Monday, January 8, 2007

A Tamping Iron, Phineas Gage and Genetically Modified Food

A careful reading of this story* about Phineas Gage may explain why some are nervous about accepting genetically modified food. What seems to be just fine on first investigation . . . may just not be. [a Longwoods comment.]

Until fairly recently, scientists thought it was not much good at all, because people whose frontal lobes were damaged seemed to do pretty well without them. Phineas Gage was a foreman for the Ruthland Railroad who, on a lovely autumn day in 1848, ignited a small explosion in the vicinity of his feet, launching a three-and-a-half-foot-long iron rod into the air, which Phineas cleverly caught with his face. The rod entered just beneath his left cheek and exited through the top of his skull, boring a tunnel through his cranium and taking a good chunk of frontal lobe with it. Phineas was knocked to the ground, where he lay for a few minutes. Then, to everyone’s astonishment, he stood up and asked if a coworker might escort him to the doctor, insisting all the while that he didn’t need a ride and could walk by himself, thank you. The doctor cleaned some dirt from his wound, a coworker cleaned some brain from the rod, and in a relatively short while, Phineas and his rod were back about the same business.10 His personality took a decided turn for the worse – and that fact is the source of his fame to this day – but the more striking thing about Phineas was just how normal he otherwise was. Had the rod made hamburger of another brain part – the visual cortex, Broca’s area, the brain stem – then Phineas might have died, gone blind, lost the ability to speak, or spent the rest of his life doing a convincing impression of a cabbage. Instead, for the next twelve years, he lives, saw, spoke, worked, and traveled so uncabbagely that neurologists could only conclude that the frontal lobe did little for a fellow that he couldn’t get along nicely without.11 As on neurologist wrote in 1884, “Ever since the occurrence of the famous American crowbar case it has been known that the destruction of these lobes does not necessarily give rise to any symptoms.”12

But the neurologist was wrong. In the nineteenth century, knowledge of brain function was based largely on the observation of people who, like Phineas Gage, were the unfortunate subjects of one of nature’s occasional and inexact neurological experiments. In the twentieth century, surgeons picked up where nature left off and began to do more precise experiments whose results painted a very different picture of frontal lobe function. In the 1930’s, a Portuguese physician named António Egas Moniz was looking for a way to quiet his highly agitated psychotic patients when he heard about a new surgical procedure called frontal lobotomy, which involved the chemical or mechanical destruction of part of the frontal lobe. This procedure had been performed on monkeys, who were normally quite angry when their food was withheld, but who reacted to such indignities with unruffled patience after experiencing the operation. Egas Moniz tried the procedure on his human patients and found that it has a similar calming effect. (It also had the calming effect of winning Egas Moniz the Nobel Prize for Medicine in 1949.)

Over the next few decades, surgical techniques were improved (the procedure could be performed under local anesthesia with an ice pick) and unwanted side effects (such as lowered intelligence and bed wetting) were diminished. The destruction of some part of the frontal lobe became a standard treatment for cases of anxiety and depression that resisted other forms of therapy.13 Contrary to the conventional medical wisdom and the previous century, the frontal lobe did make a difference. The difference was that some folks seemed better off without it.
But while some surgeons were touting the benefits of frontal lobe damage, others were noticing the costs. Although patients with frontal lobe damage often performed well on standard intelligence tests, memory tests, and the like, they showed severe impairments on any test – even the very simplest test –that involved planning. For instance, when given a maze or a puzzle whose solution required that they consider an entire series of moves before making their first move, these otherwise intelligent people were stumped.14 Their planning deficits were not limited to the laboratory. These patients might function reasonably well in ordinary situations, drinking tea with out spilling and making small talk about drapes, but they found it practically impossible to say what they would do later that afternoon. In summarizing scientific knowledge on this topic, a prominent scientist concluded: “No prefrontal symptom has been reported more consistently than the inability to plan….They symptom appears unique to dysfunction of the prefrontal cortex…[and] is not associated with clinical damage to any other neural structure.”15
Now, this pair of observations – that damage to certain parts of the frontal lobe can make people feel calm but that it can also leave them unable to plan – seem to converge on a single conclusion. What is the conceptual tie that binds anxiety and planning? Both, of course, are intimately connected to thinking about the future. We feel anxiety when we anticipate that something bad will happen, and we plan by imagining how our actions will unfold over time. Planning requires that we peer into our futures, and anxiety is one of reactions that we may have when we do.16 The fact that damage to the frontal lobe impairs planning and anxiety so uniquely and precisely suggests that the frontal lobe is the critical piece of cerebral machinery that allows normal, modern human adults to project themselves into the future. Without it we are trapped in the moment, unable to imagine tomorrow and hence unworried about what it may bring. As scientists now recognize, the frontal lobe “empowers healthy human adults with the capacity to consider the self’s extended existence throughout time.”17 As such, people whose frontal lobe is damaged are described by those who study them as being “bound to present stimuli,”18 or “locked into immediate space and tme,”19 or as displaying a “tendency toward temporal concreteness.”20 In other words, like candy guys and tree climbers, they live in a world without later.

*Excerpt from the book “Stumbling on Happiness” by Daniel Gilbert
Published by Random House of Canada ( 2006