Fig. 5.

Residual vision and brain network amplification. (A) This graph serves only as a conceptual guide to appreciate the nature of residual vision and the interactions of retina and brain by neuronal oscillatory activity. Accordingly, vision loss (e.g. measured by detection ability) depends on how many cells are lost: the greater the cell loss, the greater is the defect in different regions of the visual field. Areas of residual vision (ARVs; shown in grey) correspond to regions of partial damage with or without vascular dysregulation. They are found in all kinds of visual field defects such as after stroke (e.g. hemianopia) or retinal or optic nerve damage (e.g. glaucoma). Black areas represent complete damage. Note, however, that many black regions may, in fact, have some residual visual function as well. (B) Whether or not visual stimuli processes by the retina are consciously perceived by the brains is not only determined by the strength of the neuronal signals sent by the retina to the brain, but it also depends on how the brain processes this information through synchronization, amplification and interpretation. Neural activity of the retina is represented here by a simple sine wave. If the brain network is disorganized (illustrated here by non-synchronized, out-of-phase brain sine waves), the sum of retinal and brain signals is too low to surpass the perceptual threshold and the visual stimulus is not perceived. When the brain is synchronized, this elevates (amplifies) the same residual visual signal to above-threshold perception, thus improving or restoring conscious vision.