by
Abstract
Accidental damage to the brain's frontal lobe has provided important clues about the region's specialized functions. Researchers recently gathered to commemorate one historic case and to discuss what today's patients reveal about the workings of the brain.
An accidental lobotomy might seem a strange thing to celebrate. But on September 12 and 13, neuroscientists and psychologists gathered in the small town of Cavendish, Vermont to commemorate the 150th anniversary of Phineas Gage losing a chunk of his brain to a flying tamping iron - an accident that helped point scientists toward the realization that the brain's frontal lobes regulate our personality and behavior.
The weekend symposium on frontal lobe function - organized by Malcolm Macmillan of Deakin University in Victoria, Australia - drew researchers from around the world to discuss how the Gage case influenced the debate over whether the brain has localized function, with different regions controlling different activities. Between sessions, participants journeyed to the town square, where they ate homemade apple crisps and viewed Gage's skull and the infamous tamping iron, which had been transported by limousine from Harvard Medical School.
Although Gage is gone, the localization debate still lives - only now the battleground has shifted to the frontal cortex itself. Does the frontal cortex function as a unit, or are its duties subdivided? To address that question, researchers at the conference described their work with "modern-day Gages" - individuals with frontal lobe damage who continue to provide clues about how that brain region regulates our emotions and social conduct.
Tamping and Purging
The sun was shining and the air was crisp as we walked along the railroad tracks, kicking up stones and the occasional hunk of coal, on our way to the site where Phineas met his fate. On September 13, 1848, Gage and his crew were cutting through rock to clear a path for the Rutland and Burlington Railroad. One afternoon, when Gage was packing some blasting powder into the rock, a spark from his tamping iron accidentally ignited the explosive. The blast sent the three-and-a-half foot rod through his left cheek and out the top of his head.
Gage was knocked flat and the tamping iron landed some 20 to 30 yards behind him. It's unclear whether Gage even lost consciousness, but he was soon on his feet. With the help of his crew, Gage climbed into the back of a wagon that carried him the three-quarters of a mile back to the tavern where he was staying. It was there that Gage was doctored by John Harlow.
Harlow was the local physician who treated - and later wrote about - Phineas Gage. According to Fred Barker, a neurosurgeon at Boston General Hospital, Harlow cleaned the wound, removing small bone chips and slivers and replacing some of the larger hunks of bone that had been dislocated by the passage of the tamping iron, which was a full 1.25
inches in diameter at its widest point. He closed the wound with adhesive straps and covered the opening with a wet compress and a nightcap.
Then, in accordance with the standard protocols of the 19th century, Gage was treated to a two-week course of bleeding and purging. For the first few days he was in good shape - aside from the therapeutic vomiting and diarrhea. But the wound became infected and Gage lapsed into a coma. His family ordered the coffin.
But Gage didn't die. On the contrary, Harlow treated the infection and the patient regained consciousness, eventually making a full physical recovery.
Of Two Minds
Gage survived the accident, but his personality did not. Once quiet, respectful, and mentally well-balanced, Gage became "gross, profane, and vulgar to such a degree that his society was intolerable to decent people," wrote the editors of the American Phrenological Journal.
This description, however, wasn't published until 1851 - three years after Gage's encounter with the tamping iron. And Harlow didn't fully disclose Gage's mental deficits until 1868, at which time the physician noted that Gage's personality had changed so radically that his friends said he was "no longer Gage." "Why Harlow waited 20 years to report the 'mental manifestations' of Gage's accident initially "is a bit of a mystery," says Macmillan.
The timing of Harlow's full report is important. Now, we think of Gage as a poster child for localization of brain function, because when he lost part of his frontal cortex, he specifically lost his social inhibitions. At the time of the accident, however, scientists who believed that the brain lacked localized functions considered Gage's physical recovery as proof that one brain region could readily fill in for another. After all, according to Harlow, Gage not only walked away from the accident, but he fully regained his health.
Then, in the 1850s and 1860s, other researchers who were examining patients with specific brain lesions began to report that certain functions were localized. Paul Broca found that the brain region that controlled speech was located in a particular area in the frontal cortex. And John Hughlings Jackson and David Ferrier located the motor cortex. So when Harlow published a detailed description of Gage's loss of intellectual integrity, the neuroscience community was primed to accept this as further evidence of localization.
Lumpers versus Splitters
But Gage did not fully lay to rest the localization debate. Today, neuroscientists still argue about how functions are parceled out within individual brain regions. The frontal cortex alone takes up 30 percent of the brain and regulates everything from memory to motor control, says Art Shimamura of the University of California at Berkeley. But does the frontal
cortex operate as a unit?
The debate is a battle between the "lumpers" and the "splitters," says Shimamura. And the truth most likely falls someplace in the middle. Although the frontal lobes help to control overall behavior, Shimamura's work with patients suggests that the cortex consists of individual neural networks that independently monitor mental functions including memory, movement, and emotion. Thus the frontal cortex may behave more like a democratic board of directors than a domineering CEO, says Shimamura.
Today's Gage
These days, not too many people show up in the clinic complaining of tamping-iron-induced brain damage. However, many men - and it is usually men - sustain frontal lobe damage following alcohol-related accidents: crashing their motorcycles into telephone poles or falling off of balconies during parties. Their later mental deficits are the modern-day equivalents of the inappropriate social behaviors that were ascribed to Gage. One patient with a post-traumatic penchant for barroom brawls - described at the meeting by Bob Knight of the University of California at Berkeley - saw nothing wrong with asking a woman to marry him on their second date.
How can a frontal lobe lesion lead to such a loss of propriety? It's literally a lack of inhibition, says Shimamura. Patients with damage to the frontal cortex lack the ability to inhibit a behavior, particularly once it has been initiated. For example, these patients can draw circles. And they can draw squares. But when they're asked to alternate between the two, Shimamura finds they run into trouble and can produce only one or the other. It's as if, once the subjects are in the circle-drawing mode, they can't stop and switch to another task. Perhaps, similarly, when a person with frontal lobe dysfunction becomes stimulated, he (or she) cannot control behaviors that might be considered aggressive or flirtatious.
Examining these patients using a combination of psychological tests and souped-up neuroimaging techniques will further reveal how different regions within the frontal cortex work together to set our social compass and keep us from misbehaving.
Karen Hopkin, a freelance writer and editor, received her Ph.D. in biochemistry from the Albert Einstein College of Medicine in 1992. She is the creator of the Studmuffins of Science Calendar.
Caleb Brown is an illustrator and biologist living in Montana. By day he drives a delivery van, and by night he draws pictures with his computer.
Phineas Gage: Into the Mind - a 1995 Discover magazine describing the accident and modern-day attempts to pinpoint the exact portions of Gage's brain that were destroyed.
Phineas Gage - differing accounts of Gage's treatment, written by Malcolm Macmillan, the symposium organizer.
Brain Injury Provides Strong Evidence for Mind's Language Machinery - describes how another injury has furthered researchers' understanding of the brain's function.
RETICULUM: Neuroscience History Resources - includes links to online images and exhibits. A part of the Neuroscience History Archives maintained by the Brain Research Institute at UCLA.