1/84. Visual environmental rotation: a novel disorder of visiospatial integration.A 70-year-old man experienced an unusual disorder of visual perception after undergoing a ventriculoperitoneal shunt for normal-pressure hydrocephalus. The disorder was characterized by transient episodes of 90 degrees rotation of the visual environment, rather than the retinotopic visual field. This phenomenon is different from standard visual allesthesia and may have been caused by disordered integration of vestibular and visual inputs to the posterior parietal cortex or perseveration of a pre-existing environmental memory trace.- - - - - - - - - - ranking = 1keywords = perception (Clic here for more details about this article) |
2/84. Impairment of depth perception in multiple sclerosis is improved by treatment with AC pulsed electromagnetic fields.multiple sclerosis (MS) is associated with postural instability and an increased risk of falling which is facilitated by a variety of factors including diminished visual acuity, diplopia, ataxia, apraxia of gait, and peripheral neuropathy. Deficient binocular depth perception may also contribute to a higher incidence of postural instability and falling in these patients who, for example, find it an extremely difficult task to walk on uneven ground, over curbs, or up and down steps. I report a 51 year old woman with secondary progressive MS who experienced difficulties with binocular depth perception resulting in frequent falls and injuries. Deficient depth perception was demonstrated also on spontaneous drawing of a cube. Following a series of transcranial treatments with AC pulsed electromagnetic fields (EMFs) of 7,5 picotesla flux density, the patient experienced a major improvement in depth perception which was evident particularly on ascending and descending stairs. These clinical changes were associated with an improvement in spatial organization and depth perception on drawing a cube. These findings suggest that in MS impairment of depth perception, which is encoded in the primary visual cortex (area 17) and visual association cortex (areas 18 and 19), may be improved by administration of AC pulsed EMFs of picotesla flux density. The primary visual cortex is densely innervated by serotonergic neurons which modulate visual information processing. Cerebral serotonin concentrations are diminished in MS patients and at least some aspects of deficient depth perception in MS may be related to dysfunction of serotonergic transmission in the primary visual cortex. It is suggested that transcranial AC pulsed applications of EMFs improve depth perception partly by augmenting serotonergic transmission in the visual cortex.- - - - - - - - - - ranking = 12keywords = perception (Clic here for more details about this article) |
3/84. Akinetopsia from nefazodone toxicity.PURPOSE: To investigate two cases of selective impairment of motion perception (akinetopsia) induced by toxicity from the antidepressant nefazodone, a new drug that blocks serotonin reuptake and antagonizes 5-HT2 receptors. methods: case reports. RESULTS: A 47-year-old man receiving nefazodone (Serzone; Bristol-Meyers Squibb, new york, N.Y.) (100 mg twice daily), reported a bizarre derangement of motion perception. Moving objects were followed by a trail of multiple "freeze-frame" images, which dissipated promptly when motion ceased. A 48-year-old woman receiving nefazodone (400 mg daily at bedtime) reported a similar phenomenon, with visual trails following moving objects. In both patients, vision returned to normal after the dosage of nefazodone was reduced or eliminated. CONCLUSIONS: Nefazodone toxicity can result in akinetopsia, characterized by the inability to perceive motion in a normal, smooth fashion; persistence of multiple, strobelike images; and visual trails behind moving objects. In this rare syndrome, stationary elements are perceived normally, indicating that nefazodone causes selective impairment of pathways involved in motion processing in the visual system.- - - - - - - - - - ranking = 2keywords = perception (Clic here for more details about this article) |
4/84. blindness to form from motion despite intact static form perception and motion detection.We studied the motion perception, including form and meaning generated by motion, in a hemianopic patient who also had visual perceptual impairments in her seeing hemifield as a result of a lesion in ventral extrastriate cortex. She was unable to recognise 2- or 3-dimensional forms, and even borders, generated by motion alone, failed to recognise mimed actions or the Johannson 'biological motion' display, and ceased to recognise people well-known to her when they moved. Her performance with static displays, although impaired, could not explain her inability to perceive shape or derive meaning from moving displays. Unlike a motion-blind patient, she can still see and describe the motion, with the exception of second-order motion, but not what it creates or represents.- - - - - - - - - - ranking = 5keywords = perception (Clic here for more details about this article) |
5/84. Relation of impairment to everyday competence in visual disorientation syndrome: evidence from a single case study.OBJECTIVE: To determine the relation of neurology and neuropsychology to everyday competence. DESIGN: The association of these three domains was investigated using a single case multiple baseline design with two phases. Phase A comprised 6 weeks that coincided with an inpatient admission. Phase B comprised 3 months spent at home. A battery of visual spatial tests was completed every fortnight during the A phase and at the end of the B phase. Two new tests of relevant neurologic function with control data were developed and used weekly during the A phase and at the end of the B phase. The first test recorded the speed, accuracy, and efficiency of her walking, and the second test recorded her depth perception. SETTING: Tertiary care center. PARTICIPANT: A 35-year-old woman who suffered a venous sinus thrombosis with visual disorientation syndrome. RESULTS: During Phase A, she achieved significant functional gains in mobility, dressing, bathing, and domestic tasks, in the context of unchanging psychometric test scores and static relevant neurologic function. During Phase B, she achieved few functional gains, despite improvements in neurologic status, demonstrated by depth perception. CONCLUSIONS: Everyday function can progress without improvement in neurologic and cognitive status.- - - - - - - - - - ranking = 2keywords = perception (Clic here for more details about this article) |
6/84. A transient deficit of motion perception in human.We studied the motion perception abilities in a young adult, SF, who had her right occipito-temporal cortices resected to treat epilepsy. Following resection, SF showed transient deficits of both first- and second-order motion perception that recovered to normal within weeks. Previous human studies have shown either first- or second n order motion deficits that have lasted months or years after cerebral damage. SF also showed a transient defect in processing of shape-from-motion with normal perception of shape from non-motion cues. Furthermore, she showed greatly increased reaction times for a mental rotation task, but not for a lexical decision task. The nature and quick recovery of the deficits in SF resembles the transient motion perception deficit observed in monkey following ibotenic acid lesions, and provides additional evidence that humans possess specialized cortical areas subserving similar motion perception functions.- - - - - - - - - - ranking = 9keywords = perception (Clic here for more details about this article) |
7/84. 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 = 2.0340393422067keywords = perception, speech (Clic here for more details about this article) |
8/84. Cognitive dysfunction of right hemisphere-like Todd's paralysis after status epilepticus: a case report.We describe a case with symptoms of transient diffuse right hemisphere dysfunction (hemispatial neglect, dyscalculia, and disturbance of both spatial construction and visuospatial perception) occurring after status epilepticus. The clinical picture of this case suggested to us that these features could be understood as a variant of Todd's paralysis.- - - - - - - - - - ranking = 1keywords = perception (Clic here for more details about this article) |
9/84. Establishing joint visual attention and pointing in autistic children with no functional language.Joint visual attention is defined as looking where someone else is looking. The purpose of this study was to examine the conditions for establishing joint visual attention in autistic children who have no functional speech. An experimenter, sitting facing the child, looked at one of six pictures near the child. Analysis showed that joint visual attention to stimuli behind the child and therefore outside of the visual field occurred at a higher rate when the visual angle between the stimuli was about 60 degrees. Spontaneous pointing at the target object increased with training which included feedback and physical guidance. These results are discussed in terms of the effects of environmental variables and perceptual mechanisms on the emergence of joint visual attention in autistic children. The possibility of using an adult's social cues and expanding the child's visual field as a remedial procedure is also addressed.- - - - - - - - - - ranking = 0.017019671103366keywords = speech (Clic here for more details about this article) |
10/84. Impaired short temporal interval discrimination in a dyslexic adult.The ability to discriminate short temporal intervals was examined in a dyslexic adult (E.C.) and six matched controls. Listeners had to decide whether the second interval was shorter or longer than a standard (target) interval. Each interval was defined as the silent duration between two successive brief tones. Eight target intervals were used, ranging from 100 to 1,200 ms in duration. At each target interval, the differential threshold (DL) for duration was assessed, with the use of an adaptive psychophysical procedure. The results show that E.C.'s differential threshold values were much larger than those of controls. Moreover, the slope estimates covering the duration range from 100 to 800 ms indicated that in comparison to controls, E.C.'s differential threshold increased dramatically as the target duration increased. Thus her timing impairment becomes more pronounced with increasing duration. This timing deficit is consistent with other studies that have found temporal processing deficits associated with dyslexia.- - - - - - - - - - ranking = 3.0591316699541keywords = discrimination (Clic here for more details about this article) |
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