11/46. Exacerbation of psychosis by misinterpretation of physical symptoms.Impaired processing of perceptual information is often a prominent aspect of psychotic disorders. Physical symptoms such as pain or discomfort may be either incorrectly perceived or misinterpreted by psychotic patients. Presented here is a series of cases in which somatic symptoms occurred in psychotic patients and worsened their psychotic states but only later were recognized as physical problems. Psychotic patients may be unable to comprehend or describe their physical symptoms adequately. Physical disorders of psychotic patients may be overlooked if clinicians are not vigilant and thorough in assessing the patients' complaints, especially if such complaints sound delusional or bizarre.- - - - - - - - - - ranking = 1keywords = information (Clic here for more details about this article) |
12/46. Can spatial and temporal motion integration compensate for deficits in local motion mechanisms?We studied the motion perception of a patient, AMG, who had a lesion in the left occipital lobe centered on visual areas V3 and V3A, with involvement of underlying white matter. As shown by a variety of psychophysical tests involving her perception of motion, the patient was impaired at motion discriminations that involved the detection of small displacements of random-dot displays, including local speed discrimination. However, she was unimpaired on tests that required spatial and temporal integration of moving displays, such as motion coherence. The results indicate that she had a specific impairment of the computation of local but not global motion and that she could not integrate motion information across different spatial scales. Such a specific impairment has not been reported before.- - - - - - - - - - ranking = 1keywords = information (Clic here for more details about this article) |
13/46. tinnitus in childhood.All of 1,420 children seen for clarification of a hearing disorder or to follow up for known difficulty in hearing were questioned as to whether they experienced tinnitus. The interview was carried out after a hearing test was conducted, which was based on play audiometry or normal pure-tone threshold audiometry, depending on the age of the child. When being interviewed, 102 children reported that tinnitus had appeared or was still present. Seventy-five children (73.5%) demonstrated difficulty in hearing in one or both ears, whereas 27 children (26.5%) had normal hearing in both ears. The most frequently obtained information (29.4%) was the progression of an existing hearing loss. meningitis is an important cause of hearing loss and of tinnitus and could be identified in 20% of our patients. We also considered as a cause of tinnitus skull or brain trauma, acute hearing loss, and stapes surgery. However, the mechanisms of tinnitus development were not immediately clear in a large proportion of the children studied: Problems included central sensory perception (14.7%) and emotional factors (11.8%). No additional information that might lead to an understanding of the hearing loss was available for 14.7% of the patients studied. tinnitus is a frequent symptom in childhood and, because children seldom complain about their tinnitus, such hearing problems that they report must always be taken seriously. The diagnosis should exclude metabolic disturbances, possible damage to the sensory level of the central nervous system, and circulatory disturbances. In addition, the physician should always consider emotional problems and disturbances of perception.- - - - - - - - - - ranking = 2keywords = information (Clic here for more details about this article) |
14/46. Crossed Wernicke's aphasia: a case report.Crossed aphasia is a phenomenon in which an individual sustains a lesion in the right hemisphere (typically non-language dominant), but who exhibits an aphasic syndrome. The authors present a case study of an individual with crossed aphasia (CA) in an attempt to provide anecdotal information for four questions posed by : (a). Is CA a reversal of the normal cerebral hemisphere pattern of language function? (b). Does the presence of aphasia following a right cerebral hemisphere lesion indicate that typical right hemisphere functions (e.g., visual perception) are intact? (c). How may the aphasia's presentation differ from typical left hemisphere aphasias? And (d). is the pattern of improvement following CA similar to that of typical left hemisphere aphasias? We longitudinally examined the communicative-cognitive performance of an adult man with crossed aphasia of the Wernicke's type following a cerebrovascular accident. A 21-week follow-up evaluation indicated improvements in his language functioning from our initial evaluation, but he continued to exhibit a classic, moderately severe Wernicke's aphasia.- - - - - - - - - - ranking = 1keywords = information (Clic here for more details about this article) |
15/46. Unilateral spatial neglect following right inferior parietal cortectomy.research in brain-damaged patients has suggested that the right hemisphere plays a role in unilateral spatial neglect (USN), but provides only limited information for pinpointing the intraparietal localization of the lesions associated with this syndrome. We report a case of unilateral neglect in a patient who underwent a right inferior parietal cortectomy for refractory epilepsy without any macroscopic lesion. We describe the evolution of the neuropsychological disturbances observed at 3 and 24 months after cortectomy. This case illustrates the role played by the inferior parietal lobe and, particularly, the parietal opercule in USN syndrome, and provides strong "experimental" evidence of the special role played by the inferior parietal lobule in the perception processes related to spatial attention.- - - - - - - - - - ranking = 1keywords = information (Clic here for more details about this article) |
16/46. Geographic information has to be spatialized to be neglected: a representational neglect case.A patient with unilateral neglect had to evoke mentally the map of france in two different conditions. In the first condition, he was asked to build an iconic representation of the map of france and to list all the towns that he could 'see' on this mental image within two minutes. In the second condition, he had to remember and name as many French towns as possible within two minutes, without being instructed to form a mental image. Left representational neglect was observed in the first condition only, i.e., when an iconic representation was required. These findings, which were replicated four months later, suggest a dual mode of coding, retrieval, or both, of geographic information and show that, although topographic, geographic data has to be spatialized to be neglected.- - - - - - - - - - ranking = 5keywords = information (Clic here for more details about this article) |
17/46. Clinical application of the multifocal visual evoked potential.BACKGROUND: Measures of visual function thresholds such as visual acuity and visual fields are generally dependent on subjective responses and assume maintenance of fixation, attention and motivation. In the young, elderly, cognitively impaired or malingering populations, such measures may be inaccurate or difficult to obtain. The Visual Evoked Response Imaging System (VERIS) has been claimed to give more objective topographic recordings of retinal and cortical function. This paper aims to explore the adequacy of this technique in four unusual, unrelated, clinically difficult cases. methods: Multifocal visual evoked potentials (mfVEPs) recorded on the VERIS System 3.01 are used to assess visual function in four cases with contradictory clinical findings or unreliable subjective responses. RESULTS: Patient 1 had sustained a head injury and had normal ocular and pupil examination but light perception in the right eye and 6/5 acuity in the left. Multifocal VEPs showed a marked depression of the right visual field with little macular response. Patient 2 had sustained a head injury, had a left field hemianopia, possible macular sparing and loss of much of the right field, reduced but variable visual acuities, good near vision and normal ocular fundi. Multifocal VEPs showed a severe depression in both visual fields (L more than R) with little macular response. Patient 3 had a left optic nerve meningioma and experienced great difficulty with visual field assessment. mfVEPs showed a bilateral depression in the superior field particularly the left field, with a larger deficit in the left eye. Patient 4 had unexplained visual acuity and peripheral field deficits. mfVEP results were inconclusive in this case. DISCUSSION: Where there is difficulty performing traditional techniques or conflicting clinical findings, mfVEPs may provide additional objective information to aid in the assessment of patients.- - - - - - - - - - ranking = 1keywords = information (Clic here for more details about this article) |
18/46. Spatial representations and multiple-visual-systems hypotheses: evidence from a developmental deficit in visual location and orientation processing.AH, a young, well-educated woman, has a developmental deficit in processing visual location and orientation information. Her deficit manifests itself in a wide range of visual tasks, including visually-guided reaching, copying pictures and words, and responding verbally to the location or orientation of visual stimuli; however, her performance in non-visual localization tasks is intact. AH's visual location and orientation errors are systematic left-right or up-down reflections (e.g., reaching to the far right for an object on the far left). More specifically, the errors involve reflection across the point where AH's attention is focused, regardless of where her eyes are fixated. These results imply that at some level(s) of the visual system, locations and orientations of visual stimuli are represented in a spatial coordinate system with an origin defined by the focus of attention. In these attention-centered representations location is specified in terms of distance and direction of displacement from the attentional focus along horizontal and vertical reference axes. AH's errors, I argue, result from misrepresentation of displacement direction (e.g., left rather than right, down rather than up) along a reference axis. Several visual variables dramatically affected AH's performance in visual location and orientation tasks: She was much more accurate for stimuli that were brief, moving, flickering, low in contrast, or high in eccentricity, than for those that were long in duration, stationary, continuous, high in contrast, and low in eccentricity. These results suggest that location and orientation are computed in each of two visual subsystems, which I call transient and sustained, and that AH's deficit affects only the sustained subsystem. I argue that AH's performance poses challenges to multiple-visual-subsystems hypotheses proposed by Ungerleider and Mishkin (1982) and by Milner and Goodale (1995).- - - - - - - - - - ranking = 1keywords = information (Clic here for more details about this article) |
19/46. 2D but not 3D: pictorial-depth deficits in a case of visual agnosia.patients with visual agnosia exhibit acquired impairments in visual object recognition, that may or may not involve deficits in low-level perceptual abilities. Here we report a case (patient DM) who after head injury presented with object-recognition deficits. He still appears able to extract 2D information from the visual world in a relatively intact manner; but his ability to extract pictorial information about 3D object-structure is greatly compromised. His copying of line drawings is relatively good, and he is accurate and shows apparently normal mental rotation when matching or judging objects tilted in the picture-plane. But he performs poorly on a variety of tasks requiring 3D representations to be derived from 2D stimuli, including: performing mental rotation in depth, rather than in the picture-plane; judging the relative depth of two regions depicted in line-drawings of objects; and deciding whether a line-drawing represents an object that is 'impossible' in 3D. Interestingly, DM failed to show several visual illusions experienced by normals (Muller-Lyer and Ponzo), that some authors have attributed to pictorial depth cues. Taken together, these findings indicate a deficit in achieving 3D intepretations of objects from 2D pictorial cues, that may contribute to object-recognition problems in agnosia.- - - - - - - - - - ranking = 2keywords = information (Clic here for more details about this article) |
20/46. Spatial transpositions across tasks and response modalities: exploring representational allochiria.We describe a neglect patient who showed systematic transpositions of left-sided items onto the right side in clock drawing. When the patient had to write single hours on blank clock dials he again showed allochiria, while he copied single spatial locations without transpositions. The patient also showed a variable number of spatial transpositions on imaginal tasks with well known and novel material acquired through visual modality and on controlled constructional tasks, independently from response modality (verbal, graphic or motor). From this basis, we argued that spatial transpositions may derive from an impairment of the mental representation of space. Moreover, we speculated that such errors may result from cognitive conflict between different sources of information.- - - - - - - - - - ranking = 1keywords = information (Clic here for more details about this article) |
| <- Previous || Next -> |