosia in the context of frontotemporal lobar degeneration. Patient QR presented with behavioural decline and increasing difficulty recognising familiar voices, while patient KL presented with progressive prosopagnosia. In a series of neuropsychological experiments we assessed the ability of QR and KL to recognise and judge the familiarity of voices, faces and proper names, to recognise vocal emotions, to perceive and discriminate voices, and to recognise environmental sounds and musical instruments. The patients were assessed in relation to a group of healthy age-matched control subjects. QR exhibited severe impairments of voice identification and familiarity judgments with relatively preserved recognition of difficulty-matched faces and environmental sounds; recognition of musical instruments was impaired, though better than recognition of voices. In contrast, patient KL exhibited severe impairments of both voice and face recognition, with relatively preserved recognition of musical instruments and environmental sounds. Both patients demonstrated preserved ability to analyse perceptual properties of voices and to recognise vocal emotions. The voice processing deficit in both patients could be characterised as associative phonagnosia: in the case of QR, this was relatively selective for voices, while in the case of KL, there was evidence for a multimodal impairment of person knowledge. The findings have implications for current cognitive models of voice recognition., (Copyright (c) 2009 Elsevier Ltd. All rights reserved.)

The aim of this study consisted of using neuropsychological data obtained in two patients (VL and StG) showing a selective atrophy of the anterior parts of the right (VL) and left (StG) temporal lobes to check current cognitive models of familiar people identification. According to these models, information coming from modality-specific "face", "voice" and "name" recognition units converge into "Person Identity Nodes" (PINs) where familiarity feelings are generated and which provide a modality-free gateway to a unitary semantic system, where information about people is stored in an amodal format. Data obtained in patient VL (and to a lesser degree in StG) were at variance with this model because VL showed: (1) a very impaired familiarity for faces, contrasting with a spared familiarity for names, indicating that familiarity judgments are generated at the level of modality-specific recognition units and not at a supramodal PIN; (2) a prevalent impairment of person-specific information available from faces rather than from names also for people that (being recognized as familiar from both their face and their name) should be normally represented at the PINs level. This last finding is at variance with the hypothesis assuming that the PINs may provide a modality-free gateway to a unitary semantic system, where information about people is stored in an amodal format.

An array of cortical and subcortical structures have been implicated in the recognition of emotion from facial expressions. It remains unknown how these regions communicate as parts of a system to achieve recognition, but white matter tracts are likely critical to this process. We hypothesized that (1) damage to white matter tracts would be associated with recognition impairment and (2) the degree of disconnection of association fiber tracts [inferior longitudinal fasciculus (ILF) and/or inferior fronto-occipital fasciculus (IFOF)] connecting the visual cortex with emotion-related regions would negatively correlate with recognition performance. One hundred three patients with focal, stable brain lesions mapped onto a reference brain were tested on their recognition of six basic emotional facial expressions. Association fiber tracts from a probabilistic atlas were coregistered to the reference brain. Parameters estimating disconnection were entered in a general linear model to predict emotion recognition impairments, accounting for lesion size and cortical damage. Damage associated with the right IFOF significantly predicted an overall facial emotion recognition impairment and specific impairments for sadness, anger, and fear. One subject had a pure white matter lesion in the location of the right IFOF and ILF. He presented specific, unequivocal emotion recognition impairments. Additional analysis suggested that impairment in fear recognition can result from damage to the IFOF and not the amygdala. Our findings demonstrate the key role of white matter association tracts in the recognition of the facial expression of emotion and identify specific tracts that may be most critical.

We report a functional magnetic resonance imaging (fMRI) adaptation study of two well-described patients, DF and PS, who present face identity recognition impairments (prosopagnosia) following brain-damage. Comparing faces to non-face objects elicited activation in all visual areas of the cortical face processing network that were spared subsequent to brain damage. The common brain lesion in the two patients was in the right inferior occipital cortex, in the territory of the right "occipital face area" ('OFA'), which strengthens the critical role of this region in processing faces. Despite the lesion to the right 'OFA', there was normal range of sensitivity to faces in the right "fusiform face area" ('FFA') in both patients, supporting a non-hierarchical model of face processing at the cortical level. At the same time, however, sensitivity to individual face representations, as indicated by release from adaptation to identity, was abnormal in the right 'FFA' of both patients. This suggests that the right 'OFA' is necessary to individualize faces, perhaps through reentrant interactions with other cortical face sensitive areas. The lateral occipital area (LO) is damaged bilaterally in patient DF, who also shows visual object agnosia. However, in patient PS, in whom LO was spared, sensitivity to individual representations of non-face objects was still found in this region, as in the normal brain, consistent with her preserved object recognition abilities. Taken together, these observations, which fruitfully combine functional imaging and neuropsychology, place strong constraints on the possible functional organization of the cortical areas mediating face processing in the human brain.

Two experiments investigated attention of children with autism spectrum disorder (ASD) to faces and objects. In both experiments, children (7- to 15-year-olds) detected the difference between 2 visual scenes. Results in Experiment 1 revealed that typically developing children (n = 16) detected the change in faces faster than in objects, whereas children with ASD (n = 16) were equally fast in detecting changes in faces and objects. These results were replicated in Experiment 2 (n = 16 in children with ASD and 22 in typically developing children), which does not require face recognition skill. Results suggest that children with ASD lack an attentional bias toward others' faces, which could contribute to their atypical social orienting.

In the current study we describe J.M., a 15-year-old boy with a history of congenital brain abnormalities and concomitant visual-processing impairments. J.M.'s most prominent deficit is his impaired face recognition, but formal testing also revealed deficits in other domains of visual processing. One aspect that emerged from J.M.'s visual-processing assessment was a tendency to focus on local features and to rely on them for the encoding and identification of visual stimuli including geometric figures, objects, words, and inverted faces. In spite of this general tendency, he was impaired on tasks requiring the encoding of local features in upright faces. Moreover, his ability to distinguish between features in upright faces was significantly worse than that for inverted faces, the opposite pattern to that typically found in normal participants. What is it that keeps J.M. from applying his otherwise intact feature-based processing to upright faces? As proposed in previous reports of face inversion superiority in individuals with acquired face recognition impairments, we suggest that J.M.'s "inverted-face inversion effect" speaks for a specialized cognitive system that is mandatorily engaged by upright (but not inverted) faces, even when it is impaired and therefore maladaptive. In addition, since J.M. suffered from congenital brain abnormalities affecting the normal development of his face-processing skills, his performance suggests that specialized and mandatorily activated face-processing mechanisms are not entirely experience dependent, and that they can remain modular during development even if they don't function properly and are therefore maladaptive.

We report a psychophysiological study of "recognition without awareness" in patient 2354, who had severe but circumscribed atrophy in the occipitoparietal region bilaterally (caused by visual-variant Alzheimer's disease, documented by structural and functional neuroimaging) and an accompanying Balint syndrome that prevented her from recognizing the emotional valence of many highly charged negative visual scenes (e.g., a burned body). Despite this lack of overt recognition, patient 2354 nonetheless generated large amplitude skin conductance responses to highly charged negative pictures, demonstrating the same kind of recognition without awareness that has been reported previously in patients with bilateral occipitotemporal dysfunction and prosopagnosia [e.g., Tranel, D., & Damasio, A. R. (1985). Knowledge without awareness: an autonomic index of facial recognition by prosopagnosics. Science, 228, 1453-1454.]. Our case complements both previous evidence of covert, nonconscious recognition in patients with prosopagnosia, and previous behavioral studies of patients with Balint syndrome that have shown evidence of "preattentive" visual processing. The findings add to the small but important set of empirical observations regarding nonconscious visual processing in neurological patients, and indicate that recognition without awareness can occur in the setting of dorsal visual stream dysfunction and Balint syndrome. The findings in our patient suggest that she has patent pathways from higher-order visual cortices to autonomic effectors in the amygdala or hypothalamus, even though the results of such information processing are not made available to conscious awareness.

There is no known literature to guide the critical care nurse in the use of mirrors in patient care. This article explores how the author came to believe that mirrors were essential to nursing practice. Misconceptions and assumptions concerning mirrors are explored. A framework that conceptually explores the experience of viewing self in the mirror from the perspective of a person is presented. Five situations in which the mirror may be used in critical care are discussed. This article does not present an authoritative view on mirrors in nursing; rather, it is an invitation to dialogue about a unique element in the environment that may be used to enhance nursing care.

The association semantic dementia-amyotrophic lateral sclerosis has been rarely reported in the literature. We report a case study of a patient with a severe prosopagnosia in relation with semantic dementia associated, 12 months later, with a motor neuron disease.

We describe a patient who suddenly developed prosopometamorphopsia after a childbirth; she claimed that the left half of well-known and unfamiliar faces looked distorted. Brain MR was normal, whereas SPECT showed hypoperfusion of the left infero-lateral occipital cortex. No visual recognition defects for objects or faces were present. In three matching tasks with half-faces (Experiment 1), chimeric faces (Experiment 2), or chimeric objects (Experiment 3), the patient was impaired only when she matched pairs of chimeric faces differing in their left half; the same results were obtained after 1 year. This is the first behavioural demonstration of selective chronic metamorphopsia for the left side of faces, and provides new insights for models of face processing.

Frontotemporal dementia is an important neurodegenerative disorder accounting for a significant proportion of dementia cases with onset before 60 years of age. Apart from the well recognized behavioral changes the disease has many other distinctive features like predominant language involvement alone or associated features of motor neuron disease or parkinsonism etc. which at times may be the presenting manifestation itself. In the following article we describe a rare presenting manifestation; prosopagnosia, in the setting of frontotemporal degeneration.

A 58-year-old man with metastatic brain tumor in his right occipito-temporal region was operated, using craniectomy. He had no neurological symptoms preoperatively. The tumor was 2.5 cm in diameter with minor perifocal edema. Two days after total removal of the tumor, typical prosopagnosia appeared, in which he could not recognize his wife's face as well as faces of medical stuff. He could see them as a whole, and described them undistinguishably from each other. He used voices, movements and clothing to recognize a familiar person. His recognition and semantic knowledge of people were found to be intact and he could recognize certain parts of the face (e.g. the nose or the mouth). He could clearly see other parts of the body, the environment and other objects, in color. The prosopagnostic condition lasted for a few weeks and slowly disappeared. Prosopagnosia caused by surgical procedure has been rarely reported. Although postoperative prosopagnosia is likely to be transient, it should be recognized as a complication in occipito-temporal cortex.

This study explored structural correlates of immediate and delayed face recognition in 22 nonsurgical patients with nonlesional, unilateral mesial temporal lobe epilepsy (TLE, 10 left/12 right). We measured T2 relaxation time bilaterally in the hippocampus, the amygdala, and the fusiform gyrus. Apart from raised T2 values in the ipsilateral hippocampus, we found increased T2 values in the ipsilateral amygdala. Patients with right TLE exhibited impaired face recognition as a result of a decrease from immediate to delayed recognition. Higher T2 values in the right than left fusiform gyrus or hippocampus were related to worse immediate face recognition, but did not correlate with 24-hour face recognition. These preliminary results indicate that structural changes in the fusiform gyrus and hippocampus may influence immediate face recognition deficits, but have no linear influence on long-term face recognition in TLE. We suggest that long-term face recognition depends on a right hemispheric network encompassing structures outside the temporal lobe.

Objectives: A deficit in facial emotion recognition was described in patients with Alzheimer disease (AD). However, this issue has been underexplored in subjects with amnestic mild cognitive impairment (a-MCI). Thus, the authors aimed to determine whether a deficit in facial emotion recognition is present in a-MCI phase and whether this is intensity dependent. A secondary aim was to investigate relationships between facial emotion recognition and cognitive performances., Design: Case-control study., Setting: Memory clinic., Participants: Fifty a-MCI patients, 50 mild AD patients, and 50 comparison subjects (COM) were enrolled., Measurements: Information about facial emotion recognition was obtained from Penn Emotion Recognition Test. The Mental Deterioration Battery was used to measure cognitive impairment., Results: Mild AD patients were more impaired in the recognition of almost all emotional stimuli of all intensities than a-MCI and COM subjects. However, there was an increased progression only in low-intensity facial emotion recognition deficit from COM to a-MCI to mild AD patients. In particular, a-MCI subjects differed significantly from COM in low-intensity fearful face recognition performance. This deficit in a-MCI patients was explained by the short-term verbal memory impairment, whereas the same deficit in mild AD patients was explained by the long-term verbal memory impairment., Conclusions: Emotion recognition progresses from a deficit in low-intensity fearful facial recognition in a-MCI phase to a deficit in all intensities and emotions in mild AD. This could be an effect of the progressive degeneration of brain structures modulating emotional processing. An early detection of emotional impairment in MCI phases of dementia may have clinical implications.

Semantic dementia (SD) is a syndrome of progressive loss of semantic knowledge for objects and people. International criteria propose that SD be included in the frontotemporal lobar degeneration syndromes, with progressive non-fluent aphasia and frontotemporal dementia (FTD). However, several related syndromes have been defined that clinically and conceptually share both similarities and differences with SD: fluent progressive aphasia, progressive prosopagnosia, temporal variant of FTD. In order to establish a French consensus for the diagnosis and modalities of evaluation and follow-up of SD, a working group, composed of neurologists, neuropsychologists and speech-therapists, was established by the Groupe de réflexion sur les évaluations cognitives (GRECO). New criteria were elaborated, based on clinical, neuropsychological, and imaging data. They define typical and atypical forms of SD. A diagnosis of typical SD relies on an isolated and progressive loss of semantic knowledge, attested by a deficit of word comprehension and a deficit of objects and/or people identification, with imaging showing temporal atrophy and/or hypometabolism. SD is atypical if the deficit of semantic knowledge is present only within a single modality (verbal versus visual), or if non-semantic deficits (mild and not present at onset) and/or neurological signs, are associated with the semantic loss.

Acquired prosopagnosia varies in both behavioural manifestations and the location and extent of underlying lesions. We studied 10 patients with adult-onset lesions on a battery of face-processing tests. Using signal detection methods, we found that discriminative power for the familiarity of famous faces was most reduced by bilateral occipitotemporal lesions that involved the fusiform gyri, and better preserved with unilateral right-sided lesions. Tests of perception of facial structural configuration showed severe deficits with lesions that included the right fusiform gyrus, whether unilateral or bilateral. This deficit was most consistent for eye configuration, with some patients performing normally for mouth configuration. Patients with anterior temporal lesions had better configuration perception, though at least one patient showed a more subtle failure to integrate configural data from different facial regions. Facial imagery, an index of facial memories, was severely impaired by bilateral lesions that included the right anterior temporal lobe and marginally impaired by fusiform lesions alone; unilateral right fusiform lesions tended to spare imagery for facial features. These findings suggest that (I) prosopagnosia is more severe with bilateral than unilateral lesions, indicating a minor contribution of the left hemisphere to face recognition, (2) perception of facial configuration critically involves the right fusiform gyrus and (3) access to facial memories is most disrupted by bilateral lesions that also include the right anterior temporal lobe. This supports assertions that more apperceptive variants of prosopagnosia are linked to fusiform damage, whereas more associative variants are linked to anterior temporal damage. Next, we found that behavioural indices of covert recognition correlated with measures of overt familiarity, consistent with theories that covert behaviour emerges from the output of damaged neural networks, rather than alternative pathways. Finally, to probe the face specificity of the prosopagnosic defect, we tested recognition of fruits and vegetables: While face specificity was not found in most of our patients, the data of one patient suggested that this may be possible with more focal lesions of the right fusiform gyrus.

Individuals with Williams syndrome (WS) and autism are characterized by different social phenotypes but have been said to show similar atypicalities of face-processing style. Although the structural encoding of faces may be similarly atypical in these two developmental disorders, there are clear differences in overall face skills. The inclusion of both populations in the same study can address how the profile of face skills varies across disorders. The current paper explored the processing of identity, eye-gaze, lipreading, and expressions of emotion using the same participants across face domains. The tasks had previously been used to make claims of a modular structure to face perception in typical development. Participants with WS (N=15) and autism (N=20) could be dissociated from each other, and from individuals with general developmental delay, in the domains of eye-gaze and expression processing. Individuals with WS were stronger at these skills than individuals with autism. Even if the structural encoding of faces appears similarly atypical in these groups, the overall profile of face skills, as well as the underlying architecture of face perception, varies greatly. The research provides insights into typical and atypical models of face perception in WS and autism.

The perception of a face allows us to recognize the person, infer his or her emotional state, better understand what the person is saying, and derive general information, such as age and gender. This unique visual stimulus has generated a wealth of research, and subsequently theoretical and methodological debate. This special issue brings together 16 original papers that show the extraordinary diversity and fruitfulness of the approaches now being pursued. They are aimed at understanding different aspects of face perception in populations ranging from healthy children to adults with brain lesions and with techniques covering the entire spectrum from paper-and-pencil tests to functional brain imaging. Together, these contributions provide an insightful overview of the current state of research on face perception and exemplify the questions that dominate the field. To one such question, whether 'face perception' is a special issue in the broad field of the cognitive neurosciences, the answer is clearly yes!

Although most adults are considered experts in face recognition, brain trauma can produce a selective loss in this ability, a condition referred to as prosopagnosia. This study examined the processing strategies of prosopagnosic patients LR and HH using the Face Dimensions Test. In this test, featural and configural information in the upper and lower halves of the face was parametrically varied and sensitivity to these changes measured. We found that relative to age-matched control participants, LR and HH exhibited an impaired ability to discriminate differences in the eye region, but a preserved ability to detect featural and configural differences in the mouth region. This pattern of impairment and sparing was demonstrated in tests of direct perception and immediate memory. The obtained findings demonstrate that prosopagnosia does not necessarily cause a global impairment to face perception, but a selective impairment to the perception of information in the upper half of the face.

Voices, in addition to faces, enable person identification. Voice recognition has been shown to evoke a distributed network of brain regions that includes, in addition to the superior temporal sulcus (STS), the anterior temporal pole, fusiform face area (FFA), and posterior cingulate gyrus (pCG). Here we report an individual (MS) with acquired prosopagnosia who, despite bilateral damage to much of this network, demonstrates the ability to distinguish voices of several well-known acquaintances from voices of people that he has never heard before. Functional magnetic resonance imaging (fMRI) revealed that, relative to speech-modulated noise, voices rated as familiar and unfamiliar by MS elicited enhanced haemodynamic activity in the left angular gyrus, left posterior STS, and posterior midline brain regions, including the retrosplenial cortex and the dorsal pCG. More interestingly, relative to noise and unfamiliar voices, the familiar voices elicited greater haemodynamic activity in the left angular gyrus and medial parietal regions including the dorsal pCG and precuneus. The findings are consistent with theories implicating the pCG in recognizing people who are personally familiar, and furthermore suggest that the pCG region of the voice identification network is able to make functional contributions to voice recognition even though other areas of the network, namely the anterior temporal poles, FFA, and the right parietal lobe, may be compromised.

Acquired prosopagnosia is usually associated with bilateral or right-sided lesions of the occipital or temporal lobes. In rare cases of prosopagnosia after left-sided lesions in left-handed subjects, it is attributed to a reversed hemispheric specialization for face processing. This study examines the face-processing functions of a left-handed prosopagnosic patient with a left-sided lesion affecting the region of the occipital face area and possibly the fusiform face area, to contrast his deficits with those of prosopagnosic patients with right-hemispheric lesions. Similar to those patients, he has a moderately severe reduction in familiarity judgments, is impaired in processing face configuration, and shares with some of those patients a greater failure to process eye than mouth information, indicating an altered pattern of facial saliency. He has a mild reduction in the identification of exemplars of non-face objects. Unlike those patients, he has better residual familiarity on a two-alternative forced-choice task and can processing facial configuration if given more time, indicating a reduction in efficiency rather than a severe limitation. He has more difficulty accessing semantic-biographic information from names. He has trouble with facial feature imagery but not imagery for global face shape. Thus this subject's deficits represent a combination of impaired familiarity and configuration processing (normally right-sided functions in right-handed subjects), and impaired feature processing and access to semantic-biographic information (normally left-sided functions). His prosopagnosia likely reflects partially anomalous rather than reversed lateralization of hemispheric perceptual functions.

Two patients with large lesions of the medial temporal lobe were given four tests of semantic knowledge that could only have been acquired after the onset of their amnesia. In contrast to previous studies of postmorbid semantic learning, correct answers could be based on a simple, nonspecific sense of familiarity about single words, faces, or objects. According to recent computational models (for example, Norman and O'Reilly (2003) Psychol Rev 110:611-646), this characteristic should be optimal for detecting the kind of semantic learning that might be supported directly by the neocortex. Both patients exhibited some capacity for new learning, albeit at a level substantially below control performances. Notably, the correct answers appeared to reflect declarative memory. It was not the case that the correct answers simply popped out in some automatic way in the absence of any additional knowledge about the items. Rather, the few correct choices made by the patients tended to be accompanied by additional information about the chosen items, and the available knowledge appeared to be similar qualitatively to the kind of factual knowledge that healthy individuals gradually acquire over the years. The results are consistent with the idea that neocortical structures outside the medial temporal lobe are able to support some semantic learning, albeit to a very limited extent. Alternatively, the small amount of learning detected in the present study could depend on tissue within the posterior medial temporal lobe that remains intact in both patients., ((c) 2008 Wiley-Liss, Inc.)

We compared six cases of congenital prosopagnosia to unimpaired participants using standardized test batteries, tailor-made experimental paradigms, and clinical questionnaires. Every prosopagnosic participant displayed deficits in recognizing famous faces and retaining novel faces over short periods of time. Other aspects of face perception such as judgment of emotional expression, speech reading and memory for faces and names were impaired to a lesser degree or only in single cases. No evidence was found for general visual deficits or social dysfunctions. Two of our six cases are first order relatives, and a further three report first-order relatives suffering from prosopagnosic symptoms. The results are in line with the idea of a genetic component to congenital prosopagnosia.

Primary Objective: To review the literature of affect recognition for persons with traumatic brain injury (TBI). It is suggested that impairment of affect recognition could be a significant problem for the TBI population and treatment strategies are recommended based on research for persons with autism., Main Outcomes and Results: Research demonstrates that persons with TBI often have difficulty determining emotion from facial expressions. Studies show that poor interpersonal skills, which are associated with impaired affect recognition, are linked to a variety of negative outcomes. Theories suggest that facial affect recognition is achieved by interpreting important facial features and processing one's own emotions. These skills are often affected by TBI, depending on the areas damaged. Affect recognition impairments have also been identified in persons with autism. Successful interventions have already been developed for the autism population. Comparable neuroanatomical and behavioural findings between TBI and autism suggest that treatment approaches for autism may also benefit those with TBI., Conclusions: Impaired facial affect recognition appears to be a significant problem for persons with TBI. Theories of affect recognition, strategies used in autism and teaching techniques commonly used in TBI need to be considered when developing treatments to improve affect recognition in persons with brain injury.

Prosopagnosia is one of the many forms of visual associative agnosia, in which familiar faces lose their distinctive association. In the case of prosopagnosia, the ability to recognize familiar faces is lost, due to lesions in the medial occipitotemporal region. In "associative" prosopagnosia, the perceptual system seems adequate to allow for recognition, yet recognition cannot take place. Our hypothesis is that a possible cause of associative prosopagnosia might be the occurrence of Dynamic attractors in the brain's auto-associative circuits. We present a biologically plausible model composed of two stages: Pre-processing and face recognition. In the first stage, the face image is passed through Gabor filters which model the kind of visual processing carried out by the simple and complex cells of the primary visual cortex of higher mammals and the resulting features are fed into a Pseudo-inverse associative neural network for the recognition task. Next, we damage the network by reducing self-connections below a certain threshold in order to create dynamic attractors and hence hinder the networks ability to recognize familiar faces (faces already learned). Results obtained from simulations show that the resulting network responses are very similar to those of associative prosopagnosic patients. We conclude that the problems concerning associative prosopagnosia may partly be explained through the concepts of dynamic attractors. Although there is no known cure for prosopagnosia, we believe that the focus of any treatment should be to help the individual with prosopagnosia develop compensatory strategies for remembering faces. Adults with prosopagnosia as a result of stroke or brain trauma can be retrained to use other clues to identify faces. And a cure for children born with prosopagnosia might eventually rely on reinforcement techniques that reward them for paying attention to faces during early childhood. Reinforcement learning from examples of patterns to be classified using habituation and association would create lower dimensional local basins in the brain, which would form a global attractor landscape with one basin for each face. These local basins would eventually constitute dynamical memories that solve difficult problems in classifying and recognizing faces.

We review recent researches in neural mechanisms of facial recognition in the light of three aspects: facial discrimination and identification, recognition of facial expressions, and face perception in itself. First, it has been demonstrated that the fusiform gyrus has a main role of facial discrimination and identification. However, whether the FFA (fusiform face area) is really a special area for facial processing or not is controversial; some researchers insist that the FFA is related to 'becoming an expert' for some kinds of visual objects, including faces. Neural mechanisms of prosopagnosia would be deeply concerned to this issue. Second, the amygdala seems to be very concerned to recognition of facial expressions, especially fear. The amygdala, connected with the superior temporal sulcus and the orbitofrontal cortex, appears to operate the cortical function. The amygdala and the superior temporal sulcus are related to gaze recognition, which explains why a patient with bilateral amygdala damage could not recognize only a fear expression; the information from eyes is necessary for fear recognition. Finally, even a newborn infant can recognize a face as a face, which is congruent with the innate hypothesis of facial recognition. Some researchers speculate that the neural basis of such face perception is the subcortical network, comprised of the amygdala, the superior colliculus, and the pulvinar. This network would relate to covert recognition that prosopagnosic patients have.

We review recent researches in neural mechanisms of facial recognition in the light of three aspects: facial discrimination and identification, recognition of facial expressions, and face perception in itself. First, it has been demonstrated that the fusiform gyrus has a main role of facial discrimination and identification. However, whether the FFA (fusiform face area) is really a special area for facial processing or not is controversial; some researchers insist that the FFA is related to 'becoming an expert' for some kinds of visual objects, including faces. Neural mechanisms of prosopagnosia would be deeply concerned to this issue. Second, the amygdala seems to be very concerned to recognition of facial expressions, especially fear. The amygdala, connected with the superior temporal sulcus and the orbitofrontal cortex, appears to operate the cortical function. The amygdala and the superior temporal sulcus are related to gaze recognition, which explains why a patient with bilateral amygdala damage could not recognize only a fear expression; the information from eyes is necessary for fear recognition. Finally, even a newborn infant can recognize a face as a face, which is congruent with the innate hypothesis of facial recognition. Some researchers speculate that the neural basis of such face perception is the subcortical network, comprised of the amygdala, the superior colliculus, and the pulvinar. This network would relate to covert recognition that prosopagnosic patients have.

A 67-year-old, right-handed woman became unable to recognize familiar faces following a period of nonconvulsive status epilepticus. Neuropsychological assessment revealed a relatively selective impairment of familiar face recognition in the absence of low-level visual deficits or widespread cognitive impairment. MRI scanning demonstrated an isolated lesion, probably a venous angioma, involving the left fusiform gyrus, mirror-symmetrical to the site typically linked to prosopagnosia. Potential explanations for the patient's prosopagnosia include seizure-related damage to a left fusiform region required for fully competent face recognition and damage to the contralateral fusiform gyrus via interhemispheric connections. Focal neuropsychological deficits in patients with refractory partial epilepsy who develop nonconvulsive status epilepticus may be underdiagnosed.

Visual-spatial agnosis, praxis deficits and hallucinations can be the features of subacute sclerosing panencephalitis (SSPE) in the early period. This study describes a 15-year-old boy with SSPE presenting with visual agnosia, prosopagnosia, simultanagnosia, optic ataxia, and oculomotor apraxia which are compatible with Balint syndrome. MRI revealed heterogenous and abnormal signal changes in the bilateral parieto-occipital areas. The signals were more prominent on the left. The case discussed herein is important because he was diagnosed as Balint's syndrome by means of clinical and neuroradiological findings before the onset of known symptomatology as dementia/myoclonus of SSPE. The case is also illustrative of the need to emphasize the prompt evaluation of a patient's cortical features before clinical progression becomes apparent. This evaluation should be performed in the early period if correct diagnosis is to be reached.

Background: Posterior cortical atrophy (PCA) is a progressive dementia characterized by prominent disorders of higher visual processing, affecting both dorsal and ventral streams to cause Balint's syndrome, alexia, and visual agnosia., Objective: To define the cognitive profile of PCA and compare to the typical, primary amnestic dementia of the Alzheimer's type (DAT)., Methods: The authors used standard cognitive tests and a novel battery designed to reflect dysfunction in both ventral (Object, Face & Color Agnosia Screen [OFCAS]) and dorsal (complex pictures and compound stimuli) visual streams. The authors identified 19 patients with PCA and compared their performance to a matched group of patients with DAT and normal controls., Results: Patients with PCA were younger with marked impairment in visuospatial tasks, reading, and writing but relative preservation of memory compared to DAT using standard tests. Dorsal stream signs were most prevalent among the patients with PCA with no pure ventral stream syndromes found. All novel tests distinguished reliably between subjects with complex picture descriptions and processing of compound stimuli showing the most significant differences compared to DAT., Conclusions: PCA is predominantly a dorsal stream syndrome, distinct from typical DAT, which involves occipitotemporal regions over time.

A woman produced spontaneous confabulations after rupture of an anterior communicating artery aneurysm. She confused currently irrelevant with currently relevant information in implicit memory; confabulations about people concerned only new acquaintances; false reality could be induced by an intensive 5-minute discussion; and in a recognition task, she confused false repetitions in another modality with real item repetitions. The findings support the theory that the defect causing spontaneous confabulation precedes conscious memory processing.

One of the most impressive disorders following brain damage to the ventral occipitotemporal cortex is prosopagnosia, or the inability to recognize faces. Although acquired prosopagnosia with preserved general visual and memory functions is rare, several cases have been described in the neuropsychological literature and studied at the functional and neural level over the last decades. Here we tested a brain-damaged patient (PS) presenting a deficit restricted to the category of faces to clarify the nature of the missing and preserved components of the face processing system when it is selectively damaged. Following learning to identify 10 neutral and happy faces through extensive training, we investigated patient PS's recognition of faces using Bubbles, a response classification technique that sampled facial information across the faces in different bandwidths of spatial frequencies [Gosselin, F., & Schyns, P. E., Bubbles: A technique to reveal the use of information in recognition tasks. Vision Research, 41, 2261-2271, 2001]. Although PS gradually used less information (i.e., the number of bubbles) to identify faces over testing, the total information required was much larger than for normal controls and decreased less steeply with practice. Most importantly, the facial information used to identify individual faces differed between PS and controls. Specifically, in marked contrast to controls, PS did not use the optimal eye information to identify familiar faces, but instead the lower part of the face, including the mouth and the external contours, as normal observers typically do when processing unfamiliar faces. Together, the findings reported here suggest that damage to the face processing system is characterized by an inability to use the information that is optimal to judge identity, focusing instead on suboptimal information.

Introduction: The association of prosopagnosia and false recognition of faces is unusual and contributes to our understanding of the generation of facial familiarity., Method: A 67-year-old man with a left prefrontal traumatic lesion, developed a temporal variety of fronto-temporal dementia (semantic dementia) with amyotrophic lateral sclerosis. Cerebral imagery demonstrated a bilateral, temporal anterior atrophy predominating in the right hemisphere. The main cognitive signs consisted in severe difficulties to recognize faces of familiar people (prosopagnosia), associated with systematic false recognition of unfamiliar people., Result: Neuropsychological testing indicated that the prosopagnosia probably resulted from the association of an associative/mnemonic mechanism (inability to activate the Face Recognition Units (FRU) from the visual input) and a semantic mechanism (degradation of semantic/biographical information or deconnexion between FRU and this information). At the early stage of the disease, the patient could activate residual semantic information about individuals from their names, but after a 4-year course, he failed to do so. This worsening could be attributed to the extension of the degenerative lesions to the left temporal lobe. Familiar and unfamiliar faces triggered a marked feeling of knowing. False recognition concerned all the unfamiliar faces, and the patient claimed spontaneously that they corresponded to actors, but he could not provide any additional information about their specific identities. The coexistence of prosopagnosia and false recognition suggests the existence of different interconnected systems processing face recognition, one intended to identification of individuals, and the other producing the sense of familiarity. Dysfunctions at different stages of one or the other of these two processes could result in distortions in the feeling of knowing., Conclusion: From this case and others reported in literature, we propose to complete the classical model of face processing by adding a pathway linked to limbic system and frontal structures. This later pathway could normally emit signals for familiarity, essentially autonomic, in response to the familiar faces. These signals, primitively unconscious, secondly reach consciousness and are then integrated by a central supervisor system which evaluates and verifies identity-specific biographical information in order to make a decision about the sense of familiarity.

Naming problems are common in patients with dominant temporal lobe epilepsy (TLE) and anterior temporal lobectomy (ATL). Descriptive naming may be an especially useful procedure for the presurgical workup of candidates for ATL, given its sensitivity for detecting subtle naming problems in TLE and its localization to anterior temporal regions that are commonly targeted for resection in ATL. This study provides normative data pertaining to difficulty level (accuracy and reaction time) on 372 descriptive naming items in four conceptual categories: common non-living, common living, unique non-living, and unique living things. These data will be useful to investigators who wish to develop protocols for clinical assessment or stimuli for functional imaging paradigms aimed at assessing the function of the anterior temporal lobes.

Background: Patients with prosopagnosia from occipitotemporal lesions have impaired perception of the configuration of facial features. This may be an example of impaired "within-object" spatial coding, which others propose to be distinct from "between-object" spatial coding., Objective: To determine whether the prosopagnosic deficit in perceiving spatial configuration was specific to within-face and not between-face spatial coding and whether the deficit was face-selective or extended to objects other than faces., Methods: Six prosopagnosic patients were tested using an oddity paradigm in which they detected which of three simultaneously seen stimuli was an altered target. In the "within-face" task, the target face had altered interocular distance or mouth position. In the "between-face" task, the target face was located farther away from the other two. In the "within-object" task, the stimulus was a two-dot pattern, and the target pattern had altered interdot distance., Results: Spatial judgments were impaired within faces for all six patients and within the two-dot pattern for five of six patients. However, all six had normal between-face spatial perception., Conclusions: Impaired perception of spatial relations in prosopagnosia is selective to the spatial structure within individual objects and spares the perception of spatial location of objects. It is not specific to faces. It reveals a process involved in analyzing object structure, consistent with the patients' deficits in recognizing facial identity, and illustrates a different type of "visuospatial" defect.