Post date: May 21, 2012 2:37:50 PM
A case of brain damage that occured 164 years ago is yielding new insights for scientists trying to establish how white matter engages with the rest of the brain to affect behaviour. Phineas Gage was a 25 year old railway worker who gained sudden fame for surviving an accident that blew a three and half foot long metal spike though his head.
While he lived to tell the tail, friends and family said his personality was permanently changed.
ANIMATION (LABORATORY OF NEURO IMAGING (LONI), UCLA HANDOUT - Phineas Gage's ghastly accident in 1848 is a source of fascination for neuroscientists, which is why a team at the University of California, Los Angeles (UCLA) has imaged the unfortunate Mr Gage's skull and recreated the impact of the accident, as a tool for research.
In findings published in the journal, PLoS one, the team says they computationally simulated the passage of the iron through Gage's skull on the basis of reported and observed skull damage to assess the extent of damage to cortical gray and white matter damage.
Because Gage's delicate skull is nearly two centuries old, it's unlikely to be imaged again.
John Van Horn, assistant professor of neurology at UCLA says the last known hi-resolution scans were lost about 10 years ago, until the UCLA team recovered them. They then took 110 brain images of right-handed males who were about the same size, ethnicity and age as Gage and built a model to compare their healthy brains to a reconstructed image of Gage's damaged one.
"We were able to mathematically fit that data into his skull," Van Horn said. "And then estimate the white matter fiber pathways using data from diffusion weighted imaging, which is a method for mapping white matter fiber in the living brain. By doing that mapping we were able to then say, 'What would that look like if it were intact? What would it look like if it had a tamping iron injury? And what would the network level effects of that be?'"
Van Horn says Phineas Gage is probably the most famous neuroscience case in neurological history.
The 25-year-old railroad foreman was laying track in Vermont when a 13-pound iron tamping rod used to pack explosive powder into a hole blasted through his cheek and out of the top of his head. The spike was found 25 feet away covering with brain tissue and blood but Gage managed to live for an additional 11 years before dying after a series of convulsions.
Dr. John Harlow treated Gage for a few months following his accident and reportedly said his personality changed for the worst. Gage, who was once friendly and affable prior to the accident, could not immediately hold down a stable job and turned "different after this injury," said Van Horn.
"According to Dr. Harlow, he was profane and irresponsible," Van Horn said. "Many people have used this fact to explain the importance of the frontal lobe."
For 164 years since the railroad worker's accident, scientists attributed his behavior change to a damaged cerebral cortex. Approximately four percent of his cortex was pierced by the rod. But by using brain-imaging data, the researchers at UCLA discovered that nearly 11 percent of Gage's white matter was damaged, which they say more likely explains his changed personality.
"White matter connects and conveys the signals between the different brain areas," Van Horn said. "And while he may have cortical damage, those brain areas also connect through a very diffuse set of pathways that connect those frontal lobes and those areas that were damaged to the rest of the brain, indicating that the potential damage was much more widespread than people had previously believed."
Scientists discovered that the loss of Gage's white matter was similar to scans of patients that had degenerative brain diseases.
"Understanding the pattern and connectivity of the brain can help us understand and develop cures for things like Alzheimer's disease, Multiple Sclerosis, Parkinson's disease, Huntington's disease, as well as other degenerative disorders of the brain," Van Horn said.
The team reported that "while considerable damage was, indeed, localized to the left frontal cortex, the impact on measures of network connectedness between directly affected and other brain areas was profound, widespread, and a probable contributor to both the reported acute as well as long-term behavioral changes."
Although Gage's emotional traits changed, he was eventually able to travel and secure a job as a stagecoach driver for many years, leaving many experts wondering about the regenerative functions of the brain.
Gage's skull and 43-inch-long tamping rod is on display in Warren Anatomical Museum at Harvard Medical School.