The frontal lobe is the home of much of what makes us human. It plays a role in everything from movement to intelligence, helps us anticipate the consequences of our actions, and aids in the planning of future actions. This part of the brain is the newest from an evolutionary perspective, and is the last to develop, making the frontal lobe both highly malleable and susceptible to developmental damage.
Where is the Frontal Lobe Located?
Neuroscientists have traditionally divided the brain's cerebrum into four lobes: the frontal, parietal, occipital, and temporal. The cerebrum is the newest part of the brain to have evolved, and houses most “higher” functions, such as conscious thought, morality, memory, and the ability to learn through memorization, deduction, and other complex processes. The frontal lobe plays a key role in this complex set of cognitive functions.
Named for its location, the frontal lobe is situated toward the front of the cerebrum, just behind the forehead and under the frontal skull bones. It sits atop the temporal lobe, in front of the parietal lobe, and apart from the occipital lobe, with portions of the limbic system—sometimes called the limbic lobe crossing all four brain lobes, including the frontal lobe.
The central sulcus separates the frontal and parietal lobes, with the lateral sulcus separating the frontal and temporal lobes.
What Does the Frontal Lobe Do?
The frontal lobe is the slowest part of the brain to mature, continuing to create and prune neural connections until a person's mid-twenties. This means that brain damage early in life renders the frontal lobe particularly vulnerable, potentially affecting behavior and cognition forever.
The frontal lobe is involved in a wide range of “higher” cognitive functions. Although all mammals have a frontal lobe, highly social mammals, such as dolphins and primates, tend to have more developed frontal lobes. This suggests that our social interactions may play a key role in the development of intelligence, and that the brain must devote significant resources to responding to the demands of social interactions. Humans have larger and more developed frontal lobes than any other animal.
Some of the many functions of the frontal lobe include:
- Coordinating voluntary movements, such as walking and reaching for objects. The frontal lobe is home to the primary motor cortex.
- Assessing future consequences of current actions. Thus the frontal lobe plays a vital role in impulse control, including decisions about when to spend money and eat, and whether a particular decision is morally or socially acceptable.
- Assessing similarities and differences between two objects.
- Formation and retention of long-term memories, particularly emotional memories derived from the limbic system.
- Language: The frontal lobe plays a role in understanding language, linguistic memories, and speaking.
- Emotional expression and regulation, in addition to understanding the emotions of others; empathy may derive from the frontal lobe.
- The development of personality. Because of the frontal lobe's roles in memory, emotional regulation, expression, impulse control, and other key functions, it plays a key role in personality. Damage to the frontal lobe can spur sudden and immediate alterations in personality.
- Managing reward. Dopamine, a neurotransmitter that plays a role in reward and motivation, is heavily active in the frontal lobe because most of the brain's dopamine-sensitive neurons located here.
- Attention regulation, including selective attention. Frontal lobe difficulties can lead to executive functioning issues, as well as disorders such as ADHD.
What Are Some Important Structures in the Frontal Lobe?
Most neuroscientists divide the frontal lobe into four distinct regions, each containing a number of vital structures. Those include:
- Medial frontal lobe: This region contains the cingulate gyrus, which is a part of the limbic system. It also contains the superior frontal gyrus, which research suggests plays a role in self-awareness.
- Lateral frontal lobe: This region contains the superior frontal gyrus, which aids in self-awareness, as well as the middle frontal and inferior frontal gyrus. The inferior frontal gyrus plays a role in language processing.
- Polar region: This region is home to the frontomarginal gyrus, as well as the transverse frontopolar gyri.
- The orbital frontal lobe contains a number of structures, including the anterior orbital gyrus, medial orbital gyrus, posterior orbital gyrus, and gyrus rectus. The orbital gyri is connected to the vagus nerve, an important part of the limbic system that coordinates and controls emotional and automatic reactions.
How Does the Frontal Lobe Interact With Other Areas of the Body?
Though the frontal lobe is often deemed the seat of consciousness, it cannot think or feel alone. No single brain region can fully control any other region or function without heavy input from the body, other parts of the brain, and the outside world. The frontal lobe is no exception, and works alongside all other brain lobes to coordinate consciousness.
The frontal lobe, like all brain regions, connects with the limbic lobe, which houses brain structures associated with the limbic system. The limbic system controls automatic and primitive reactions, but these reactions are heavily dependent upon emotion and experience. Because the frontal lobe is home to much consciousness, its input into the limbic lobe is vital. For instance, an emotional reaction to a traumatic experience can affect limbic functioning forever, and the memories housed in the frontal lobe may strengthen limbic system reactions over time.
Because the frontal lobe is home to many higher functions, it is especially dependent upon experiences and memories. That means that social interactions, education, and similar experiences heavily affect the functioning of this important brain region. Sensory input also plays a key role, since the frontal lobe relies on memory, previous experience, and information about the surrounding world to judge the potential effects of future actions.
What Happens when The Frontal Lobe is Damaged?
Most people experience some atrophy in the frontal lobe in their senior years, with frontal lobe volume decreasing by .5%-1% each year beginning around age 60. This slow and steady decline accounts for many of the changes, such as mild memory loss and difficulty with finding some words, associated with normal aging. More rapid frontal lobe decline can lead to symptoms of dementia.
The frontal lobe is highly vulnerable to damage for at least two reasons: first, as the last brain region to fully develop, developmental anomalies—including child abuse, an insufficiently stimulating environment, drug use, infections, and other factors—can permanently alter its development. Second, the frontal lobe's home in the front of the forehead renders it highly vulnerable, especially to auto accident-related injuries, violence, and falls. Even relatively minor blows can rattle the brain sufficiently to impede frontal lobe functioning.
The effect of frontal lobe damage is dependent on its location and severity, as well as how quickly it is detected. Children who face serious abuse may live with frontal lobe damage for years, while car accident survivors often get more immediate help. Treatment for frontal lobe injuries typically includes medical and psychological treatment, since the frontal lobe houses the emotional life and personality.
Overall health, age at the time of injury, quality of medical treatment, and an active and stimulating environment can all affect recovery trajectories. Seniors are more vulnerable to frontal lobe damage because their frontal lobes are already deteriorating. Likewise, people living in unstimulating environments, or who do not regularly “exercise” their brains may experience more rapid deterioration and only minimal improvement.
Frontal lobe damage can have extensive and far-reaching damage, as in the case of frontal lobe dementia, which leads to aggression, behavior changes, and difficulties with language. Some other consequences of frontal lobe damage include:
- Inability to engage immoral decision-making.
- Difficulties with planning, executive functioning, and attention.
- Loss of memory.
- Sudden and dramatic changes in personality.
- Declining intelligence.
- Changes in emotions, including signs of depression and anxiety.
- Difficulty understanding social cues or relating to the emotions of other people.
- Changes in motor skills and spatial reasoning abilities.
- A range of specific syndromes. One such syndrome, reduplicative paramnesia, causes a person to believe that is or her home is actually a precise replica of another location.
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