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At least 19 recordsLinked to original sources
PubMed2007

A detailed investigation of facial expression processing in congenital prosopagnosia as compared to acquired prosopagnosia.

Whether the ability to recognize facial expression can be preserved in the absence of the recognition of facial identity remains controversial. The current study reports the results of a detailed investigation of facial expression recognition in three congenital prosopagnosic (CP) participants, in comparison with two patients with acquired prosopagnosia (AP) and a large group of 30 neurologically normal participants, including individually age- and gender-matched controls. Participants completed a fine-grained expression recognition paradigm requiring a six-alternative forced-choice response to continua of morphs of six different basic facial expressions (e.g. happiness and surprise). Accuracy, sensitivity and reaction times were measured. The performance of all three CP individuals was indistinguishable from that of controls, even for the most subtle expressions. In contrast, both individuals with AP displayed pronounced difficulties with the majority of expressions. The results from the CP participants attest to the dissociability of the processing of facial identity and of facial expression. Whether this remarkably good expression recognition is achieved through normal, or compensatory, mechanisms remains to be determined. Either way, this normal level of performance does not extend to include facial identity.

Adult↗
PubMedDate not supplied

[Prosopagnosia: is it a single or a multiple entity?].

INTRODUCTION: The prosopagnosia has generally been defined as an incapacity to recognize familiar faces, or faces previously known, due to certain lesions to certain areas of the cerebral cortex. Yet it seems that there is no universal consensus neither on its definition nor in relation to the specific lesions that might cause it. There seems to be no consensus either around the criteria that might enable us to identify different types of prosopagnosia. OBJECTIVE: We make an attempt to revise the definition of prosopagnosia and to see if it is appropriate to consider it as a single entity or, on the contrary, we are able to differentiate specific types of prosopagnosia according to its origin, brain lesion associated with it or the patients characteristics. On the other hand, we questioned ourselves whether different exams usually utilized for the identification of prosopagnosia in fact measure the same concept. CONCLUSIONS: We propose that we could distinguish different types of prosopagnosia with different clinical characteristics. Then we went on to differentiate between developed prosopagnosias and acquired prosopagnosias by bilateral brain lesion as opposed with those associated with a fundamentally aperceptive deficit, as opposed to those linked with a fundamentally associative deficit. Lastly, we propose that different types of exams of recognition and identification can measure distinct aspects linked to prosopagnosia.

Brain Damage, Chronic↗
PubMed2004

The covert priming effect of faces in prosopagnosia.

BACKGROUND: There are many methods of testing covert face recognition in prosopagnosia, but it is not clear whether different types of covert recognition share a common mechanism. OBJECTIVE: To determine whether direct forced-choice techniques and indirect face-priming methods yielded similar behavioral estimates of covert ability in a series of prosopagnosic patients. METHODS: The authors tested seven control subjects and seven prosopagnosic patients. Six patients had an apperceptive prosopagnosia: one with childhood onset, three with bilateral lesions, and two with unilateral occipitotemporal lesions. The last had an associative prosopagnosia from bilateral anterior temporal lesions. The direct tests of covert function involved sorting faces by occupation or the forced choosing of which of two faces was famous with a name cue. The indirect test assessed name classification by occupation after priming with a facial stimulus. RESULTS: In normal subjects, the chief priming effect was facilitation by the true face. In the six patients with apperceptive prosopagnosia, direct covert measures were correlated with the face-priming effect, with better covert ability in patients with unilateral posterior lesions. In the patient with associative prosopagnosia, there was a dissociation between excellent direct covert function and absent face priming. CONCLUSIONS: Direct and indirect covert functions likely share similar mechanisms in patients with apperceptive prosopagnosia and may reflect residual activity in anterior and left hemispheric components of the normal face-processing network. However, face priming may be ineffectual in patients with severely degraded facial memories from anterior temporal damage. This may indicate a difference between residual patterns of face-related activity in associative and apperceptive prosopagnosia.

Adult↗
PubMed2001

Covert recognition in acquired and developmental prosopagnosia.

BACKGROUND: Some patients with prosopagnosia have covert recognition, meaning that they retain some familiarity or knowledge of facial identity of which they are not aware. OBJECTIVE: To test the hypothesis that prosopagnosic patients with right occipitotemporal lesions and impaired face perception lack covert processing, whereas patients with associative prosopagnosia and bilateral anterior temporal lesions possess it. METHODS: Eight patients with prosopagnosia were tested with a battery of four face recognition tests to determine their ability to discriminate between famous and unknown faces. RESULTS: Measures of overt familiarity revealed better residual discrimination in patients with acquired prosopagnosia than in those with the developmental form. With forced-choice methods using famous faces paired with unknown faces, no patient demonstrated covert familiarity. However, when the semantic cue of the name of the famous face was provided, covert processing was present in all five patients with acquired prosopagnosia, including the three with extensive right-sided lesions and impaired perceptual discrimination of facial configuration. Sorting unrecognized faces by occupation was also performed above chance in three of these five patients. In contrast, none of the three patients with developmental prosopagnosia had covert processing, even though two demonstrated flawless performance on similar tests of name (rather than face) recognition. Overt familiarity correlated highly with the degree of covert recognition. CONCLUSIONS: Extensive right occipitotemporal lesions with significant deficits in face perception are not incompatible with covert face processing. Covert processing is absent in developmental prosopagnosia, because this condition likely precludes the establishment of a store of accurate facial memories. The presence of covert processing correlates with the degree of residual overt familiarity, indicating that these are related phenomena.

Adult↗
PubMed1985

Left hemispheric functional compensation in prosopagnosia? A tachistoscopic study with unilaterally lesioned patients.

Clinical observations suggest left hemispheric compensation for prosopagnosia in patients with isolated right posterior lesions. To test this hypothesis we investigated six patients with right posterior lesions, three with and three without prosopagnosia, with a series of tachistoscopic matching experiments. Faces with and without paraphernalia, shapes, objects and words were presented at different exposure durations (unlimited, 1000, 200, 50 and 20 ms). Prosopagnosia patients performed better than non-prosopagnosia patients if pure faces (eyes, nose and mouth only) were presented for an unlimited time, but performed worse than non-prosopagnosia patients if exposure duration was reduced. Patients with prosopagnosia were especially handicapped when required to match emotional expressions. Both patient groups had no difficulty in matching objects and words, even at short exposure durations. The results are discussed with respect to a possible left hemispheric compensation in prosopagnosia patients.

Adult↗
PubMed1989

[Non-verbal facial and topographic visual object agnosia--a problem of familiarity in prosopagnosia and topographic disorientation].

In recent years, prosopagnosia is defined as the "loss of ability to recognize the well-acquainted persons like the family members by their physiognomy." There are many reports based on this definition. However, from the viewpoint of symptomatology, there are many problems not entirely solved yet. And the mechanism of its manifestation is not clearly explained. Topographic disorientation, which often accompanies prosopagnosia, is studied even less. From the results of the postmortem examination in the literature, bilateral occipito-temporal lesions have been known to cause prosopagnosia. However, the recent radiographical examination by the computed tomography revealed that the prosopagnosia is also caused by the right occipito-temporal lesions only. We experienced a case with prosopagnosia and topographic disorientation which were considered to be caused by infarction in the territory of the right posterior cerebral artery. Detailed symptomatological, morphological and functional examinations were carried out by means of various psychological testing, X-ray computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET). The patient was a 70-year-old right-handed man who suffered from sudden visual loss on both eyes, and was admitted to our hospital after four weeks. On examination, a decrease of visual acuity and right homonymous hemianopsia were recognized. When visual acuity was recovered, he was unable to recognize the faces of his relatives and friends, with whom he has been well acquainted for many years. He also found his own house, the buildings and streets around it as entirely unfamiliar. Seven months after the onset of the disease, examination showed he had definite prosopagnosia and topographic disorientation.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed2004

Perceptual functions in prosopagnosia.

Some patients with prosopagnosia may have an apperceptive basis to their recognition defect. Perceptual abnormalities have been reported in single cases or small series, but the causal link of such deficits to prosopagnosia is unclear. Our goal was to identify candidate perceptual processes that might contribute to prosopagnosia, by subjecting several prosopagnosic patients to a battery of functions that may be necessary for accurate facial perception. We tested seven prosopagnosic patients. Three had unilateral right occipitotemporal lesions, two had bilateral posterior occipitotemporal lesions, and one had right anterior-to-occipital temporal damage along with a small left temporal lesion. These lesions all included the fusiform face area, in contrast to one patient with bilateral anterior temporal lesions. Most patients had impaired performance on face-matching tests and difficulty with subcategory judgments for non-face objects. The most consistent deficits in patients with lesions involving the fusiform face area were impaired perception of spatial relations in dot patterns and reduced contrast sensitivity in the 4 to 8 cycles deg(-1) range. Patients with bilateral lesions were impaired in saturation discrimination. Luminance discrimination was normal in all but two patients, and spatial resolution was uniformly spared. Curvature and line-orientation discrimination were impaired in only one patient, who also had the most difficulty with more basic-level object recognition. We conclude that deficits in luminance, spatial resolution, curvature, line orientation, and contrast at low spatial frequencies are unlikely to contribute to apperceptive prosopagnosia. More relevant may be contrast sensitivity at higher spatial frequencies and the analysis of object spatial structure. Deficits in these functions may impair perception of subtle variations in object shape, and may be one mechanism by which the recognition defect in prosopagnosia can extend to other classes of object subcategorization.

Adult↗
PubMed2002

Lesions of the fusiform face area impair perception of facial configuration in prosopagnosia.

BACKGROUND: Prosopagnosia, the inability to recognize faces, is associated with medial occipitotemporal lesions, especially on the right. Functional imaging has revealed a focal region in the right fusiform gyrus activated specifically during face perception. OBJECTIVE: The study attempted to determine whether lesions of this region were associated with defects in face perception in patients with prosopagnosia. METHODS: Five patients with acquired prosopagnosia were tested. They were asked to discriminate faces in which the spatial configuration of features had been altered. This was contrasted with their discrimination of changes in feature color, an alteration that does not affect spatial relations. RESULTS: All four patients whose lesions included the right fusiform face area were severely impaired in discriminating changes in the spatial position of features. The one patient with anterior bilateral lesions was normal in this perceptual ability. For three of the five patients, accuracy was normal for changes in eye color. When subjects knew that only changes in mouth position would be shown, performance improved markedly in two of the four patients who were impaired in the initial test. CONCLUSION: Perception of facial configuration is impaired in patients with prosopagnosia whose lesions involve the right fusiform gyrus. This deficit is especially manifest when attention must be distributed across numerous facial elements. It does not occur with more anterior bilateral temporal lesions. Loss of this ability may contribute to the recognition defect in some forms of prosopagnosia.

Adult↗
PubMed1988

Prosopagnosia and agnosia for noncanonical views. An autopsied case.

It has been postulated that for prosopagnosia to occur, bilateral lesions of the central visual system are usually necessary. All but 1 of the 10 previously documented cases that came to autopsy showed this pattern. However, the long survival period after the onset of prosopagnosia in most of these patients limits the value of the autopsy findings for clinicopathological correlation. A patient is presented who died 10 days after she had developed prosopagnosia, topographagnosia and an agnosia for real objects seen from noncanonical views. These clinical symptoms corresponded directly to the autopsy finding of a recent large occipitotemporal ischaemic infarct in the territory of the right posterior cerebral artery. An additional right frontal infarct and a cortical microinfarct in a deep left lateral parieto-occipital sulcus were both old lesions and had passed unnoticed clinically. This first report of a direct clinicopathological correlation between a fresh right posterior lesion and prosopagnosia demonstrates that bilateral involvement of the visual system is not a prerequisite for prosopagnosia.

Aged↗
PubMed2006

Gaze behaviour in hereditary prosopagnosia.

Prosopagnosia is the inability to recognize someone by the face alone in the absence of sensory or intellectual impairment. In contrast to the acquired form of prosopagnosia we studied the congenital form. Since we could recently show that this form is inherited as a simple monogenic trait we called it hereditary form. To determine whether not only face recognition and neuronal processing but also the perceptual acquisition of facial information is specific to prosopagnosia, we studied the gaze behaviour of four hereditary prosopagnosics in comparison to matched control subjects. This rarely studied form of prosopagnosia ensures that deficits are limited to face recognition. Whereas the control participants focused their gaze on the central facial features, the hereditary prosopagnosics showed a significantly different gaze behaviour. They had a more dispersed gaze and also fixated external facial features. Thus, the face recognition impairment of the hereditary prosopagnosics is reflected in their gaze behaviour.

Adult↗
PubMed2003

Transient postoperative prosopagnosia.

A 23-year-old right-handed woman developed isolated transient prosopagnosia following surgical resection of a right posterior temporal seizure focus. At 18 years of age she had developed secondarily generalized tonic-clonic seizures. Preoperative neuropsychological evaluation was normal, and neurological examination revealed only a left superior quadrant achromatopsia. MRI revealed a circumscribed lesion in the right inferolateral temporo-occipital junction. Following surgery she was agitated for 36 hours, and afterward, when her attention and orientation improved, she was unable to recognize familiar faces. She could, however, recognize familiar voices. Her prosopagnosia resolved over the next 6-7 days. This case demonstrates that isolated prosopagnosia can occur in patients with lesions restricted to the right inferior posterior temporal-anterior occipital region. The temporary nature of the prosopagnosia may result from postsurgical tissue injury, including focal cerebral edema, with compensation by ipsilateral or contralateral areas.

Adult↗
PubMed2003

Covert matching of unfamiliar faces in a case of prosopagnosia: an ERP study.

In addition to their deficit in overt face recognition, patients with prosopagnosia also have difficulties in matching sequentially presented unfamiliar faces. Here we assessed the possibility that covert matching of faces was present in a case with prosopagnosia using event-related potentials (ERPs). The participants (patient FE and normal controls) were challenged with a face-identity matching task, in which they decided whether two sequentially presented photographs of unfamiliar faces represented the same person. Only internal face features were used and the two faces in a pair differed in emotional expression. FE failed to overtly match these stimuli. In contrast, the ERPs revealed evidence of covert matching. If the two faces within a pair of stimuli depicted different posers, then the response to the second face contained an enhanced N300 compared to the situation where the identity of the faces was the same. The latency of the N300 was the same as a similar component found in controls. These results suggest that some cases with prosopagnosia have a covert ability to match unfamiliar faces, with similar temporal dynamics as controls, which in contrast with the idea that a generalized slowing of face processing occurs in all cases of prosopagnosia.

Aged↗
PubMed2005

[False recognition of faces associated with fronto-temporal dementia with prosopagnosia].

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.

Aged↗
PubMed2003

Developmental prosopagnosia: a review.

This article reviews the published literature on developmental prosopagnosia, a condition in which the ability to recognize other persons by facial information alone has never been acquired. Due to the very low incidence of this syndrome, case reports are sparse. We review the available data and suggest assessment strategies for patients suffering from developmental prosopagnosia. It is suggested that developmental prosopagnosia is not a unitary condition but rather consists of different subforms that can be dissociated on the grounds of functional impairments. On the basis of the available evidence, hypotheses about the aetiology of developmental prosopagnosia as well as about the selectivity of deficits related to face recognition are discussed.

Brain↗
PubMed1989

Prosopagnosia in a right hemispherectomized patient.

The first reported case of prosopagnosia in a right hemispherectomized woman, B.M., whose intellectual and cognitive functions were otherwise normal or only slightly impaired, is presented. She was totally unable to identify, and to experience a sense of familiarity with, faces of persons she knew, but she could evoke semantic information about them and retrieve their names from visual contextual cues. She was unaware that she was lacking face-recognition skills and that faces alone could be used to access the identity of individuals. The functional nature of her deficit was investigated through sensory, perceptual, memory, and learning tasks to determine the level at which her prosopagnosic disturbance occurred. She was defective at resolving low spatial-frequency information, but this was insufficient to explain the selectivity of her impairment. She was able to carry out cognitive operations specific to faces as long as facial identity did not have to be ascertained, and she performed as well as control subjects at deriving information about the gender, age, and emotion of faces. She was impaired at matching different views of the same faces, and multidimensional scaling analysis of dissimilarity judgements between faces indicated an inability to combine the component features into a configurational facial representation that would uniquely define each face. In contrast to recently reported cases of prosopagnosia, B.M. showed no sign of covert recognition of known faces in a learning task, and there was no indication that she could, even for a few seconds, store a faithful facial representation. The occurrence of prosopagnosia in this hemispherectomized patient confirms that this deficit can emerge without damage to the left hemisphere, and her unawareness of her deficit, which had remained unnoticed for several years, raises the possibility that other hemispherectomized patients may be prosopagnosic. The pattern of cognitive impairments displayed by B.M. indicates a perceptual basis to her disturbance and is discussed in relation to other cases of prosopagnosia.

Adult↗
PubMed1991

[Prosopagnosia. A rare disorder of visual perception].

Prosopagnosia is a rare neurological sign, characterized by disturbance of recognition of faces. It is important to remember that prosopagnosia can appear as a result of a brain injury, and as such may be a major disability to the patient. We report a case of a nine year old boy with prosopagnosia due to brain injury at the age of 18 months. The main injury was localized to the boy's left hemisphere, but his right hemisphere was probably also affected. Most post mortem examinations of patients suffering from prosopagnosia show bilateral or right-sided parietal, temporal and occipetal pathological changes.

Agnosia↗
PubMed1976

[Paroxystic auto-prosopagnosia and epilepsy. Physio-pathological correlation or chance association?].

A case of isolated, pure and paroxystic auto-prosopagnosia in a young man aged 19 years and 10 months, followed until age 21 years and 6 months, is described. He also exhibited petit-mal seizures since the age of 18 years, these two pathological manifestations being chronologically independent. Clinically, were noted a total absence of hetero-prosopagnosia, color-agnosing agnosia for objects or body scheme disorders. The ophtalmologic examination was totally normal. The psychologie study was performed with the aid of the psychodiagnostic tests of Rorschach, Fuchs, Kataguchi and with the "Symbol-Test" of Roemer, and the result obtained, as well as their psychodynamic meanings are detailed. Disappearance, at the age of 21 years and 6 months, of the auto-prosopagnosia and rarefaction of the petit-mal seizures. In a brief survey of the literature, the author underlines the indisputable scarcity of the isolated and paroxystic forms of auto-prosopagnosia as well as their association with epilepsy.

Adult↗