What do psychopaths, people with ADHD, schizophrenics, people with borderline personality disorder, alcoholics, and people addicted to cocaine, opiates, or heroin have in common?

1. An unfortunate lack of self-control or empathy, often costly to themselves and to society.

2. An unfortunate lack of gray matter in their brain's "control center," the prefrontal cortex.

Behind your forehead sits a part of the brain called the prefrontal cortex (PFC), which makes you an empathetic and rational person. It is nicknamed the "CEO of the brain," because it is responsible for planning, decision-making, organization, regulating emotions and impulse control. For instance, if you have problems with procrastination, you can blame a failure of your PFC to overcome your brain's emotional reward system.

The PFC's claim to fame is being the part that teenage brains have not developed yet, even though 95 percent of the teenage brain has been fully grown since age six. Incomplete PFC development is why teenagers have such a bad reputation, making them struggle more than other people do with narcissism and impulsiveness.

More importantly, the PFC is responsible for keeping aggressive impulses in check, which is why some have called in the brain's "guardian angel." So when people have poor PFC functioning, it can cause much much more serious problems:

"[M]urderers showed significantly poorer functioning of the prefrontal cortex ... Reduced prefrontal functioning can result in a loss of the ability of this part of the brain to control … aggressive feelings. Prefrontal damage also encourages risk-taking, irresponsibility, rule breaking, emotional and aggressive outbursts, and argumentative behavior that can also predispose to violent criminal acts. Loss of self-control, immaturity, lack of tact, inability to modify and inhibit behavior appropriately, and poor social judgment could predispose to violence as well. This loss of intellectual flexibility and problem-solving skills, and reduced ability to use information provided by verbal cues can impair social skills essential for formulating nonaggressive solutions to fractious encounters. Poor reasoning ability and divergent thinking that results from prefrontal damage can lead to school failure, unemployment, and economic deprivation, thereby predisposing to a criminal and violent way of life."

People with denser PFCs are better at understanding others' feelings and perspectives, a trait known as "cognitive empathy." As I described last August, a small brain is the reason you can't love everyone. Perhaps I should have been more specific back then: a small PFCis the main reason you can't love everyone, since those with small PFCs cannot maintain large social networks. People with bigger PFCs are more socially competent — they are better at understanding and predicting others' behavior.

Damage to the PFC impairs social, moral and harm judgment, as shown by the story of railroad worker Phineas Gage. In 1848, a tamping iron flew up through his jaw and out the top of his head. He survived, but the tamping iron changed his personality by damaging his PFC. After the incident he "uttered 'the grossest profanity' and showed 'little deference for his fellows.'"

The link from PFC function to self-control has been experimentally confirmed in modern times. Using magnetic stimulation to enhance the PFC can reduce cravings for nicotine and cocaine, while using magnetic stimulation to disrupt the PFC can cause risk-taking behavior and prevent good reputation-building abilities. Scientists are currently looking into magnetic PFC stimulation as a way to treat drug addiction.

Having a big, dense, healthy PFC generally makes you better at life — better at doing any given task, resisting temptation and being understanding to others. The reverse is also true: those who are generally poor at life have smaller, less dense, unhealthy PFCs.

The potential for any medical treatment or device that can enhance this part of the brain cannot be overstated. It could be used to help rehabilitate criminals, addicts and the mentally ill. It could be used to enhance the performance of people in almost any kind of work, from nurses and salespeople to researchers and politicians. It could be used for personal character improvement. Arguably, it could be taken even further, since most societal problems can be attributed to people either acting impulsively or not caring enough about others.

Some people might be unwilling to alter or improve their bodies using technology, with objections along the lines of "It wouldn't be natural" or "Trying to 'fix' people would take away their free will." But the brain always tries to alter and improve itself by adapting to new situations. There is no such thing as an unaltered brain. The "unnatural" objection can be dismissed because "natural" does not mean "good" in any sense of the word. Finally, the "free will" objection backfires completely: because your PFC is responsible for self-control, increasing its capabilities would give you more free will.

While all of this lofty description would be useless if enhancing the PFC is unethical, impossible, dangerous or even simply impractical, there are plenty of feasible methods to enhance the PFC. They could become widely available with enough demand to motivate development of the technology.

Increasing the neural activity and gray matter volume of the prefrontal cortex — by using vitamin supplements, prescription medicine, electrical or magnetic stimulation, gene therapy, genetic modification or anything else that would work — would improve people by increasing their self-control and cognitive empathy.

The next articles in this series will explore a few of the different ways to practically implement this idea.