Cases reported "Prosopagnosia"

Filter by keywords:

Retrieving documents. Please wait...

1/48. Naming people ignoring semantics in a patient with left frontal damage.

    Studies about proper name anomia generally assume that persons' names are harder to recall than other semantic information one knows about them and that name retrieval is not possible without biographical knowledge. We describe a patient, SB, who, after a left frontal haemorrhage, was unable to recall any biographical information about people she could name. Moreover, she had a normal score in an Object Picture Naming Test, but gave confabulatory answers in a Semantic Questionnaire involving the same items. The role of frontal function in producing this pattern of impairment is discussed, together with the possible existence of a direct route from visual perception to proper name retrieval. ( info)

2/48. Loss of topographic memory and prosopagnosia during migraine aura.

    We report the case of a 28-year-old woman with a past history of acephalalgic migraine. She had a complex migraine aura with left-sided scintillating scotomas, hemianopia, left-sided paresthesias, a loss of topographic and procedural memory, and prosopagnosia. The rarity of right hemisphere cognitive dysfunction during the aura, its diagnostic difficulties, and differential diagnosis are discussed. ( info)

3/48. Developmental prosopagnosia with normal configural processing.

    The configural processing hypothesis proposes that prosopagnosia results from a domain-general impairment in configural processing, and so predicted that all prosopagnosics would have impaired configural processing. In order to test this prediction, tests of face recognition and configural processing were presented to a developmental prosopagnosic. He was severely impaired in face recognition, but his normal performance on three tests of configural processing disconfirmed the configural processing hypothesis. Additional tests of low-level vision and object recognition found no evidence of impairments with material other than faces. The pattern of spared and impaired face recognition indicates that this case of developmental prosopagnosia is caused by a domain-specific inability to match novel views of faces with previously derived representations. ( info)

4/48. A case of prosopagnosia following moderate closed head injury with left hemisphere focal lesion.

    This study describes a left handed woman with prosopagnosia following traumatic brain injury with a focal lesion confined to the left-posterior hemisphere. Few cases of prosopagnosia following unilateral left hemisphere lesions have previously been reported in the literature. Corrected visual acuity was 20/70 (binocular), color vision was intact on screening, and shape detection was borderline. Impairments in higher order visual perception were evident to varying degrees on nonfacial tasks. Matching of unfamiliar faces was very slow but accurate. A marked impairment in the ability to recognize familiar faces and learn new face-name associations was evident on experimental tasks relative to the performance of healthy control subjects. In contrast, identification of characteristics of faces (gender, age) and identification and matching of facial expressions were relatively preserved. We discuss the cognitive processing stages that appear to be disrupted using Bruce and Young's (1986) model of facial recognition and perception as a framework. ( info)

5/48. Paradoxical configuration effects for faces and objects in prosopagnosia.

    Selective impairment in recognition of faces (prosopagnosia) has been advanced as an argument for a brain module dedicated to face processing and focusing on the specific configural properties of faces. Loss of the inversion effect supposedly strengthened the argument ([10]: de Gelder B, Bachoud-Levi AC, Degos JD. Inversion superiority in visual agnosia may be common to a variety of orientation polarised objects besides faces. Vision research, 1998;38:2855-61; [20]: Farah MJ, Wilson K, Drain H, Tanaka J. The inverted face inversion effect in prosopagnosia: Evidence for mandatory, face-specific perceptual mechanisms. Vision research 1995b;35:2089-93). The present study of prosopagnosic patient LH reports that he has lost the normal pattern of superior performance with upright faces and objects and shows instead paradoxical inversion effect for faces but also for objects. Experiment 2 investigated whether LH's use of features based route for processing upright objects would be hindered by the whole-based encoding when processing upright objects. The data show the same context effect for objects as was found for faces. Therefore the inversion effect does not present decisive evidence for the existence of a face module. Moreover, the importance of configuration-based recognition known to be crucial for face processing, must also be taken seriously for object recognition. ( info)

6/48. Effect of training frequency on face-name recall by adults with traumatic brain injury.

    Many TBI survivors have difficulty recalling the names of people with whom they frequently interact. Researchers have established that mnemonics and visual imagery strategies are often effective in facilitating encoding and recall of such information; however, no research exists pertaining to the frequency that such training should occur. The purpose of this study was to assess the relative effectiveness of three frequencies of intervention sessions--once per day, two times per week, and five times per day--on TBI survivors' ability to recall face-name associations. Results showed that sessions held daily and twice a week were more effective than sessions held five times per day. Mnemonics and visual imagery strategies were effective for four of the seven participants, regardless of frequency of intervention sessions. Implications for treatment and future research are discussed. ( info)

7/48. Covert processing of faces in prosopagnosia is restricted to facial expressions: evidence from cross-modal bias.

    We present a single case study of a brain-damaged patient, AD, suffering from visual face and object agnosia, with impaired visual perception and preserved mental imagery. She is severely impaired in all aspects of overt recognition of faces as well as in covert recognition of familiar faces. She shows a complete loss of processing facial expressions in recognition as well as in matching tasks. Nevertheless, when presented with a task where face and voice expressions were presented concurrently, there was a clear impact of face expressions on her ratings of the voice. The cross-modal paradigm used here and validated previously with normal subjects (de Gelder & Vroomen, 1995, 2000), appears as a useful tool in investigating spared covert face processing in a neuropsychological perspective, especially with prosopagnosic patients. These findings are discussed against the background of different models of the covert recognition of face expressions. ( info)

8/48. Developmental prosopagnosia: should it be taken at face value?

    This study presents a rare case of developmental prosopagnosia. Structural magnetic resonance imaging (MRI) revealed no overt brain abnormalities. EP's basic visual skills and visual memory were intact, as was his ability to judge age, sex and expression from faces, identify facial parts, and make face/non-face decisions. EP was impaired at recognizing famous and very familiar faces and describing visual images of famous faces. He also displayed an anterograde memory impairment for recently studied faces, and performed poorly on tests of unfamiliar face matching, most notably for chimeric faces. It is suggested that EP may be deficient at encoding configural representations of faces. EP appears to have a "pure" (i.e. specific to faces) prosopagnosia, as he shows normal object recognition from unusual viewpoints, good gestalt completion for objects, but not for faces, normal visual imagery for objects but not for faces, a disruption of the inversion effect for faces but not for houses, and performs within the normal range on tests of within-category discriminations, even with unique exemplars of object categories such as famous buildings. ( info)

9/48. Severe developmental prosopagnosia in a child with superior intellect.

    Developmental prosopagnosia, a lifelong inability to learn and recognize familiar faces, has rarely been reported, and there are even fewer cases that have been studied during childhood. Of the cases studied during childhood, significant "apperceptive" features to the face recognition defect have been noted. We had an opportunity to conduct extensive standard and experimental neuropsychological, psychophysiological, and neuroanatomical studies in a five-year-old child with severe developmental prosopagnosia. The subject was intellectually gifted (FSIQ = 130), but had a marked discrepancy between verbal and nonverbal abilities (VIQ = 140, PIQ = 110). Although some visual perceptual weaknesses were apparent, the subject's face recognition defect was found to cnform most closely to the "associative" type, and he did not have visual recognition deficits for any categories of nonunique entities. A novel finding was that the child's covert recognition of familiar faces based on an autonomic index was normal, suggesting that as in some adult-onset cases, the brain is capable of acquiring some information about familiar faces, even without conscious recognition. The child also had normal judgments of facial emotional expressions. Our report extends the understanding of the neuropsychological features of developmental prosopagnosia, and may help narrow the search for neuroanatomical correlates of this condition, which have yet to be identified. ( info)

10/48. prosopagnosia as a deficit in encoding curved surface.

    RP is a case of "developmental" prosopagnosia who, according to brain-imaging segmentation data, shows reduction in volume of a limited set of structures of the right hemisphere. RP is as accurate as control subjects in tasks requiring the perception of nonface objects (e.g., matching subordinate labels to exemplars, naming two-tone images), with the exception of one perceptual task: The matching of different perspectives of amoebae-like stimuli (i.e., volumes made of a single smooth surface). In terms of speed ("efficiency") of responses, RP's performance falls clearly outside the normal limits also in other tasks that include "natural" but nonface stimuli (i.e., animals, artia facts). Specifically, RP is slow in perceptual judgments made at very low (subordinate) levels of semantic categorization and for objects and artifacts whose geometry present much curved features and surface information. We conclude from these analyses that prosopagnosia can be the result of a deficit in the representation of basic geometric volumes made of curved surface. In turn, this points to the importance (necessity) for the normal visual system of such curved and volumetric information in the identification of human faces. ( info)
| Next ->

Leave a message about 'prosopagnosia'

We do not evaluate or guarantee the accuracy of any content in this site. Click here for the full disclaimer.