Head-eye movement control model based on genetically selected neural network.
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Biomedical subjects
Publications and source records attributed to M Capozza.
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PURPOSE: To detect mild visual field impairment in asymptomatic glaucoma suspect patients. METHODS: Color perception within the visual field was tested with customized color video perimetry. The key features of the system were stimuli color desaturation, low-level luminance and equiluminant gray background. Twenty patients with asymptomatic glaucoma were tested and compared with a group of age-matched control subjects. RESULTS: Automated perimetry test findings differed significantly in the two groups, particularly for short-wavelength sensitivity (blue). The severity of color impairment correlated directly with intraocular pressure. CONCLUSION: Desaturated low-luminance video perimetry will reliably detect and quantify asymptomatic visual field defects. A previous work on multiple sclerosis has detected a mild long-wavelength (red) impairment in asymptomatic patients after an episode of optic neuritis, even in clinically unaffected fellow eyes. Our findings in glaucoma suspect patients indicate that a mild blue impairment could be the initial sign of this disease.
The human brainstem is a highly complex structure where even small lesions can give rise to a variety of symptoms and outward signs. Localising the area of dysfunction within the brainstem is often a difficult task. To make localisation easier, a neural net system has been developed which uses 72 clinical and neurophysiological data inputs to provide a display (using 5268 voxels) on a three-dimensional model of the human brainstem. The net was trained by means of a back-propagation algorithm, over a pool of 580 example cases. Assessed on 200 test cases, the net correctly localised 83.6% of the target voxels; furthermore the net correctly localised the lesions in 31 out of 37 patients. Because this computer-assisted method provides reliable and quantitative localisation of brainstem areas of dysfunction and can be used as a 3D interactive functional atlas, it is expected to prove useful as a diagnostic tool for assessing focal brainstem lesions.
Color visual field analysis has proven highly sensitive for early visual impairments diagnosis in MS, yet it has never attained widespread popularity usually because the procedure is difficult to standardize, the devices are costly, and the test is fatiguing. We propose a computerized procedure running on standard PC, cost effective, clonable, and easy handled. Two hundred and sixty-four colored patches subtending 1 degree angle vision, with selected hues and low saturation levels are sequentially and randomly displayed on gray equiluminous background of the PC screen subtending 24 degrees x 40 degrees angle of vision. The subject is requested to press a switch at the perception of the stimulus. The output provides colored maps with quantitative information. Comparison between normals and a selected population of MS patients with no actual luminance visual field defects, showed high statistical difference.
Unlike conventional platform posturography, which analyses the sway in the projection of the body baricentre on a supporting plane, multisegmental posturography provides information about body segmental movements during stance, including those that keep the baricentre still. This paper presents a new technical approach to multisegmental posturography using Virtual Reality electromagnetic tracking devices. This device was used to study age-related differences in normal subjects in the control of upright posture. Body sway was studied by recording the oscillations of two trackers placed on the head and the hip during the Romberg test. The tracking device allowed us to detect age-related differences in postural stance strategies. Although the amplitude and velocity of the oscillations measured at the head did not differ in the two groups, the flexibility of the ankle-hip head axis differed significantly: elderly subjects exhibited a more rigid stance. Closing the eyes increased rigidity in both age groups and this change appear more pronounced in the young.
Color visual field analysis has proven highly sensitive for early visual impairments diagnosis in M. S., yet it has never attained widespread popularity usually because the procedure is difficult to standardize, the devices are costly, and the test is fatiguing. We propose a computerized procedure running on standard PC, cost effective, clonable, and easy handled. 264 colored patches subtending 1 degree angle of vision, with selected hues and low saturation levels are sequentially and randomly displayed on gray equiluminous background of the PC screen subtending 24 degrees x 40 degrees angle of vision. The subject is requested to press a switch at the perception of the stimulus. The output provides colored maps with quantitative informations. Comparison between normals and a selected population of Patients with Multiple Sclerosis and with Glaucoma without luminance visual field defects, showed high statistical difference.
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Clobazam was compared with placebo as antiepileptic adjunct medication in 129 therapy-resistant epileptic patients who were mainly suffering from complex partial seizures. The study was performed in five European countries according to a double-blind crossover design lasting 7 months. Two treatment periods of 3 months (1 month adjustment and 2 months maintenance medication) were separated by one medication switch-over month. The difference in seizure reduction between clobazam and placebo was significant (p less than 0.05). Nineteen percent of patients receiving clobazam became seizure-free during the maintenance dose period. In contrast, freedom from seizures was not observed in any placebo patient. Electroencephalogram (EEG) signs, mood ratings, and global impressions also indicated therapeutic effects of clobazam in epilepsy. The most frequent adverse reactions to clobazam were drowsiness and dizziness. However, the sedative effects of clobazam seemed to be less pronounced in comparison with other benzodiazepines. The study gives evidence of the therapeutic value of clobazam as adjunct medication in therapy-resistant partial seizures. The use of clobazam as monotherapy and long-term treatment, as well as the particular seizure response pattern to clobazam, has to be further investigated.