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

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.

A Comparison of Cardinal Gaze Speed between Major League Baseball Players, Amateur Prospects, and Non-athletes

“…Vision training drills can also be repeated to induce eye fatigue and ultimately train more consistent performance over time. 32 In summary, this study showed significant differences in the speed of eye movements in the CGPs between MLB players, amateur prospects, and non-athletes. The study also showed significant differences in the speed of eye movements in the different cardinal gaze directions.…”

Brain Activation Patterns Characterizing Different Phases of Motor Action: Execution, Choice and Ideation

“…Moreover, parietooccipital regions have been found active in motor ideation. These areas are deputed to spatial representation (Pellegrino et al, 2015), visuo-perceptual processing (Coubard et al, 2014) and visual mental imagery (Gardini et al, 2005;Gardini et al, 2006). Recent evidence (Pellegrino et al, 2015) suggests that the brain constructs multiple representations of space, centred on different body parts (e.g., hand-centred), which arise through extensive multisensory interactions within a set of interconnected parietal and frontal regions.…”

Visual rehabilitation: visual scanning, multisensory stimulation and vision restoration trainings

“…In general, however, there is no additional spontaneous recovery beyond the first few months, and the HVFD is considered to be permanent. As a consequence, since the late 70–80 s the combined efforts of neuropsychological research and clinical practice have sought to achieve HVDF improvements in the post-acute stage of recovery through visual rehabilitation (for early rehabilitation studies, see Ben-Yishay and Diller, 1981 , 1993 ; Ducarne and Barbeau, 1981 ; Ducarne et al, 1981 ; for a review, see Coubard et al, 2014 ). In this perspective, the term visual rehabilitation (Kerkhoff, 2000 ; Zihl, 2010 ) refers to all the rehabilitation strategies aiming to improve hemianopic patients’ independent living and quality of life, promoting functional restitution of the impaired visual function (restoration approaches), the acquisition of compensatory strategies relying on the intact functions (compensatory approaches) or the adaptation of the environment to the patient’s impairment, through artificial devices (substitution approaches).…”