Visual Advantage in Deaf Adults Linked to Retinal Changes

Abstract

The altered sensory experience of profound early onset deafness provokes sometimes large scale neural reorganisations. In particular, auditory-visual cross-modal plasticity occurs, wherein redundant auditory cortex becomes recruited to vision. However, the effect of human deafness on neural structures involved in visual processing prior to the visual cortex has never been investigated, either in humans or animals. We investigated neural changes at the retina and optic nerve head in profoundly deaf (N = 14) and hearing (N = 15) adults using Optical Coherence Tomography (OCT), an in-vivo light interference method of quantifying retinal micro-structure. We compared retinal changes with behavioural results from the same deaf and hearing adults, measuring sensitivity in the peripheral visual field using Goldmann perimetry. Deaf adults had significantly larger neural rim areas, within the optic nerve head in comparison to hearing controls suggesting greater retinal ganglion cell number. Deaf adults also demonstrated significantly larger visual field areas (indicating greater peripheral sensitivity) than controls. Furthermore, neural rim area was significantly correlated with visual field area in both deaf and hearing adults. Deaf adults also showed a significantly different pattern of retinal nerve fibre layer (RNFL) distribution compared to controls. Significant correlations between the depth of the RNFL at the inferior-nasal peripapillary retina and the corresponding far temporal and superior temporal visual field areas (sensitivity) were found. Our results show that cross-modal plasticity after early onset deafness may not be limited to the sensory cortices, noting specific retinal adaptations in early onset deaf adults which are significantly correlated with peripheral vision sensitivity.

Finding the balance between capture and control: Oculomotor selection in early deaf adults

“…The present results are particularly interesting in light of the evidence that has related experience-dependent changes within the visual system of deaf adults to feed-forward visual processing (e.g., Bottari, Caclin, et al, 2011;Codina et al, 2011;Scott et al, 2014). This literature on the neural correlates of deafness motivated our initial prediction toward increased saliency capture in deaf adults compared to hearing controls.…”

Attentional spread in deaf and hearing participants: Face and object distractor processing under perceptual load

“…However, the congruency effects did not differ numerically between central and peripheral distractor locations in hearing participants, suggesting that cortical magnification did not play a crucial role here. Furthermore, neural changes in the retinal structures of deaf participants suggested a greater retinal ganglion cell number and were related to an enhanced peripheral vision (Codina et al, 2011), which makes the application of the corticalmagnification factor (Rovamo & Virsu, 1979) to deaf individuals more complex.…”

“…Enhanced reactivity to visual stimuli in deaf participants has also been reported to occur for both central and peripheral stimuli (Bottari, Nava, Ley, & Pavani, 2010;see Pavani & Bottari, 2011, for a recent review). Remarkably, deaf individuals exhibit larger visual fields than do normal-hearing controls (Buckley, Codina, Bhardwaj, & Pascalis, 2010;Codina et al, 2011;Stevens & Neville, 2006). Monitoring moving stimuli in the visual periphery produced higher activation in motion-related areas (middle temporal and medial superior temporal area) in deaf than in hearing participants (Bavelier et al, 2001;Bavelier et al, 2000).…”

Framing Deaf Children’s Right to Sign Language in the Canadian Charter of Rights and Freedoms

“…Bahan (2009) Not only have signed languages arisen to accommodate the visual and tactile abilities of deaf people, but also there are distinct sensory experiences "brought about by Deaf ways of being" and the use of the eyes for language and discourse (Bahan, 2009). This point is supported by research that shows that the retinas of deaf people develop in a way that allows for enhanced peripheral vision as compared with species-typical hearing people (Codina et al, 2011). Moreover, young deaf children's language and reading development is supported in unique ways that are related to the development of eye gaze, visual attention, and visual phonological processing (Lieberman, 2012;McQuarrie & 16 Abbott, 2013).…”