Structural brain plasticity induced by early blindness

Abstract

It is well established that early blindness results in behavioural adaptations. While the functional effects of visual deprivation have been well researched, anatomical studies are scarce. The aim of this study was to investigate whole brain structural plasticity in a mouse model of congenital blindness. Volumetric analyses were conducted on high‐resolution MRI images and histological sections from the same brains. These morphometric measurements were compared between anophthalmic and sighted ZRDBA mice obtained by breeding ZRDCT and DBA mice. Results from MRI analyses using the Multiple Automatically Generated Templates (MAGeT) method showed smaller volume for the primary visual cortex and superior colliculi in anophthalmic compared with sighted mice. Deformation‐based morphometry revealed smaller volumes within the dorsal lateral geniculate nuclei and the lateral secondary visual cortex and larger volumes within olfactory areas, piriform cortex, orbital areas and the amygdala, in anophthalmic compared with sighted mice. Histological analyses revealed a larger volume for the amygdala and smaller volume for the superior colliculi, primary visual cortex and medial secondary visual cortex, in anophthalmic compared with sighted mice. The absence of superficial visual layers of the superior colliculus and the thinner cortical layer IV of the primary and secondary visual cortices may explain the smaller volume of these areas, although this was observed in a limited sample. The present study shows large‐scale brain plasticity in a mouse model of congenital blindness. In addition, the congruence of MRI and histological findings support the use of MRI to investigate structural brain plasticity in the mouse.

Anxiety and Depression Assessments in a Mouse Model of Congenital Blindness

“…Nevertheless, a recent study conducted on the ZRDBA strain found that dark-reared sighted mice from birth show similar hypersensitivity than their anophthalmic counterparts, underlying that these results applied to early visual deprivation in general and they were not specific to mice devoid of the visual system (Touj et al, 2021b). More importantly, it has been largely investigated that early visual deprivation (regardless of the etiologies) leads to dramatic behavioral and brain plasticity in humans, consistent with murine models, especially on most of sensory systems (Kupers and Ptito, 2014;Renier et al, 2014;Zhou et al, 2017;Touj et al, 2020Touj et al, , 2021a.…”

“…The question remains, how did they detect the wall or the border of the behavioral device, and which non-visual perceptions or sensory modalities contribute to spatial navigation in blind mice. A large body of evidence showed that early blindness (due to retinopathy of prematurity, glaucoma and cataract) results in an enhancement of the remaining non-visual modalities in humans (Van Boven et al, 2000;Beaulieu-Lefebvre et al, 2011;Renier et al, 2014), as well as in mice (Zhou et al, 2017;Touj et al, 2019Touj et al, , 2020Touj et al, , 2021a. All of these behavioral changes are supported by brain plasticity and reorganization (Kupers and Ptito, 2014;Chebat et al, 2020;Touj et al, 2020).…”

Heritable functional architecture in human visual cortex

“…Nevertheless, there is great experience-dependent plasticity in the development of functional response properties of visual cortex ( Hubel and Wiesel, 1965 ; Wiesel and Hubel, 1965a , 1965b ). Early blindness causes structural changes in visual brain regions ( Touj et al, 2020 ), possibly due to functional reorganization to serve other functions ( Burton, 2003 ). Spatial selectivity of visual cortex, as measured by pRF size, is also abnormal in individuals with amblyopia ( Clavagnier et al, 2015 ).…”

Heritable functional architecture in human visual cortex

“…Nevertheless, there is of course great experience-dependent plasticity in the development of functional response properties of visual cortex (Hubel and Wiesel, 1965; Wiesel and Hubel, 1965a, 1965b). Early blindness causes structural changes in visual brain regions (Touj et al, 2020), possibly due to functional reorganization to serve other functions (Burton, 2003). Spatial selectivity of visual cortex, as measured by pRF size, is also abnormal in individuals with amblyopia (Clavagnier et al, 2015).…”