Increased visual cortical thickness in sight-recovery individuals

Abstract

Individuals who are born blind due to dense bilateral cataracts and who later regain vision due to cataract surgery provide a unique model to evaluate the effect of early sensory experience in humans. In recent years, several studies have started to assess the functional consequences of early visual deprivation in these individuals, revealing a number of behavioral impairments in visual and multisensory functions. In contrast, the extent to which a transient period of congenital visual deprivation impacts brain structure has not yet been investigated. The present study investigated this by assessing cortical thickness of occipital areas in a group of six cataract-reversal individuals and a group of six age-matched normally sighted controls. This analysis revealed higher cortical thickness in cataract-reversal individuals in the left calcarine sulcus, in the superior occipital gyrus and in the transverse occipital sulcus bilaterally. In addition, occipital cortical thickness correlated negatively with behavioral performance in an audio-visual task for which visual input was critical, and positively with behavioral performance in auditory tasks. Together, these results underscore the critical role of early sensory experience in shaping brain structure and suggest that increased occipital cortical thickness, while potentially compensatory for auditory sensory processing, might be maladaptive for visual recovery in cases of sight restoration.

Keywords: cortical thickness; sight recovery; visual deprivation.

© 2015 Wiley Periodicals, Inc.

Figures

Figure 1

Regions of interest on the medial surface of the occipital lobe (upper panel) and on the lateral surface of the occipital lobe (lower panel). CUN = cuneus; CAS = calcarine sulcus; LING = lingual gyrus; TOS = transverse occipital sulcus; SOG = superior occipital gyrus; MOG = middle occipital gyrus; IOG = inferior occipital gyrus.

Figure 2

Occipital regions showing a negative correlation between cortical thickness and behavioral performance of cataract‐reversal individuals in the audio‐visual task with low signal‐to‐noise ratio.

Figure 3

Occipital regions showing a positive correlation between cortical thickness and behavioral performance in cataract‐reversal individuals in the auditory tasks.