The Prefrontal Cortex – Headquarters of Humanity

Look at your profile in the mirror. Your vertical forehead houses your prefrontal cortex, the most human part of your brain. It distinguishes you from your prehuman ancestors and from other primates living today.

The prefrontal cortex is your judgment seat and thinking cap, where you develop flexible thinking and mental control. It is your personal time machine that integrates the past with the present, and anticipates the future. It balances experience with perception to determine appropriate action.

Your remarkable prefrontal cortex is where wisdom reigns. It gives you the ability to see things from someone else's point of view, to walk in their shoes – in a word, empathy. As religious animals, it is our "vault of heaven."

Vulnerable to Injury
Not only is the prefrontal cortex the last area of the brain to evolve in human beings, it is the last to develop in individuals – and one of the first to lose its function due to generalized stress or injury to the central nervous system. In fact, much of our knowledge of the prefrontal cortex comes from a study of injured brains.

Unlike other areas of the brain, the prefrontal cortex is not particularly plastic. If it is damaged in childhood, moral and social awareness may never develop. Injury to the prefrontal cortex can have devastating effects on one's higher-order executive functions, such as "source memory" and "working memory."

Source Memory
Source memory refers to remembering when or where something happened. Although persons with prefrontal cortex damage can recollect people, events, and facts, they may not be able to recall when the event happened or where they learned the fact.

Their brains cannot access and integrate the diverse aspects of a stored memory. Source memory is one of the slowest types of recall to develop in childhood, and the first to deteriorate with age. (This may be why young children can be so easily led astray by suggestive questioning.)

Working Memory
Working memory is a simple term for the amazingly complex ability of your brain to temporarily hold and simultaneously compare present sense data with past images from its archives. Not just old factoids, these stored memories are reanimated and imbued with the emotions that originally created them.

Working memory performs split-second mind-mapping of its vast neural networks; evaluates the pros and cons of various response options; runs through what-if scenarios; decides on the best course; then orchestrates action. Alternative responses are stored for later recall.

Working memory enables behavior to be guided by ideas, concepts, and plans, rather than solely by environmental conditions that prompt knee-jerk responses. It adds reason to risk-assessment, morality to mind.

Unfortunately, this higher brain function is quite vulnerable to injury. Although many individuals with traumatic brain injury perform well on standard neuropsychological tests, they often exhibit significantly greater deficits on measures of executive function, including an impaired working memory.

Also, in patients with high blood pressure (hypertension) whose working memory was measurably impaired, brain scans showed a decrease in blood flow to the prefrontal (and parietal) region of the brain.

Moral Center
When working memory is damaged, so is reason and comprehension, self-restraint and deliberate foresight. A person reacts to events on impulse. Interpretation is absent or can be irrational, even bizarre. Excessive and inappropriate behavior is the inevitable consequence.

Since the 1980s, scientists have correlated damage to the prefrontal cortex with the inability to make morally and socially acceptable decisions, as well as with psychopathic and violent behavior.

Research suggests that the prefrontal cortex mediates a person's ability to depart temporarily from a main task in order to explore alternative tasks – and then return back to where they left off. Performing several separate tasks consecutively is known as multitasking.

This complex mental juggling comes at a price, however. Researchers measured a 20-30% loss in the total time it took for subjects to complete two separate problems, when they switched back and forth mentally between the tasks. [Journal of Experimental Psychology: Human Perception and Performance, August 2001]

Mastermind of Your Brain
A specific type of multitasking behavior that plays a key role in human cognition is called branching, and depends on the front-most region of the brain, the anterior prefrontal cortex, an area especially well-developed in humans compared to other primates.

Studies suggest that humans may be the only species capable of performing branching, which involves keeping a goal in mind over time (working memory), while at the same time being able to change focus among tasks (attentional resource allocation).