Scientists are stunned to discover that a ten-year-old German girl’s brain has rewired itself to allow her to see out of one eye as though she has two, even though half of her brain tissue was entirely missing from birth. In a report published this week in the online version of the journal of the Proceedings of the National Academy of Science, Lars Muckli, a neuroscientist at the University of Glasgow, Scotland, said, “Despite lacking one hemisphere, she’s capable of living a normal life.”
The girl, called AH in the study, was born with only one cerebral hemisphere after the right side of her brain stopped developing at seven weeks gestation. She was also missing most of her right eye. Neurological researchers are astonished that an fMRI revealed her retinal ganglion-cells “changed their predetermined crossing pattern” and re-mapped in her brain to create nearly normal bi-scopic vision.
“The human cerebral cortex,” the report says, “contains continuous topographic
maps” that help the person process visual, auditory and other sensory information. “It is believed that these maps result from a self-organizing process that is supported by complex interactions between molecular cues and neuronal activity.” The fact that AH’s vision was nearly normal, “suggested a drastic reorganization” of her sensory or receptor neurons, “from the normal left eye to the intact left hemisphere.”
AH, described by the researchers as a “unique” case, lives a normal life, attending school with other children her own age and participating in sports. She has a history of seizures in early childhood and suffers only a slight weakness on her left side.
Dr. 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.”
Muckli added, “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 discovery may help to rekindle a debate on eugenic abortion that was recently sparked by comments from US Supreme Court Justice Ruth Bader Ginsberg, who said that abortion could help eradicate unwanted sections of the population. “Frankly I had thought that at the time Roe was decided, there was concern about population growth and particularly growth in populations that we don’t want to have too many of,” Ginsburg told Emily Bazelon of the New York Times.
Increasingly abortion, coupled with in-utero diagnosis, is being called into question by disability rights campaigners, who have criticised it as a deadly form of prenatal discrimination.
Most countries that allow abortion include permission to kill a child deemed to be defective in the womb. The legislation in the UK allows abortion “when there is a substantial risk that if the child were born it would suffer from such physical or mental abnormalities as to be seriously handicapped.” In Britain, a diagnosis of possible “abnormalities” – such as those suffered by AH – means the child can be killed without a legal gestational time limit, up to the stage of full development.