The spatial arrangement of our visual world is conserved in our early visual cortex. That is, the early visual cortex has a specific retinotopic arrangement, whereby stimuli located near each other in the visual field are also represented near each other in the cortex. There are some further specificities to this mapping, for example, the left visual field is represented in the right hemisphere and vice versa. However, this retinotopic arrangement can be modified or reorganised to compensate for developmental alterations. We were fortunate to have the opportunity to work with a patient who was born with only one cerebral hemisphere, and study how such reorganisation occurs. During embryonic gestation, the development of the patient’s right cerebral hemisphere terminated, leading to a loss of the right hemisphere at birth. The patient’s left hemisphere developed maps of the contralateral (right) visual hemifield and, surprisingly, also maps of the ipsilateral (left) visual hemifield. This reveals the remarkable plasticity of the developmental mechanisms in early vision compensating for the missing hemisphere.
Muckli L, Naumer MJ, Singer W. (2009). Bilateral visual field maps in a patient with only one hemisphere. Proceedings of the National Academy of Sciences USA, 106, 13034-9.