1/60. Tactile morphagnosia secondary to spatial deficits.A 73-year old man showed visual and tactile agnosia following bilateral haemorrhagic stroke. Tactile agnosia was present in both hands, as shown by his impaired recognition of objects, geometrical shapes, letters and nonsense shapes. Basic somatosensory functions and the appreciation of substance qualities (hylognosis) were preserved. The patient's inability to identify the stimulus shape (morphagnosia) was associated with a striking impairment in detecting the orientation of a line or a rod in two- and three-dimensional space. This spatial deficit was thought to underlie morphagnosia, since in the tactile modality form recognition is built upon the integration of the successive changes of orientation in space made by the hand as it explores the stimulus. Indirect support for this hypothesis was provided by the location of the lesions, which could not account for the severe impairment of both hands. Only those located in the right hemisphere encroached upon the posterior parietal cortex, which is the region assumed to be specialised in shape recognition. The left hemisphere damage spared the corresponding area and could not, therefore, be held responsible for the right hand tactile agnosia. We submit that tactile agnosia can result from the disruption of two discrete mechanisms and has different features. It may arise from a parietal lesion damaging the high level processing of somatosensory information that culminates in the structured description of the object. In this case, tactile recognition is impaired in the hand contralateral to the side of the lesion. Alternatively, it may be caused by a profound derangement of spatial skills, particularly those involved in detecting the orientation in space of lines, segments and complex patterns. This deficit results in morphagnosia, which affects both hands to the same degree.- - - - - - - - - - ranking = 1keywords = agnosia, recognition (Clic here for more details about this article) |
2/60. A category-specific deficit of spatial representation: the case of autotopagnosia.Following a vascular lesion in the parietal cortex of the language dominant hemisphere (right in one case), two patients showed a striking dissociation between spared naming, recognition and use of their body parts and an inability in localising on verbal command the same body parts on themselves and on a mannequin (Autotopagnosia, AT). The patients were submitted to a modified version of Reed and Farah Test (1995), a test that taps the ability to encode changes of body position as opposed to changes of position of objects. Their performance differed from normal controls, showing a specific deficit in encoding body position.It is suggested that AT could be the consequence of a lesion in a specific neural circuit, located in the language dominant hemisphere, whose function is to encode the body position for both oneself and others.- - - - - - - - - - ranking = 0.45448447417824keywords = agnosia, recognition (Clic here for more details about this article) |
3/60. Faces call for attention: evidence from patients with visual extinction.Three patients with left spatial neglect and visual extinction from right brain damage were studied to determine whether faces are privileged in summoning attention. In a first experiment, either a face, a name, or a meaningless shape were briefly presented in the right, left or both visual hemifields. On bilateral trials, all patients extinguished a left-side face much less often than a left-side name or a left-side shape. Conversely, they extinguished a left-side shape more often when it was accompanied by a right-side face rather than a right-side name. In a second experiment, either a face or a scrambled face could appear in the right, left or both hemifields. Again, on bilateral trials, a left-side face was less likely to be missed than a scrambled one. These results suggest an advantage of faces in capturing attention and overcoming extinction, which may be related to their special biological and social value, or to the very efficient and automatic operation of specific perceptual processses that extract facial organization in extrastriate visual areas. These findings also demonstrate that the distribution of spatial attention and extinction can be modulated by the relevance of visual stimuli. This implies that substantial analysis and categorization may take place in the visual system before information from the contralesional field is selected for, or excluded from, attentive vision.- - - - - - - - - - ranking = 0.00054666746747534keywords = face, facial (Clic here for more details about this article) |
4/60. Visual implicit memory deficit and developmental surface dyslexia: a case of early occipital damage.This study reports the case of EBON, a fifteen-year-old right-handed female Swedish student, who suffered an early medial/dorsal occipital brain lesion and showed a clearly defined pattern of developmental surface dyslexia. EBON and 17 controls were examined with within and cross-modality (visual and auditory) word stem completion tasks together with tasks requiring free-recall and recognition for visually and auditory presented words. Compared to age-matched controls, EBON was found to show a significant deficit of visual priming following visual presentation, and a deficit approaching significance following auditory presentation. Explicit memory and visual and spatial abilities were not significantly different from controls. Therefore, EBON represents the first childhood case establishing the role of occipital regions in visual priming, as well as illustrating a profile of surface reading difficulty as a developmental consequence of this locus of lesion.- - - - - - - - - - ranking = 0.0004782269740766keywords = recognition, face (Clic here for more details about this article) |
5/60. Corticobasal ganglionic degeneration with Balint's syndrome.Corticobasal ganglionic degeneration (CBGD) is a neurodegenerative dementia characterized by asymmetric parkinsonism, ideomotor apraxia, myoclonus, dystonia, and the alien hand syndrome. This report describes a patient with CBGD who developed Balint's syndrome with simultanagnosia, oculomotor apraxia, and optic ataxia.- - - - - - - - - - ranking = 0.090881988523663keywords = agnosia (Clic here for more details about this article) |
6/60. Unilateral spatial neglect associated with chronic subdural haematoma: a case report.A 69-year-old right-handed man who exhibited unilateral spatial neglect in association with a chronic subdural haematoma, presented with mild left arm and leg weakness first noted 4 weeks prior to admission. neurologic examination on admission revealed a mild left hemiparesis, including the face. Neuropsychologic examination revealed left unilateral spatial neglect, but no language disturbance. Minimal support was necessary to maintain activities of daily living. Computed tomography revealed a large right temporoparietal, extraaxial hypodense fluid collection containing scattered hypodense foci. The haematoma was evacuated via a right parietal burr hole. Following surgery, the patient dramatically improved neurologically and neuropsychologically, as well as in independent performance of daily activities. It is suggested that the improvement in ADL provides a behavioural correlate of improvement in the latter, represented a behavioural correlate of improved cerebral function, and that either direct compression by the chronic subdural haematoma or an interhemispheric pressure difference had caused unilateral spatial neglect. Such neglect is an unusual consequence of chronic subdural haematoma.- - - - - - - - - - ranking = 6.7282569024848E-5keywords = face (Clic here for more details about this article) |
7/60. Disordered recognition of facial identity and emotions in three Asperger type autists.In this report we aim to explore severe deficits in facial affect recognition in three boys all of whom meet the criteria of Asperger's syndrome (AS), as well as overt prosopagnosia in one (B) and covert prosopagnosia in the remaining two (C and D). Subject B, with a familially-based talent of being highly gifted in physics and mathematics, showed no interest in people, a quasi complete lack of comprehension of emotions, and very poor emotional reactivity. The marked neuropsychological deficits were a moderate prosopagnosia and severely disordered recognition of facial emotions, gender and age. Expressive facial emotion, whole body psychomotor expression and speech prosody were quasi absent as well. In all three boys these facial processing deficits were more or less isolated, and general visuospatial functions, attention, formal language and scholastic performances were normal or even highly developed with the exception of deficient gestalt perception in B. We consider the deficient facial emotion perception as an important pathogenetic symptom for the autistic behaviour in the three boys. prosopagnosia, the absent facial and bodily expression, and speech prosody were important but varying co-morbid disorders. The total clinical picture of non-verbal disordered communication is a complex of predominantly bilateral and/or right hemisphere cortical deficits. Moreover, in B, insensitivity to pain, smells, noises and internal bodily feelings suggested a more general emotional anaesthesia and/or a deficient means of expression. It is possible that a limbic component might be involved, thus making affective appreciation also deficient.- - - - - - - - - - ranking = 0.49654714385732keywords = agnosia, prosopagnosia, recognition, facial (Clic here for more details about this article) |
8/60. prosopagnosia: a case study involving problems in processing configural information.An ongoing issue in face recognition research is whether holistic face processing relies on the segregation of local discrete facial parts. Evidence in favor of the holistic-plus-parts view stems from a recent study reported by Arguin and Saumier (1999), who show that the priming effects of individual facial parts (i.e., eyes, nose, mouth, orcontour) depends on the presence of configural information and that the magnitude of priming augments as the number of facial parts serving as primes increase. The present study demonstrates that these global processing effects are absent in a prosopagnosic patient (A.R.), who shows no priming from single face parts and a linear increase in the magnitude of priming as a function of the number of parts presented. These findings indicate that A.R. is incapable of integrating individual facial parts into a global facial configuration ant that this is likely at the root of her prosopagnosia.- - - - - - - - - - ranking = 0.49889100021181keywords = agnosia, prosopagnosia, recognition, face, facial (Clic here for more details about this article) |
9/60. Two eyes make a pair: facial organization and perceptual learning reduce visual extinction.We examined a patient with left spatial neglect and visual extinction due to right parietal damage in tasks where identical stimuli were presented before and after they were primed so as to be perceived as the eyes of schematic faces. In a first block, we presented alphanumeric stimuli ( , o, T, 6) on the right, left, or both sides of fixation on a blank background, and established that the patient could perceive unilateral stimuli on either side but extinguished most of the left-sided ones in the bilateral trials. In a second block, some of these stimuli ( , o) were presented again, but now in the position of eyes within the context of an oval frame which created the impression of a schematic face. Other stimuli (T, 6) were presented as previously on a blank background for an equal number of trials. In the third critical block, all stimuli were presented once again on a blank background, as in the first block. Now the patient extinguished very few of those left-sided stimuli primed to be seen as a pair of eyes in face configuration ( , o), but still extinguished most of the other stimuli (T, 6). A second control experiment showed no effect of repeatedly exposing stimuli in a common region of space defined by meaningless shape boundaries. These results suggest that facial organization can group eye features before the level where attentional selection or extinction occurs, and that such grouping may be influenced by rapid perceptual learning.- - - - - - - - - - ranking = 0.00024388228345732keywords = face, facial (Clic here for more details about this article) |
10/60. Perceived gaze direction in faces and spatial attention: a study in patients with parietal damage and unilateral neglect.Perceived gaze in faces is an important social signal that may influence orienting of attention in normal observers. Would such effects of gaze still occur in patients with right parietal damage and left neglect who usually fail to attend to contralesional space? Two experiments tested for effects of perceived gaze on visual extinction. face or shape stimuli were presented in the right, left, or both hemifields, with faces looking either straight ahead or toward the opposite field. On bilateral trials, patients extinguished a left shape much less often when a concurrent right face looked leftward rather than straight ahead. This occurred, even though gaze was not relevant to the task and processing of facial signals implied attention to a competing ipsilesional stimulus. By contrast, rightward gaze in faces presented on the left side had no effect on extinction, suggesting that gaze cues are not extracted without attention. Two other experiments examined effects of perceived gaze on the detection of peripheral targets. Targets appeared at one of four possible locations to the right or left of a central face looking either toward the target location, another location on the same side, the opposite side, or straight ahead. face and gaze were not relevant to the task and not predictive of target location. patients responded faster when the face looked toward the target on both the contralesional and ipsilesional sides. In contralesional space, gaze allowed shifting of attention in a specific quadrant direction, but only to the first target along the scan path when there were different possible locations on the same side. By contrast, in intact ipsilesional space, attention was selectively directed to one among different eccentric locations. Control experiments showed that symbolic arrow cues did not produce similar effects. These results indicate that even though parietal damage causes spatial neglect and impairs the representation of location on the contralesional side, perceived gaze in faces can still trigger automatic shifts of attention in the contralesional direction, suggesting the existence of specific and anatomically distinct attentional mechanisms.- - - - - - - - - - ranking = 0.00074851517454988keywords = face, facial (Clic here for more details about this article) |
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