Search results for "Visual Perception"
showing 10 items of 387 documents
Fixation suppression of optokinetic nystagmus modulates cortical visual-vestibular interaction.
2005
Water activation positron emission tomography and statistical group analysis were used to evaluate differences in activation-deactivation patterns during small-field visual motion stimulation, eliciting rightward optokinetic nystagmus and its fixation suppression in 12 healthy volunteers. Bilateral patterns of activation in the visual cortex, including the motion-sensitive area MT/V5, and deactivations in an assembly of vestibular areas (posterior insula, thalamus, anterior cingulate gyrus) during optokinetic nystagmus was markedly diminished or totally absent during its fixation suppression. This finding agrees with the concept of a reciprocal inhibitory interaction between the visual-opto…
Hemispatial neglect reflected on visual memory
2011
PURPOSE Recent studies of hemispatial neglect have revealed both lateralized and nonlateralized attention mechanisms contributing to the syndrome. In addition, neglect patients show impaired spatial working memory and diminished working memory capacity. The aim of this study was to investigate, how neglect would be reflected in their performances in commonly used clinical visual memory tests. METHODS Twelve patients with right hemisphere lesions and left neglect and twelve matched controls were assessed with the Behavioural Inattention Test, the visual reproduction of the WMS-R, the object memory test, the Rey figure test and the list learning test. Visuo-spatial span was explored with the …
Multisensorial Perception in Chronic Migraine and the Role of Medication Overuse.
2020
Multisensory processing can be assessed by measuring susceptibility to crossmodal illusions such as the Sound-Induced Flash Illusion (SIFI). When a single flash is accompanied by 2 or more beeps, it is perceived as multiple flashes (fission illusion); conversely, a fusion illusion is experienced when more flashes are matched with a single beep, leading to the perception of a single flash. Such illusory perceptions are associated to crossmodal changes in visual cortical excitability. Indeed, increasing occipital cortical excitability, by means of transcranial electrical currents, disrupts the SIFI (ie, fission illusion). Similarly, a reduced fission illusion was shown in patients with episod…
Long-term sensorimotor and therapeutical effects of a mild regime of prism adaptation in spatial neglect
2015
International audience; Spatial neglect (SN) is commonly associated with poor functional outcome. Adaptation to a rightward optical deviation of vision has been shown to benefit to SN rehabilitation. The neurophysiological foundations and the optimal modalities of prism adaptation (PA) therapy however remain to be validated. This study is aimed at exploring the long-term sensory-motor, cognitive and functional effects produced by weekly PA sessions over a period of four weeks. A double-blind, monocentric randomized and controlled trial (RCT) was carried out. Twenty patients with left SN secondary to stroke were included, 10 in the “prism” group and 10 in the “control” group. The sensory-mot…
Trait anxiety and autonomic indicators of the processing of threatening information: a cued S1-S2 paradigm.
2004
Abstract The aim of this study was to use autonomic parameters in a cued S1–S2 task to examine associations between the processing of threatening information and trait anxiety in normal individuals. Forty-six student volunteers were designated high- or low-anxious due to pre-defined cutoff scores on the STAI. A cued S1–S2 task was presented in which the type of warning signal (S1) was consistently related to either threatening or non-threatening pictures (S2). Ten threat and 10 non-threat pictures were randomly presented. Heart rate and electrodermal activity were recorded in the time interval between S1 and S2. Results indicated deeper heart rate decelerations on threatening trials in high…
Sex differences in interhemispheric communication during face identity encoding: Evidence from ERPs
2013
Sex-related hemispheric lateralization and interhemispheric transmission times (IHTTs) were examined in twenty-four participants at the level of the first visual ERP components (P1 and N170) during face identity encoding in a divided visual-field paradigm. While no lateralization-related and sex-related differences were reflected in the P1 characteristics, these two factors modulated the N170. Indeed, N170 amplitudes indicated a right hemisphere (RH) dominance in men (and a more bilateral functioning in women). N170 latencies and the derived IHTTs confirmed the RH advantage in men but showed the reverse asymmetry in women. Altogether, the results of this study suggest a clear asymmetry in m…
Effects of post-extinction l-DOPA administration on the spontaneous recovery and reinstatement of fear in a human fMRI study
2015
Relapse is a pertinent problem in the treatment of anxiety disorders. In the laboratory, relapse is modeled as return of conditioned fear responses after successful fear extinction and is explained by insufficient retrieval and/or expression of the fear-inhibitory extinction memory that is generated during extinction learning. We have shown in mice and humans that return of fear can be prevented by administration of a single dose of the dopamine precursor l-3,4-dihydroxyphenylalanine (l-DOPA) immediately after extinction. In mice, this effect could be attributed to an enhancement of extinction memory consolidation. In our human study, we could not exclude that l-DOPA might have acted by int…
Interactive effects of avoidant coping and parental hypertension on Rate Pressure Product reactivity in women
2005
Background: Previous research suggests that personality, situational context variables, and genes might interact to potentiate cardiovascular stress responses.Purpose: Our purpose is to examine interactive effects of dispositional avoidant coping and parental hypertension on cardiovascular reactivity to three different laboratory stressors.Method: Participants were 63 healthy female students. Stressors were an evaluated videotaped speech, the cold pressor, and viewing of the speech video. Heart rate and blood pressure were continuously recorded during baselines and tasks.Results: After controlling for age, body mass index, smoking status, reported exercise, alcohol consumption, oral contrac…
Understanding metaphors and idioms: A single-case neuropsychological study in a person with Down syndrome
2001
The ability of subject F.F., diagnosed with Down syndrome, to appreciate nonliteral (interpreting metaphors and idioms) and literal (vocabulary knowledge, including highly specific and unusual items) aspects of language was investigated. F.F. was impaired in understanding both metaphors and idioms, while her phonological, syntactic and lexical–semantic skills were largely preserved. By contrast, some aspects of F.F.'s executive functions and many visuospatial abilities were defective. The suggestion is made that the interpretation of metaphors and idioms is largely independent of that of literal language, preserved in F.F., and that some executive aspects of working memory and visuospatial …
Chromatic and achromatic visual fields in relation to choroidal thickness in patients with high myopia: A pilot study
2018
Purpose. - To analyse the relationship between the choroidal thickness and the visual perception of patients with high myopia but without retinal damage. Methods. - All patients underwent ophthalmic evaluation including a slit lamp examination and dilated ophthalmoscopy, subjective refraction, best corrected visual acuity, axial length, optical coherence tomography, contrast sensitivity function and sensitivity of the visual pathways. Results. - We included eleven eyes of subjects with high myopia. There are statistical correlations between choroidal thickness and almost all the contrast sensitivity values. The sensitivity of magnocellular and koniocellular pathways is the most affected, an…