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J F Legargasson

Publications and source records attributed to J F Legargasson.

9 recordsLinked to original sources
PubMed2006

Evolution of subjective visual vertical perturbation after stroke.

OBJECTIVE: The perception of visual verticality is often perturbed after stroke and might be an underlying component of imbalance. The aim of this study was to describe the evolution of visual vertical (VV) perturbation and to investigate the factors affecting it. METHODS: Thirty patients with hemiplegia after a single hemispheric stroke (17 left lesioned [LL] and 13 right lesioned [RL]) were studied. Visual verticality was tested within 45 days of stroke, and then at 3 and 6 months. Subjects sat in a dark room and adjusted a luminous rod to the vertical position. The differences between patients' adjustments and vertical were calculated. The effects on VV evolution of the side, size, type, and location of the lesion were tested. RESULTS: Sixty percent of the recent stroke patients had an initial inaccurate perception of verticality, and 39% of these patients recovered during the 1st 3 months after stroke. The evolution of VV tilt depended on the side of the lesion (P = 0.01), with better recovery in LL patients. None of the other factors studied affected VV normalization. CONCLUSIONS: The poorer recovery of vertical perception after right-side stroke might be due to the predominant role of the right hemisphere in spatial cognition, and might be involved in the poorer recovery of balance after stroke in RL patients.

Adult↗
PubMed2001

Ocular fundus images with confocal scanning laser ophthalmoscopy in the dog, monkey and minipig.

Confocal scanning laser ophthalmoscopy (CSLO) is a new technique that enables ocular fundus image recording and retinal dynamic angiography to be performed. The ocular fundus image is acquired sequentially, point by point, and is reconstructed on a video monitor at the rate of 25 images per second. The feasibility of performing both ocular fundus image recordings and retinal angiography image recordings were tested on two dogs, two monkeys and two minipigs using a 40 degrees field I + Tech CSLO. Fundus area of each dog, monkey and minipig were examined without any additional optical devices. The ocular fundus and angiography images were recorded, stabilized and analyzed under the same conditions. For each species, all images were easily recorded without any additional optical device in a lighted room and the morphology of the retinal images generated was similar to those obtained with a camera or angiography of higher resolution. Capillary phase or venous times are presented. Image recording at 25 frames/second enabled more retinal dynamics to be demonstrated than with use of regular angiography. This technique is noninvasive and easy to perform if the eye is fixed and eyelids maintained open. It also allows exploration of retinal microvascularization and could be utilized for clinical, pharmacologic and toxicologic investigations as well.

Animals↗
PubMed1989

Data processing software for electrophysiological visual exploration.

The software we have developed originated after careful study of a routine functional visual processing session. It has three objectives: (i) to have available a large library of data processing programs; (ii) to add to these electrophysiological results, automatically transferred into a file, a clinical record card, creating a personalized file for study of visual characteristics of each patient; (iii) to allow programs providing statistical studies, creation of groups based on the same clinical features and various comparisons between files or groups. The database now contains 5000 different files and the results of its use are very encouraging. Some results are presented, especially those of a study on multiple sclerosis. The goal of the operation is the creation, in the future, of an expert system.

Clinical Laboratory Information Systems↗
PubMed1985

Correlation functions in the analysis of visual evoked potentials.

Our "vision" laboratory has been working for several years on stimulation methods and data processing. We present here the results of an analysis of correlation functions between VEPs obtained by flashes and patterned stimulations. This study provides additional information about possible interpretations.

Evoked Potentials, Visual↗
PubMed1985

[Methods of stimulation in visual electrophysiology].

After introducing physical and physiological stimulation parameters, the authors present different techniques and discuss their clinical usefulness for the investigation of the visual system: flashes: chiefly 'ganzfeld' stimulators (whole field or local stimulation). A solution using optic fibres incorporated in a sclero-corneal electrode built in our laboratory is presented; patterns: bars or chekerboards, especially on TV screens. Advantages and inconveniences of video images are discussed; other techniques: essentially endocular laser interference fringes, electrical stimulations, high level flashes for ERP and binocular studies, particularly dynamic random dot pattern EVP. In conclusion, the necessity for the careful control of stimulation characteristics and for a strategy suitable for clinical examination is discussed.

Brain↗