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Educating the blind brain: a panorama of neural bases of vision and of training programs in organic neurovisual deficits.

Coubard OA, Urbanski M, Bourlon C, Gaumet M - Front Integr Neurosci (2014)

Bottom Line: The visual system involves five main routes originating in the retinas but varying in their destination within the brain: the occipital cortex, but also the superior colliculus (SC), the pretectum, the supra-chiasmatic nucleus, the nucleus of the optic tract and terminal dorsal, medial and lateral nuclei.Organic neurovisual deficits may occur at any level of this circuitry from the optic nerve to subcortical and cortical destinations, resulting in low or high-level visual deficits.Given the extent of its neural bases in the brain, vision in its motor and perceptual aspects is also a useful tool to assess and modulate central nervous system (CNS) in general.

View Article: PubMed Central - PubMed

Affiliation: The Neuropsychological Laboratory, CNS-Fed Paris, France ; Laboratoire Psychologie de la Perception, UMR 8242 CNRS-Université Paris Descartes Paris, France.

ABSTRACT
Vision is a complex function, which is achieved by movements of the eyes to properly foveate targets at any location in 3D space and to continuously refresh neural information in the different visual pathways. The visual system involves five main routes originating in the retinas but varying in their destination within the brain: the occipital cortex, but also the superior colliculus (SC), the pretectum, the supra-chiasmatic nucleus, the nucleus of the optic tract and terminal dorsal, medial and lateral nuclei. Visual pathway architecture obeys systematization in sagittal and transversal planes so that visual information from left/right and upper/lower hemi-retinas, corresponding respectively to right/left and lower/upper visual fields, is processed ipsilaterally and ipsialtitudinally to hemi-retinas in left/right hemispheres and upper/lower fibers. Organic neurovisual deficits may occur at any level of this circuitry from the optic nerve to subcortical and cortical destinations, resulting in low or high-level visual deficits. In this didactic review article, we provide a panorama of the neural bases of eye movements and visual systems, and of related neurovisual deficits. Additionally, we briefly review the different schools of rehabilitation of organic neurovisual deficits, and show that whatever the emphasis is put on action or perception, benefits may be observed at both motor and perceptual levels. Given the extent of its neural bases in the brain, vision in its motor and perceptual aspects is also a useful tool to assess and modulate central nervous system (CNS) in general.

No MeSH data available.


Related in: MedlinePlus

(A) Retina or nervous layer of the eye. Light information cross the retina (arrows) to reach sensory cells, cones (1a—fovea) and rods (1b—peripheral retina), which transform light information into neural information. Neural information is transferred to bipolar neurons (2), then to ganglion neurons (3). Fibers of the latter exit the retina (4) and merge into the optic nerve. (B) Lateral systematization of the retino-occipital visual pathway. (1) Lesion of optic nerve causes monocular blindness. (2) Lesion of optic chiasma causes bitemporal hemianopia. (3) Unilateral lesion of direct temporal fibers causes monocular nasal blindness. (4) Unilateral lesion of optic tract, or (7) of both lower and upper optic radiations, or (8) of primary visual cortex causes homonymous hemianopia (HH). (5) Unilateral lesion of lower optic radiations causes homonymous superior quadrantanopia. (6) Unilateral lesion of upper optic radiations causes homonymous inferior quadrantanopia. (A) Adapted from Bear et al. (1997, p. 224, Figure 9.14) (© O.A. Coubard, with permission); (B) Adapted from www.chups.jussieu.fr/ polys /neuro/ semioneuro/ POLY.Chp.3.6.3. html, Figure 8 (© O.A. Coubard, with permission).
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Figure 5: (A) Retina or nervous layer of the eye. Light information cross the retina (arrows) to reach sensory cells, cones (1a—fovea) and rods (1b—peripheral retina), which transform light information into neural information. Neural information is transferred to bipolar neurons (2), then to ganglion neurons (3). Fibers of the latter exit the retina (4) and merge into the optic nerve. (B) Lateral systematization of the retino-occipital visual pathway. (1) Lesion of optic nerve causes monocular blindness. (2) Lesion of optic chiasma causes bitemporal hemianopia. (3) Unilateral lesion of direct temporal fibers causes monocular nasal blindness. (4) Unilateral lesion of optic tract, or (7) of both lower and upper optic radiations, or (8) of primary visual cortex causes homonymous hemianopia (HH). (5) Unilateral lesion of lower optic radiations causes homonymous superior quadrantanopia. (6) Unilateral lesion of upper optic radiations causes homonymous inferior quadrantanopia. (A) Adapted from Bear et al. (1997, p. 224, Figure 9.14) (© O.A. Coubard, with permission); (B) Adapted from www.chups.jussieu.fr/ polys /neuro/ semioneuro/ POLY.Chp.3.6.3. html, Figure 8 (© O.A. Coubard, with permission).

Mentions: A first striking feature of vision is retinal inversion (see Figure 5A). After light information has crossed the cornea, the anterior chamber, the pupil, the lens, the posterior chamber, it has to cross all layers of the retina, as it is inversed, to reach sensory cells. Indeed, cones and rods are opposite to the light for a reason that is hitherto unknown, except that their metabolic and photopigment regeneration requirements need ready access to the choroidal blood supply in the deepness of the retina. Once sensory cells have transformed light into neural information, the latter is transferred to bipolar neuron then to ganglion ones as described above (see Section The Seeing Brain from Eye to Cortex). Due to retinal inversion, ganglion neuron fibers exit the eye making a hole in the retina, the blind spot, to merge into the optic nerve (see Figure 5A). Retinotopy, that is the way information is spatially organized on the retina, is preserved throughout visual pathways and is retrieved particularly in SC and primary visual cortex (Dowling, 1970; Tamraz et al., 1999; Chalupa and Werner, 2003; Podoleanu, 2012; see Figure 2C).


Educating the blind brain: a panorama of neural bases of vision and of training programs in organic neurovisual deficits.

Coubard OA, Urbanski M, Bourlon C, Gaumet M - Front Integr Neurosci (2014)

(A) Retina or nervous layer of the eye. Light information cross the retina (arrows) to reach sensory cells, cones (1a—fovea) and rods (1b—peripheral retina), which transform light information into neural information. Neural information is transferred to bipolar neurons (2), then to ganglion neurons (3). Fibers of the latter exit the retina (4) and merge into the optic nerve. (B) Lateral systematization of the retino-occipital visual pathway. (1) Lesion of optic nerve causes monocular blindness. (2) Lesion of optic chiasma causes bitemporal hemianopia. (3) Unilateral lesion of direct temporal fibers causes monocular nasal blindness. (4) Unilateral lesion of optic tract, or (7) of both lower and upper optic radiations, or (8) of primary visual cortex causes homonymous hemianopia (HH). (5) Unilateral lesion of lower optic radiations causes homonymous superior quadrantanopia. (6) Unilateral lesion of upper optic radiations causes homonymous inferior quadrantanopia. (A) Adapted from Bear et al. (1997, p. 224, Figure 9.14) (© O.A. Coubard, with permission); (B) Adapted from www.chups.jussieu.fr/ polys /neuro/ semioneuro/ POLY.Chp.3.6.3. html, Figure 8 (© O.A. Coubard, with permission).
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Related In: Results  -  Collection

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Figure 5: (A) Retina or nervous layer of the eye. Light information cross the retina (arrows) to reach sensory cells, cones (1a—fovea) and rods (1b—peripheral retina), which transform light information into neural information. Neural information is transferred to bipolar neurons (2), then to ganglion neurons (3). Fibers of the latter exit the retina (4) and merge into the optic nerve. (B) Lateral systematization of the retino-occipital visual pathway. (1) Lesion of optic nerve causes monocular blindness. (2) Lesion of optic chiasma causes bitemporal hemianopia. (3) Unilateral lesion of direct temporal fibers causes monocular nasal blindness. (4) Unilateral lesion of optic tract, or (7) of both lower and upper optic radiations, or (8) of primary visual cortex causes homonymous hemianopia (HH). (5) Unilateral lesion of lower optic radiations causes homonymous superior quadrantanopia. (6) Unilateral lesion of upper optic radiations causes homonymous inferior quadrantanopia. (A) Adapted from Bear et al. (1997, p. 224, Figure 9.14) (© O.A. Coubard, with permission); (B) Adapted from www.chups.jussieu.fr/ polys /neuro/ semioneuro/ POLY.Chp.3.6.3. html, Figure 8 (© O.A. Coubard, with permission).
Mentions: A first striking feature of vision is retinal inversion (see Figure 5A). After light information has crossed the cornea, the anterior chamber, the pupil, the lens, the posterior chamber, it has to cross all layers of the retina, as it is inversed, to reach sensory cells. Indeed, cones and rods are opposite to the light for a reason that is hitherto unknown, except that their metabolic and photopigment regeneration requirements need ready access to the choroidal blood supply in the deepness of the retina. Once sensory cells have transformed light into neural information, the latter is transferred to bipolar neuron then to ganglion ones as described above (see Section The Seeing Brain from Eye to Cortex). Due to retinal inversion, ganglion neuron fibers exit the eye making a hole in the retina, the blind spot, to merge into the optic nerve (see Figure 5A). Retinotopy, that is the way information is spatially organized on the retina, is preserved throughout visual pathways and is retrieved particularly in SC and primary visual cortex (Dowling, 1970; Tamraz et al., 1999; Chalupa and Werner, 2003; Podoleanu, 2012; see Figure 2C).

Bottom Line: The visual system involves five main routes originating in the retinas but varying in their destination within the brain: the occipital cortex, but also the superior colliculus (SC), the pretectum, the supra-chiasmatic nucleus, the nucleus of the optic tract and terminal dorsal, medial and lateral nuclei.Organic neurovisual deficits may occur at any level of this circuitry from the optic nerve to subcortical and cortical destinations, resulting in low or high-level visual deficits.Given the extent of its neural bases in the brain, vision in its motor and perceptual aspects is also a useful tool to assess and modulate central nervous system (CNS) in general.

View Article: PubMed Central - PubMed

Affiliation: The Neuropsychological Laboratory, CNS-Fed Paris, France ; Laboratoire Psychologie de la Perception, UMR 8242 CNRS-Université Paris Descartes Paris, France.

ABSTRACT
Vision is a complex function, which is achieved by movements of the eyes to properly foveate targets at any location in 3D space and to continuously refresh neural information in the different visual pathways. The visual system involves five main routes originating in the retinas but varying in their destination within the brain: the occipital cortex, but also the superior colliculus (SC), the pretectum, the supra-chiasmatic nucleus, the nucleus of the optic tract and terminal dorsal, medial and lateral nuclei. Visual pathway architecture obeys systematization in sagittal and transversal planes so that visual information from left/right and upper/lower hemi-retinas, corresponding respectively to right/left and lower/upper visual fields, is processed ipsilaterally and ipsialtitudinally to hemi-retinas in left/right hemispheres and upper/lower fibers. Organic neurovisual deficits may occur at any level of this circuitry from the optic nerve to subcortical and cortical destinations, resulting in low or high-level visual deficits. In this didactic review article, we provide a panorama of the neural bases of eye movements and visual systems, and of related neurovisual deficits. Additionally, we briefly review the different schools of rehabilitation of organic neurovisual deficits, and show that whatever the emphasis is put on action or perception, benefits may be observed at both motor and perceptual levels. Given the extent of its neural bases in the brain, vision in its motor and perceptual aspects is also a useful tool to assess and modulate central nervous system (CNS) in general.

No MeSH data available.


Related in: MedlinePlus