In 1845, an iron rod pierced railroad construction foreman Phineas Gage's brain, changing neuroscience forever. Now, more than 150 years later, neuroscientists have created a diagram of Gage's brain, figuring out just which connections were changed by his accident.
For those not familiar with the story of Gage, he was working on the construction of the Rutland & Burlington Railroad in Vermont, tamping blasting power with a large iron rod. When the powder exploded, the rod shot through Gage's skull, severely damaging his frontal lobe. After the accident, Gage experienced an extreme personality transformation, becoming vulgar, obstinate, and capricious. He no longer remembered many of his friends and lost any concept of the value of money. The incident inspired many early neuroscience researchers to investigate the link between the structure of the brain and personality.
Although Gage's brain tissue is long gone, researchers still have access to his skull, and in 2004, a team of researchers digitally reconstructed the rod's path through Gage's brain. A team of researchers at UCLA's Laboratory of Neuroimaging (LONI), led by Jack Van Horn, reinvestigated that data and then took it a few steps further. The study sought to recreate Gage's connectome, a map of the neural connections in his brain.
After examining structural MRI and DTI data from 110 healthy men aged 25 and 36 (Gage was 25 at the time of his accident and 36 when he died), the researchers created a generalized map of the long-range connections in a healthy human brain. The connectogram at the left displays a healthy human brain, based on averaged data from the 110 men.
Then reexamining data on the trajectory of the rod through Gage's skull, Van Horn's team estimated how much of Gage's cerebral cortex and frontal lobe were destroyed, and from there looked at which long-range connections would be severed based on such a tissue loss. This connectogram offers a rough estimate of which of Gage's neural connections were severed. The researchers believe the connections in grey were destroyed entirely, while the connections in brown were partially severed by the rod.
Although researchers can't determine with complete accuracy the extent of Gage's tissue damage, this study may offer some clue as to the relationship between Gage's physical damage and his neurological changes. In the future, the Human Connectome Project hopes to apply similar techniques to patients whose brains are still very much with us.
You can read the entire paper at PLoS One.