Sunday, May 21, 2017

Phineas Gage revisited

It took an explosion and 13 pounds of iron to usher in the modern era of neuroscience.

In 1848, a 25-year-old railroad worker named Phineas Gage was blowing up rocks to clear the way for a new rail line in Cavendish, Vt. He would drill a hole, place an explosive charge, then pack in sand using a 13-pound metal bar known as a tamping iron.

But in this instance, the metal bar created a spark that touched off the charge. That, in turn, "drove this tamping iron up and out of the hole, through his left cheek, behind his eye socket, and out of the top of his head," says Jack Van Horn, an associate professor of neurology at the Keck School of Medicine at the University of Southern California.

Gage didn't die. But the tamping iron destroyed much of his brain's left frontal lobe, and Gage's once even-tempered personality changed dramatically.

"He is fitful, irreverent, indulging at times in the grossest profanity, which was not previously his custom," wrote John Martyn Harlow, the physician who treated Gage after the accident.

This sudden personality transformation is why Gage shows up in so many medical textbooks, says Malcolm Macmillan, an honorary professor at the Melbourne School of Psychological Sciences and the author of An Odd Kind of Fame: Stories of Phineas Gage.

"He was the first case where you could say fairly definitely that injury to the brain produced some kind of change in personality," Macmillan says.

And that was a big deal in the mid-1800s, when the brain's purpose and inner workings were largely a mystery. At the time, phrenologists were still assessing people's personalities by measuring bumps on their skull.

Gage's famous case would help establish brain science as a field, says Allan Ropper, a neurologist at Harvard Medical School and Brigham and Women's Hospital.

"If you talk about hard core neurology and the relationship between structural damage to the brain and particular changes in behavior, this is ground zero," Ropper says. It was an ideal case because "it's one region [of the brain], it's really obvious, and the changes in personality were stunning."

So, perhaps it's not surprising that every generation of brain scientists seems compelled to revisit Gage's case.

For example:

In the 1940s, a famous neurologist named Stanley Cobb diagrammed the skull in an effort to determine the exact path of the tamping iron.

In the 1980s, scientists repeated the exercise using CT scans.

In the 1990s, researchers applied 3-D computer modeling to the problem.

And, in 2012, Van Horn led a team that combined CT scans of Gage's skull with MRI scans of typical brains to show how the wiring of Gage's brain could have been affected.


Two renderings of Gage's skull show the likely path of the iron rod and the nerve fibers that were probably damaged as it passed through. Van Horn JD, Irimia A, Torgerson CM, Chambers MC, Kikinis R, et al./Wikimedia

"Neuroscientists like to always go back and say, 'we're relating our work in the present day to these older famous cases which really defined the field,' " Van Horn says….

There is something about Gage that most people don't know, Macmillan says. "That personality change, which undoubtedly occurred, did not last much longer than about two to three years."

Gage went on to work as a long-distance stagecoach driver in Chile, a job that required considerable planning skills and focus, Macmillan says.

This chapter of Gage's life offers a powerful message for present day patients, he says. "Even in cases of massive brain damage and massive incapacity, rehabilitation is always possible."

Gage lived for a dozen years after his accident. But ultimately, the brain damage he'd sustained probably led to his death.

He died on May 21, 1860, of an epileptic seizure that was almost certainly related to his brain injury.

http://www.mprnews.org/story/2017/05/21/why-brain-scientists-are-still-obsessed-with-the-curious-case-of-phineas-gage

Courtesy of a colleague

1 comment:

  1. Van Horn JD, Irimia A, Torgerson CM, Chambers MC, Kikinis R, Toga AW. Mapping connectivity damage in the case of Phineas Gage. PLoS One. 2012;7(5):e37454.

    Abstract
    White matter (WM) mapping of the human brain using neuroimaging techniques has gained considerable interest in the neuroscience community. Using diffusion weighted (DWI) and magnetic resonance imaging (MRI), WM fiber pathways between brain regions may be systematically assessed to make inferences concerning their role in normal brain function, influence on behavior, as well as concerning the consequences of network-level brain damage. In this paper, we investigate the detailed connectomics in a noted example of severe traumatic brain injury (TBI) which has proved important to and controversial in the history of neuroscience. We model the WM damage in the notable case of Phineas P. Gage, in whom a “tamping iron” was accidentally shot through his skull and brain, resulting in profound behavioral changes. The specific effects of this injury on Mr. Gage's WM connectivity have not previously been considered in detail. Using computed tomography (CT) image data of the Gage skull in conjunction with modern anatomical MRI and diffusion imaging data obtained in contemporary right handed male subjects (aged 25–36), we computationally simulate the passage of the iron through the skull on the basis of reported and observed skull fiducial landmarks and assess the extent of cortical gray matter (GM) and WM damage. Specifically, we find 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. Yet, while significantly affecting several likely network hubs, damage to Mr. Gage's WM network may not have been more severe than expected from that of a similarly sized “average” brain lesion. These results provide new insight into the remarkable brain injury experienced by this noteworthy patient.

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