Structural and functional brain reorganisation due to blindness: The special case of bilateral congenital anophthalmia.

• Bilateral congenital anophthalmia is the absence of the eyes, and means no light can be detected pre- or post-natally. • In humans with anophthalmia, the occipital lobe and superior colliculus respond to auditory input. • Motion area V5/hMT + in people with anophthalmia shows a tonotopic organization. • In human and non-human primates, anophthalmia leads to degeneration of the lateral geniculate nucleus. • We propose that auditory input projects from superior colliculus via the pulvinar to V5/hMT+. Investigating the changes in the brain that result from a loss of sensory input has provided significant insight into the considerable capacity of the brain to reorganise. One of the difficulties in studying sensory-deprived populations is that the time and extent of sensory loss vary significantly. In this review, we consider the changes in the human brain associated with complete absence of visual input resulting from bilateral congenital anophthalmia, in which the eyes fail to develop. We describe the functional reorganisation and associated structural and connectivity changes that occur in the brain of those affected by the condition. By considering animal models of this condition, we investigate the changes that may be occurring on a scale that is not captured by human in vivo imaging techniques. Finally, we lay out a model pathway for taking auditory information to the occipital cortex that may be specific to anophthalmia. [ABSTRACT FROM AUTHOR]