Girl Born with Half a Brain is Only Person in World to see Both Fields of Vision Through One Eye

Girl born with half a brain is only person in world to see both fields of vision through one eye



This brain scan show how the youngster's right side of the brain did not develop

A 10-year-old girl born with half a brain has both fields of vision in one eye, scientists said today.

The youngster, from Germany, has the power of both a right and left eye in the single organ in the only known case of its kind in the world.

University of Glasgow researchers used Functional Magnetic Resonance Imaging (fMRI) to reveal how the girl’s brain had rewired itself in order to process information from the right and left visual fields in spite of her not having a whole brain.

The right hemisphere in the girl’s brain failed to develop in the womb.

Visual information is gathered by the retina at the back of the eye and images are inverted when they pass through the lens of the pupil.

Normally the left and right fields of vision are processed and mapped by opposite sides of the brain, but scans on the German girl showed that retinal nerve fibres that should go to the right hemisphere of the brain diverted to the left.

They also found that within the visual cortex of the left hemisphere, which creates an internal map of the right field of vision, ‘islands’ had been formed within it to specifically deal with, and map out, the left visual field in the absence of the right hemisphere.



Doctors believe the girl's brain rewired itself after the right side failed to develop properly in the womb

Lead author Dr Lars Muckli said: 'This study has revealed the surprising flexibility of the brain when it comes to self-organising mechanisms for forming visual maps.

'The brain has amazing plasticity but we were quite astonished to see just how well the single hemisphere of the brain in this girl has adapted to compensate for the missing half.

'Despite lacking one hemisphere, the girl has normal psychological function and is perfectly capable of living a normal and fulfilling life. She is witty, charming and intelligent.'

The girl’s underdeveloped brain was discovered when, aged three, she underwent an MRI scan after suffering seizures of brief involuntary twitching on her left side.

Apart from the seizures, which were successfully treated and slight weakness on her left side (hemiparesis), the girl had a normal developmental and medical history, attending regular school and taking part in activities such as roller-skating.

In other cases, where patients have half of the brain removed (hemispherectomy), to treat severe epilepsy for example, one field of vision is lost in both eyes - i.e. they see only objects on the left or right side of their vision. In the case of the German girl, her left and right field vision is almost perfect in one eye.

The study, which was begun by Dr Muckli at the Max Planck Institute for Brain Research in Germany is published in the ‘Proceedings of the National Academy of Science USA’.

Source