The Implications of Brain Plasticity and Task Selectivity for Visual Rehabilitation of Blind and Visually Impaired Individuals

Neural Networks Mediating Perceptual Learning in Congenital Blindness

“…In addition, a cascade of other non-visual brain structures undergo anatomical 18 , morphological 19 , and morphometric [20][21][22][23] alterations, as well as modifications in functional connectivity 24 . There is no doubt that the brain of born blind individuals undergoes substantial reorganization compared to the sighted and is still able to carry out a number of behavioral tasks including navigation see 25,26 for recent reviews with the use of sensory substitution devices (SSDs).…”

“…CBs' preserved navigational skills correlate with a larger anterior hippocampus 10 that is accompanied by a volume reduction of its posterior portion 9 . These findings were explained by the possibility that the blind may rely more heavily on structures other than the hippocampus (such as the posterior parietal cortex) for navigation ( 31,25 ). The taxing demands of learning to detect and avoid obstacles without vision may drive hippocampal plasticity and volumetric changes in CB 9,11,15,32 .…”

Spatial Competence and Brain Plasticity in Congenital Blindness via Sensory Substitution Devices

“…Visual deprivation from birth leads to anatomical volumetric reductions of all components of the visual system, from the retina to the thalamic primary visual relay (dorsal lateral geniculate nucleus) (Cecchetti et al, 2016b), the visual cortex and extrastriate cortices including the ventral and dorsal streams (Ptito et al, 2008b). These structures have been shown to reorganize and develop ectopic projections with other sensory cortices mostly touch and audition (reviewed in Kupers and Ptito, 2014;Chebat et al, 2018b;Harrar et al, 2018). Indeed, CB trained with SSDs activate their primary visual cortex (Ptito, 2005) in a tactile orientation task, and the dorsal visual and ventral streams for tactile motion (Ptito et al, 2009) and the perception of tactile form (Ptito et al, 2012).…”

“…This process, known as amodality ( Heimler et al, 2015 ; Chebat et al, 2018b ) enables the recruitment of brain areas in a task specific, sensory independent fashion ( Cohen et al, 1997 ). The recruitment of task-specific brain nodes for shapes ( Ptito et al, 2012 ), motion ( Saenz et al, 2008 ; Ptito et al, 2009 ; Matteau et al, 2010 ; Striem-Amit et al, 2012b ), number-forms ( Abboud et al, 2015 ), body shapes ( Striem-Amit and Amedi, 2014 ), colors ( Steven et al, 2006 ), word shapes ( Striem-Amit et al, 2012a ), faces ( Likova et al, 2019 ), echolocation ( Norman and Thaler, 2019 ), and tactile navigation ( Kupers et al, 2010a ; Maidenbaum et al, 2018 ) is thought to represent mechanisms of brain plasticity ( Fine and Park, 2018 ; Singh et al, 2018 ) for specific amodal recruitment ( Ptito et al, 2008a ; Chebat et al, 2018b ; see Figure 2 ). The recruitment of the brain areas via SSDs not only shows that it is possible to supplement missing visual information, but that the brain treats the SSD information as if it were real vision, in the sense that it tries to extract the relevant sensory information for each specific task we are trying to accomplish (i.e., motion, colors, navigation, and other tasks illustrated in Figure 2 ).…”

“…CB can form mental representations of the work space via haptic information as efficiently as sighted people, indicating that this ability does not depend on visual experience ( Nelson et al, 2018 ). People who are congenitally blind are capable of avoiding obstacles ( Kellogg, 1962 ; Chebat et al, 2011 , 2020 ), integrating paths ( Loomis et al, 2012 ), remembering locations ( Chebat et al, 2015 ), and generating cognitive representations of space ( Passini et al, 1990 ; Thinus-Blanc and Gaunet, 1997 ; Fortin et al, 2006 ; Chebat et al, 2018a , b ). As a consequence, CB maintain the ability to recognize a familiar route and represent spatial information ( Marmor and Zaback, 1976 ; Kerr, 1983 ; Passini et al, 1990 ; Loomis et al, 1993 ; Thinus-Blanc and Gaunet, 1997 ; Fortin et al, 2006 ; Leporé et al, 2009 ).…”