The frontal lobe is part of the cerebral cortex of the brain. Individually, the paired lobes are known as the left and right frontal cortex.
As the name implies, the frontal lobe is located near the front of the head, under the frontal bones of the skull and near the forehead. It was the last region of the brain to evolve, making it a relatively new addition to the structure.
All mammals have a frontal lobe, although the size and complexity vary by species. Most research suggests that primates have larger frontal lobes than many other mammals.
The two sides of the brain largely control operations on opposite sides of the body. The frontal lobe is no exception.
Thus, the left frontal lobe affects muscles on the right side of the body. Similarly, the right frontal lobe controls the muscles on the left side of the body. This may determine how the body is affected by a brain injury.
The brain is a complex organ, with billions of cells called neurons working together. Much of what these neurons do and how they work is not fully understood.
The frontal lobe works together with other brain regions to control the overall functioning of the brain. Memory formation, for example, depends on sensory information, which in turn depends on numerous areas of the brain. It is therefore a mistake to attribute a brain function to a single region.
Moreover, the brain can be “rewired” to compensate for an injury. This does not mean that the frontal lobe can recover from all injuries, but that other regions of the brain can change in response to frontal lobe injury.
The frontal lobes are the largest lobes of the human brain and are also the most commonly injured region in traumatic brain injury
Regions or parts of the frontal lobe
Primary Motor Cortex or Area
The primary motor cortex (M1, Brodmann’s area 4) is located in the precentral gyrus just rostral to the central sulcus
It is the source of cortical neurons that will project to the brainstem and spinal cord to activate neurons involved in the control of voluntary movements
It receives information from the primary somatosensory area (S1, in the postcentral gyrus
) and premotor cortex, as well as from the ventral ventral nucleus of the thalamus (a relay nucleus with projections from the cerebellum)
These inputs modulate the output of M1 by providing information on position, timing and coordination
of voluntary movements. The output of M1 passes through the internal capsule
to synapse in the brainstem (the projection called the corticobulbar tract)
or the spinal cord (the corticospinal tract)
Damage to M1 results in contralateral contralateral motor motor deficits, initially a flaccid hemiplegia/hemiparesis and later a spastic hemiplegia/hemiparesis.
Depending on the extent of cortical damage, these deficits may
be localized to a specific region of the body or may be more generalized.
The premotor cortex is located immediately rostral to M1. Its main function is to assist in the integration of sensory and motor information for the performance of an action (praxis)
Therefore, it receives information from the secondary area (immediately caudal to S1 in the parietal cortex) and from the anterior thalamic nucleus (a relay nucleus with projections from the basal ganglia, which in turn are a group of subcortical nuclei that modulate motor activity)
Output from the premotor cortex is to M1 and the contralateral premotor area (via the corpus
Damage to the premotor cortex can result in apraxia, an inability to perform skilled actions that could previously be performed (but without paralysis); deficits in contralateral fine motor control, such as performing complex serial movements; and difficulty using sensory feedback for control and movement performance.
Dorsolateral Prefrontal Cortex
The dorsolateral prefrontal cortex is located in the convexity of the prefrontal cortex, superior to the orbital frontal cortex and anterior to the premotor cortex
The dorsolateral prefrontal cortex has been found to be involved in the superordinate control functions of various cognitive tasks, such as decision making, novelty detection, working memory, conflict management, mood regulation, theory-of-mind processing, and timing
The orbitofrontal cortex (OFC) is the area of the prefrontal cortex that lies just above the orbits (also known as eye sockets). It is therefore located in the most frontal part of the brain and has extensive connections to sensory areas and limbic system structures related to emotion and memory.
The orbitofrontal cortex is a little-known area of the brain, but one that also inspires great interest for some of the functions it is supposed to play in higher-order cognition, such as decision making
In fact, the prefrontal cortex and the frontal lobes in general are considered essential for rational thinking, reasoning, and even full personality expression
Thus, much of the research on the COF has focused on functions that seem especially important for the thought processes that separate humans from other species with “lesser” cognitive abilities. However, we know very little for certain about the orbitofrontal cortex, and the extent to which the functions attributed to it below are actually regulated by the COF is still debated.
What are the functions of the frontal lobe?
The frontal lobe plays a key role in planning for the future, including self-management and decision making.
People with frontal lobe damage often have difficulty gathering information, remembering past experiences, and making decisions based on this information.
Some of the many other roles the frontal lobe plays in everyday functions include
- Speech and language production: Broca’s area, a region of the frontal lobe, helps convert thoughts into words. Damage to this area can impair the ability to speak, understand language or produce meaningful speech.
- Some motor skills: The frontal lobe houses the primary motor cortex, which helps coordinate voluntary movements, such as walking and running.
- Object comparison: The frontal lobe helps categorize and classify objects, as well as distinguish one item from another.
- Memory formation: Virtually every region of the brain plays a role in memory, so the frontal lobe is not alone. However, research suggests that it plays a key role in the formation of long-term memories.
- Understanding and reacting to the feelings of others: The frontal lobe is vital for empathy.
- Personality formation: The complex interplay between impulse control, memory and other tasks helps shape a person’s key characteristics. Damage to the frontal lobe can radically alter personality.
- Reward-seeking behavior and motivation: Most of the brain’s dopamine-sensitive neurons are in the frontal lobe. Dopamine is a brain chemical that contributes to feelings of reward and motivation.
- Attention management, including selective attention: When the frontal lobe cannot properly manage attention, disorders such as attention deficit disorder (ADHD) can occur.
what kind of lesions can occur in the frontal lobe?
Damage to the frontal lobe is usually caused by stroke or trauma. It can also be caused by a degenerative disease, which is a disease that gets worse over time.
There are other less common conditions that can also affect the frontal lobe.
Traumatic brain injury
Because of its location, the frontal lobe is especially prone to damage when head trauma occurs
The injury can be penetrating, such as a gunshot wound, or non-penetrating, such as a blow to the head in a traffic accident.
Traumatic brain injuries vary in severity. Many people recover from traumatic brain injuries in a matter of days, and the most severe forms can cause permanent brain injury or even death.
Strokes can also damage the frontal lobe. When blood flow to the frontal lobe is interrupted, there is a loss of function in that part of the brain. This can also occur as a result of bleeding in the brain.
Vascular dementia can occur after several small strokes. It is the most common cause of frontal lobe impairment. Vascular dementia has been linked to Alzheimer’s disease and other degenerative brain disorders
Dementia is a term used to describe conditions that cause memory loss and other problems with thinking and reasoning.
Frontotemporal dementia (FTD) is a group of disorders affecting the frontal and temporal lobes. FTD is the second most common cause of dementia in people under the age of 65.
People with FTD often have changes in behavior and personality. They may also have problems with language.
People with a type of Alzheimer’s disease called frontal variant Alzheimer’s disease may have similar symptoms. This form of Alzheimer’s disease is sometimes misdiagnosed as FTD.
Possible Consequences of Frontal Lobe Lesions
One of the most infamous frontal lobe injuries occurred to railroad worker Phineas Gage.
Gage survived after a railroad spike pierced a portion of his frontal lobe. Although Gage survived, he lost his eye and much of his personality.
Gage’s personality changed drastically, and the once mild-mannered worker struggled to follow even the simplest of plans. He became aggressive in speech and behavior and had little impulse control.
Much of what we know about the frontal lobe comes from Gage’s case reports. However, these have since been questioned. Little is known for sure about Gage’s personality before his accident, and many stories about him may be exaggerated or untrue.
The case demonstrates a broader point about the brain, and that is that our understanding of it is constantly evolving. Therefore, it is not possible to accurately predict the outcome of a given frontal lobe injury, and similar injuries may evolve very differently in different people.
However, in general, frontal lobe damage due to a blow to the head, stroke, tumors, and disease can cause the following symptoms:
- Loss of simple movement of various parts of the body(Paralysis)
- Inability to plan a sequence of complex movements needed to complete multi-step tasks, such as making a cup of coffee(Sequencing)
- Loss of spontaneity in interacting with others (Sequencing)
- Inability to express language(Broca’s Aphasia)
- Loss of flexibility in thinking and persistence of a single idea or behavior(Perseveration)
- Inability to concentrate on a task and filter out distractions (Attention)
- Mood fluctuations(Emotional lability)
- Difficulty solving problems
- Difficulty inhibiting or controlling a response or impulse(Disinhibition)
- Decreased motivation, initiation and persistence in activities(Adynamia)
- Decreased awareness/perception of difficulties
- Changes in social behavior
- Personality changes
how is a frontal injury or damage diagnosed?
Healthcare professionals can diagnose frontal lobe strokes and infections with diagnostic scans. The options are magnetic resonance imaging (MRI) and computed tomography (CT or CAT).
An MRI creates a two- or three-dimensional image of the brain using a magnetic field and radio waves. A CT scan creates a three-dimensional image from multiple x-rays.
Some causes, such as dementia or traumatic brain injury, may show up on a scan as atrophy, or loss of brain tissue. It is also possible for the scan to show nothing.
Both MRI and CT scans are effective tools for diagnosing vascular dementia.
A comprehensive neuropsychological evaluation or a concussion test can help a healthcare professional assess frontal lobe damage. These tests examine
- Speech skills
- Motor skills
- Social behavior
- Impulse control
- Problem solving
Treatment of frontal lobe damage
Treatment of frontal lobe injuries focuses on first addressing the cause of the injury. The doctor may prescribe medications to treat an infection, surgery to remove a tumor, or medications to reduce the risk of stroke.
Depending on the cause of the injury, lifestyle remedies may also help. For example, frontal lobe damage after a stroke may mean switching to a healthier diet and more exercise to reduce the risk of a future stroke.
Once the initial cause of the injury is addressed, treatment focuses on helping the person regain as much function as possible.
Sometimes, the brain can learn to work around an injury as other regions compensate for frontal lobe damage. Occupational therapy, speech and physical therapy can advance this process
These treatments can be especially helpful in the early stages of recovery, as the brain begins to heal.
Frontal lobe damage can affect personality, emotions and behavior. Individual, couple and family counseling can help manage these changes.
Medications for impulse control can also be helpful, especially for people who have problems with attention and motivation.
Treatment of frontal lobe damage is often varied and requires ongoing attention and continual reassessment of treatment strategy. It may include speech and occupational therapists, physicians, psychotherapists, neurologists, imaging specialists and other professionals.
Recovery from a frontal injury is often a long process. Breakthroughs can occur suddenly or infrequently and are impossible to predict completely. Recovery is closely linked to supportive care, regular cognitive challenges and a lifestyle that supports good health.