Prefrontal cortex (PFC)

The prefrontal cortex (PFC) is part of the brain that helps regulate decision-making, planning, and speaking. The PFC is part of the frontal lobe—one of the last parts of the brain to develop in humans. The PFC helps regulate emotion and executive function, which includes complicated mental processes such as planning and decision-making. Scientists have been able to study the PFC through imaging and observations of people who have illnesses or injuries that affect that section of the brain. Advances in neuroimaging in the 2020s have improved scientists’ ability to map how the PFC connects with other brain regions, deepening the understanding of its role in behavior and mental health. Scientists believe that the PFC is an important factor in a number of mental illnesses and disorders, such as major depressive disorder, bipolar disorder, and the later stages of Alzheimer’s disease.

Background

The prefrontal cortex is one part of the cerebrum, the largest part of the human brain. The brain acts as the body’s control center, directing the operations of the organs and processes necessary for the body to function. The cerebrum controls functions such as sight, hearing, speech, and motor control. The cerebrum is split into left and right hemispheres, which are further broken down into four lobes—the frontal lobe, the parietal lobe, the occipital lobe, and the temporal lobe. The lobes are separated from each other by grooves (sulci) and fissures. Although they are separate, different parts of the brain work together to perform tasks. Even areas of the brain that are suited to one task generally work with other parts to complete other tasks. Different brain parts can also “learn” to perform different functions if parts of the brain are damaged by injury or illness.

Overview

The prefrontal cortex is part of the brain of mammals. The PFC is well-developed in humans, but it is less developed in animals such as rats, which can make some brain studies challenging in rodents and other animals. The PFC is located directly behind the skull at the front of the forehead. The frontal lobe, of which the PFC is a part, extends from the front of the skull to about the middle of the brain; the PFC is a major section of the frontal lobe. It is itself broken down into different parts, though the exact parts and names are debated among scientists.

The PFC is a vital part of daily life because of its role in cognitive function. The PFC plays a major role in executive function, which is higher-order thinking that includes decision-making and planning for the future. This part of the brain contributes to humans developing and producing speech and also helps in abstract reasoning. People use the PFC to understand others’ emotions and thoughts, making it important for feelings of empathy. It can also give people insight into themselves, their thoughts, and their judgments. Because the PFC regulates so many cognitive functions, an injury or illness that affects that section of the brain can greatly influence vital day-to-day actions.

Scientists have developed a basic understanding of how the PFC works, although they still do not understand the majority of how the brain functions (in terms of the detailed mechanisms and interactions involved). They do know the PFC collects information from other parts of the brain. This information can include visual or auditory information. The PFC uses this input and then sends commands back to other parts of the brain based on the input. For example, the PFC can send signals to control motor function or focus the attention of the senses.

The PFC develops over the early course of a human lifetime and is the last part of the brain to fully develop. This development continues into a person’s twenties. Scientists theorize that this results in young adults and teenagers not always making the best possible decisions or planning for the future. However, adults with a fully developed prefrontal cortex can also face problems if their PFC does not always function at the most efficient level.

Brain arousal also affects the performance of the PFC. For example, a person could experience weak PFC function if they are tired or only partially awake. A person can also be affected by too much brain arousal, such as experiencing a great amount of stress or trauma. Scientists believe this might be one explanation for why people sometimes make poor decisions when they are tired or overly stressed. Scientists believe brains that maintain healthy levels of arousal can create strong neural pathways from the PFC to other parts of the brain. This allows the PFC to better regulate thoughts, actions, and emotions. When a person experiences stress, the PFC’s function weakens, and other parts of the brain are activated. Scientists believe that a weakened PFC could activate the brain’s more primitive parts, such as the amygdala. When a person uses these less developed sections, it can lead to overreactions instead of thoughtful action. Furthermore, if these more primitive parts are overused, the brain will begin to rely on them more often. Studies also link PFC dysfunction to trauma-related disorders such as post-traumatic stress disorder (PTSD), where stress can impair executive control.

Scientists have also found a link between the PFC and common mental illnesses and disorders. For example, depression is a mental illness that can cause sadness, loss of interest, and hopelessness. Imaging studies have shown decreased activity in parts of the PFC in people suffering from depression. Bipolar disorder is a condition that can cause manic and depressive episodes. During manic episodes, people become less inhibited, more active, and more distractible. Imaging studies have shown that the part of the PFC that helps regulate inhibitions has decreased activity during manic episodes. Scientists do not yet fully understand the connections between the PFC and mental illness, but they hope that by studying the PFC, they can someday help people with these disorders.

Bibliography

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