By Thomas H. Maugh II
May 16, 2012, 2:15 p.m.
The tamping rod that blew through Phineas Gage's brain 163 years ago damaged only a small portion of his brain, but it disrupted a much larger proportion of his neural connections, UCLA researchers reported Wednesday. The finding, based on imaging of Gage's skull, may help explain the behavioral changes he endured following the accident.
Phineas P. Gage was a construction supervisor for the Rutland and Burlington Railroad. On Sept. 13, 1848, he was working at a site near Cavendish, Vt. He had drilled a hole in a rock that was to be removed then filled the hole with blasting powder. After instructing an assistant to pour sand on top of the powder to cushion it, he turned away briefly. Unfortunately, the assistant did not follow his directions and when Gage began tamping down the powder with a 13-pound, 3-foot-7-inch iron rod in the next step of the procedure, the powder exploded, shooting the rod clean through his cheek and brain.
The rod was later found 25 feet away, covered with blood and brain tissue. Surprisingly, Gage, then 25, recovered. But his behavior changed abruptly.
No longer an affable young man, he became fitful, irreverent and profane. Unable to retain his railroad job because of the personality changes, he took a succession of somewhat menial jobs, including as a stagecoach driver in South America. He was eventually reunited with his family in San Francisco, where he died of an epileptic seizure 12 years after the fateful accident.
His skull now resides at the Warren Anatomical Museum at Harvard Medical School in Boston. It is too fragile to be imaged again, but UCLA neurologist Jack Van Horn and his colleagues tracked down high-resolution CT images that had been taken at Brigham and Women's Hospital 11 years ago. Those images had been thought to be lost for more than a decade.
The team then imaged the brains of men of about the same size and age as Gage; the men were also all right-handed, like Gage. Using modern computational techniques, the team combined the CT image of Gage's skull with the images of the brains of the modern men to assess what kind of damage had occurred.
They reported in the journal PLoS One that the rod damaged only 4% of Gage's cortex, but that it destroyed about 11% of neural connections in the white matter of the brain. Thus, even though the physical damage was restricted to the left frontal lobe, the damage to the white matter affected neural connections throughout the brain. "Connections were lost between the left frontal, left temporal and right frontal cortices, and the left limbic structures of his brain," Van Horn said, and that "was a major contributor to the behavioral changes he experienced."
Van Horn is a member of UCLA's Laboratory of Neuro Imaging, which is part of an ambitious effort, along with Massachusetts General Hospital and the National Institutes of Health, to map the trillions of microscopic links that connect the brain's 100 billion neurons -- an effort that will produce what is known as a "connectome." Researchers hope that mapping the connectome will lead to new answers about mental disorders related to the breakdown of these links and about damages due to brain injury.