the all-important prefrontal cortex -- 3/16/15
Today's selection --from The Organized Mind by Daniel J. Levitin. The prefrontal cortex is the all-important part of the brain that handles reasoning and implies control, in counterbalance to the emotions and impulses generated in other parts of the brain. It is not fully developed in humans until after the age of twenty:
"We have a more highly developed prefrontal cortex than any other species. It's the seat of many behaviors that we consider distinctly human: logic, analysis, problem solving, exercising good judgment, planning for the future, and decision-making. It is for these reasons that it is often called the central executive, or CEO of the brain. Extensive two-way connections between the prefrontal cortex and virtually every other region of the brain place it in a unique position to schedule, monitor, manage, and manipulate nearly every activity we undertake. Like real CEOs, these cerebral CEOs are highly paid in metabolic currency. Understanding how they work (and exactly how they get paid) can help us to use their time more effectively.
"It's natural to think that because the prefrontal cortex is orchestrating all this activity and thought, it must have massive neural tracts for back-and-forth communication with other brain regions so that it can excite them and bring them on line. In fact, most of the prefrontal cortex's connections to other brain regions are not excitatory; they're the opposite: inhibitory. That's because one of the great achievements of the human prefrontal cortex is that it provides us with impulse control and, consequently, the ability to delay gratification, something that most animals lack. Try dangling a string in front of a cat or throwing a ball in front of a retriever and see if they can sit still. Because the prefrontal cortex doesn't fully develop in humans until after age twenty, impulse control isn't fully developed in adolescents (as many parents of teenagers have observed). It's also why children and adolescents are not especially good at planning or delaying gratification.
"When the prefrontal cortex becomes damaged (such as from disease, injury, or a tumor), it leads to a specific medical condition called dysexecutive syndrome.
"The condition is recognized by the kinds of planning and time coordination deficits that Ruth the homemaker, Ernie the accountant, and Peter the architect suffered from. It is also often accompanied by an utter lack of inhibition across a range of behaviors, particularly in social settings. Patients may blurt out inappropriate remarks, or go on binges of gambling, drinking, or sex with inappropriate partners. And they tend to act on what is right in front of them. If they see someone moving, they have difficulty inhibiting the urge to imitate them; if they see an object, they pick it up and use it.
"What does all this have to do with organizing time? If your inhibitions are reduced, and you tend to do things now that you might regret later, or that make it difficult to properly complete projects you're working on. Binge-watch an entire season of Mad Men instead of working on the Pensky file? Eat a donut (or two) instead of sticking to your diet? That's your prefrontal cortex not doing its job. In addition, damage to the prefrontal cortex causes an inability to effectively go forward or backward in time in one's mind remember Peter the architect's description of starting over and over and not being able to move forward. Dysexecutive syndrome patients often get stuck in the present, doing something over and over again, perseverating, revealing a failure in temporal control. They can be terrible at organizing their calendars and To Do lists due to a double whammy of neural deficits. First, they're unable to place events in the correct temporal order. A patient with severe damage might attempt to bake the cake before having added all the ingredients. And many frontal lobe patients are not aware of their deficit; a loss of insight is associated with these frontal lobe lesions, such that patients generally underestimate their impairment. Having an impairment is bad enough, but if you don't know you have it, you're liable to go headlong into situations without taking proper precautions, and end up in trouble.
"As if that weren't enough, advanced prefrontal cortex damage interferes with the ability to make connections and associations between disparate thoughts and concepts, resulting in a loss of creativity. The prefrontal cortex is especially important for generating creative acts in art and music. This is the region of the brain that is most active when creative artists are functioning at their peak.
"If you're interested in seeing what it's like to have prefrontal cortex damage, there's a simple, reversible way: Get drunk. Alcohol interferes with the ability of prefrontal cortex neurons to communicate with one another, by disrupting dopamine receptors and blocking a particular kind of neuron called an NMDA receptor, mimicking the damage we see in frontal lobe patients. Heavy drinkers also experience the frontal lobe system double whammy: They may lose certain capabilities, such as impulse control or motor coordination or the ability to drive safely, but they aren't aware that they've lost them -- or simply don't care -- so they forge ahead anyway."