Attention and Amblyopia
نویسندگان
چکیده
IN a previous paper (van Balen and Henkes, 1960) we indicated the possibility of recording the response of the occipital lobe to light-stimulation in man. The use of Dawson's superimposition method together with the mathematical integration method enabled us to record the responses in all normal subjects. The specific response of the visual cortex consists of four different components: a small surface-positive wave a, followed by a somewhat larger negative wave b, then by the main positive deflection c and a smaller negative deflection d (van Balen and Henkes, 1960, Fig. 5). The positive deflection c consists of two components: cl and c2. A study of the specific response to light stimulation of varying intensities and at different levels of dark adaptation revealed the correspondence of the amplitude of the cl-wave with the level of activity of the photopic mechanism, and of the amplitude of the c2wave with the level of activity of the scotopic mechanism. The photopic and scotopic mechanisms, however, are concepts of the physiology of the retina and coincide more or less with the anatomical concepts of cones and rods. In the ganglion cell layer of the retina a regrouping occurs. Foveal cones in monosynaptic units form the foveal system; peripheral cones and rods in polysynaptic units form the extra-foveal system. Anatomically the foveal and extra-foveal systems can be distinguished in all parts of the visual system. In the visual cortex (striate area), for instance, a foveal (" macular") and extrafoveal ("extra-macular") projection field can be distinguished. These data lead one to expect the separate representation of the foveal and extra-foveal systems in the occipital response.
منابع مشابه
Investigating the Relationship of Visual Treatment and Rehabilitation With the Quality of Life and Visual Status in Children With Diagnosed Amblyopia
Objectives: To assess the relationship between visual rehabilitation with the quality of life and visual status in children who had been diagnosed with amblyopia in the national amblyopia screening program. Methods: Information was gathered from optometric centers in the cities of Nowshahr, Chalus, and Kelardasht, or in case it was not available, from parents of participating children. The KIN...
متن کاملprevalence of Amblyopia in 7-8 year old students of primary schools of Kerman city during the year 1996.
Amblyopia is an acquired defect in ocular vision that is due to abnormal visual acuity which can be unilateral of bilateral,and can not be directly related to structural defects or optic radiation.Amblyopia can be effectively treated during the first decade of lift in most cases.for this reason in a cross sectional study in 1996 with multistage random sampling 1726 students in age 7-8 years old...
متن کاملDegraded attentional modulation of cortical neural populations in strabismic amblyopia
Behavioral studies have reported reduced spatial attention in amblyopia, a developmental disorder of spatial vision. However, the neural populations in the visual cortex linked with these behavioral spatial attention deficits have not been identified. Here, we use functional MRI-informed electroencephalography source imaging to measure the effect of attention on neural population activity in th...
متن کاملThe Role of Eye Movement Driven Attention in Functional Strabismic Amblyopia
Strabismic amblyopia "blunt vision" is a developmental anomaly that affects binocular vision and results in lowered visual acuity. Strabismus is a term for a misalignment of the visual axes and is usually characterized by impaired ability of the strabismic eye to take up fixation. Such impaired fixation is usually a function of the temporally and spatially impaired binocular eye movements that ...
متن کاملSurvey on the Opinion of Ophthalmologists and Optometrists about Amblyopia Treatment Compared to Standard Treatment in Guilan Province
Purpose: To evaluate the opinion of the ophthalmologists and optometrists in Guilan Province about different aspects of amblyopia treatment. Methods: A questionnaire was designed to evaluate the opinion of 30 ophthalmologists and 20 optometrists about different aspects of amblyopia treatment, including the age of initiation and termination of treatment, different treatment modalities, and maint...
متن کامل