The Brain & Decision making

In 1848, Phineas Gage, a railroad worker in Vermont, suffered a bizarre acci- dent: He was using an iron bar to pack gunpowder down into a hole drilled into a rock that had to be blasted to clear a roadbed for the railroad. The pow- der unexpectedly exploded and sent the iron bar flying through his head before landing 80 feet away.  (Damasio, Grabowski, Frank, Galabruda, & Damasio,
1994). The bar managed to miss any vital areas and spared most of his brain but tore through the center of the very front of the brain—a region called the ventromedial
prefrontal cortex. Amazingly, he not only survived, he was even able to talk and walk away from the accident after being unconscious for a few minutes. His recovery was difficult, largely because of infections, but he eventually was able to hold jobs such as a coach driver. Henry Jacob Bigelow, a professor of sur- gery at Harvard University, declared him “quite recovered in faculties of body and mind” (Macmillan, 2000). Based on such a report, one might have thought that this part of the brain performed no function.
However, all was not well. His personality had undergone major changes. Before his injury he had been polite, respect- ful, popular, and reliable, and generally displayed the ideal behavior for an American man of that time.1 Afterward he became just the opposite—as his own physician, Harlow, later described him:
Brain Structures fitful, irreverent, indulging at times in the grossest profanity (which was not previously his custom), mani- festing but little deference for his fellows, impatient of restraint or advice when it conflicts with his desires, at times pertinaciously obstinate, yet capricious and vacillating, devising many plans of future operations, which are no sooner arranged than they are abandoned in turn for others appearing more feasible. A child in his intellectual capacity and manifesta- tions, he has the animal passions of a strong man. Previous to his injury, although untrained in the schools, he possessed a well- balanced mind, and was looked upon by those who knew him as a shrewd, smart businessman, very energetic and persistent in executing all his plans of operation. In this regard his mind was radically changed, so decidedly that his friends and acquaintances said he was “no longer Gage.” (Harlow, 1868, p. 327)

Gage is the classic case demonstrating the importance of the ventrome- dial prefrontal cortex to human personality. Subsequently, a number of other patients with similar damage have been described, and they all show the same sorts of personality disorders. Family members and friends will describe them with phrases like “socially incompetent,” “decides against his best interest,” and “doesn’t learn from his mistakes” (Sanfey, Hastie, Colvin, & Grafman, 2003).  In general, it is thought that the more medial portion of the anterior prefrontal region, where Gage’s injury was localized, is important to motivation, emotional regulation, and social sensitivity (Gilbert, Spengler, Simons, Frith, & Burgess, 2006).
■ The ventromedial prefrontal cortex plays an important role in achieving the motivational balance and social sensitivity that is key to making successful judgments.