Frontal Brain Lobe and Its Function

If there is a single brain part that is responsible both for emotions and judgment, it is the frontal brain lobe. Likewise, it affects our personality, intelligence, behavior, and self-awareness.

The frontal brain lobe is the center for planning, speaking, body movement control, as well as problem-solving. Interestingly, it is the center that enables us to write and concentrate (1). 

In this article, we will elaborate on the frontal brain lobe. Namely, we will discuss its position, anatomy, functions, and structure. Finally, we will address the conditions resulting from the frontal brain lobe damage and diseases. 

Position of the Frontal Brain Lobe 

First of all, the frontal brain lobe is the largest part of our brain. Secondly, as its name implies, it is positioned in the front of the head. More importantly, the frontal lobe is positioned in both hemispheres.

Its anatomical position implies that it spreads from central sulcus to the front pole. This brain part contains four frontal curves. Those are:

• Precentral curve, 
• Upper curve, 
• Middle curve, 
• Lower curve (2). 

Most noteworthy, this brain part contains the Broca's fields. This segment of the frontal brain lobe represents the primary motor cortex. Besides, they contain the Motor Speech Component. The frontal lobe also houses a center for controlling the willing horizontal orientation of a look to the opposite side.

A very important part of the frontal lobe is the prefrontal cortex. It has a role in planning and executing motor activities, taking initiative, motivation, control of emotions, and behavior. The cortical urinary center is located in this lobe. The inflow of blood into the frontal lobe is made possible by the anterior and middle cerebral arteries. 

Functions of the Frontal Lobe

The frontal lobes are responsible for planning and executing learned and conscious actions. Moreover, the frontal lobe is the location of many inhibitory functions. There are at least 4 functionally distinct areas in the frontal lobes: 

• the primary motor cortex in the precentral gyrus (located most posteriorly), 
• the medial areas, 
• the orbital areas, 
• the lateral areas (prefrontal areas).

The medial frontal area is responsible for awareness and motivation. The frontal orbital area helps shape social behavior. The inferolateral area is responsible for linguistic functions, while the dorsolateral area manages freshly acquired information. Therefore, it is functionally called "working memory". 

The primary motor cortex controls all voluntary movements of the contralateral side of the body (each part of the body is projected into the primary motor cortex in the form of a strictly defined spatial map).

Since 90% of the fibers from the primary motor cortex cross the medial line in the area of the brain stem, damage to the motor cortex of one lobe causes weakness of the contralateral side of the body. Besides, specific parts of the frontal lobe house the smell recognition centers.  

Diseases and Conditions Related to the Frontal Brain Lobe

One of the first conditions we will address is depression. Today, we know with certainty that one of the main characteristics of virtually all depressed persons - regardless of the underlying cause of depression - is a significant decrease in blood flow to the frontal lobe and its impaired activity.

This reduced activity is found in the most prominent part of the frontal lobe. It is called the "prefrontal cortex". It is the part of the brain that truly represents the control center of the brain.

However, it is much more than that. We know that the prefrontal cortex is responsible for behavioral planning, decision making, emotional control, self-awareness, and independence from other people.

Depression can be caused by a stroke in the medial part of the frontal lobe. The consequences of these strokes include emotional instability. Generally speaking, depression is not caused by strokes in other parts of the brain.  

Moreover, frontal brain lobe damage can result from surgical removal, injury, or stroke. It can also be a consequence of Alzheimer's disease. Regardless of the process that damages the frontal lobe, the consequences are generally the same.

Patients suffering from Alzheimer's disease who had frontal lobe damage were significantly more depressed. They were also much more likely to have other behavioral problems such as anxiety, self-delusions, and lack of self-discipline.

Patients with major damage to the frontal part of the brain parenchyma extending to the anterior frontal pole sometimes become involuntarily apathetic, unwilling to take any action, and have a noticeably slow response. Patients with impairments in the orbital frontal region may become emotionally labile, insensitive to the effects of their actions, or both.

They can also change their behavior when it comes to expressing euphoria, humor, even vulgarity, as well as become insensitive to social etiquette (3). Mutual acute damage to this prefrontal area can cause intense pain, restlessness and social dysfunction in patients.

With aging, and especially in various forms of dementia, degeneration of the frontal lobes leads to disinhibition and inappropriate behavior.

Damage to the inferolateral area (Broca's area) causes motor aphasia (impaired learning and expression. Lesions of the dorsolateral frontal area may reduce the ability to retain information and process it in real-time (e.g. spelling words backward, distinguishing numbers, and letters consecutively). 

Frontal Lobe Syndrome - Symptoms

Damage to the primary motor cortex causes monoplegia or hemiplegia of the opposite half of the body (4). Enhanced muscle tone is present, while the reflexes are enhanced. Pathological reflexes such as the Babinsky sign are also noted.

Trauma to the complementary motor cortex causes poor spontaneous movement and apraxia. Due to the intersection of the motor paths, these changes are present on the contralateral side of the body. When it comes to the auxiliary motor cortex, the frontal lobe syndrome is also characterized by difficulties in initiating bodily movements.

Conclusion

The frontal brain lobe is located just behind one's forehead. It is the biggest cortex lobe. We can say that the frontal lobe is the brain control center. It plays an important role in problem-solving, planning, impulse control, reasoning, as well as controlling emotions, and behavior.

References

1. Collins A, Koechlin E. Reasoning, learning, and creativity: frontal lobe function and human decision-making. PLoS Biol. 2012;10(3):e1001293. doi: 10.1371/journal.pbio.1001293. Epub 2012 Mar 27. PMID: 22479152; PMCID: PMC3313946.  Found online at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3313946/
2. Hoffmann M. The human frontal lobes and frontal network systems: an evolutionary, clinical, and treatment perspective. ISRN Neurol. 2013;2013:892459. doi: 10.1155/2013/892459. Epub 2013 Mar 14. PMID: 23577266; PMCID: PMC3612492. Found online at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3612492/
3. Séguin JR. The frontal lobe and aggression. Eur J Dev Psychol. 2009 Jan 5;6(1):100-119. doi: 10.1080/17405620701669871. PMID: 24976846; PMCID: PMC4072650.  Found online at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4072650/
4. Pirau L, Lui F. Frontal Lobe Syndrome. [Updated 2018 Dec 19]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019 Jan-. Found online at: https://www.ncbi.nlm.nih.gov/books/NBK532981/