FRONTAL LOBE: LOCATION, ANATOMY AND FUNCTIONS - NEUROPSYCHOLOGY - 2025

The frontal lobe is the largest lobe of the four that exist in the brain of mammals. It is located in the front part of each brain hemisphere and controls important cognitive functions, such as emotional expression, memory, problem solving, language, impulse control, social and sexual behavior, spontaneity or muscle control. The left frontal lobe affects the muscles on the right side of the body, and the right frontal lobe controls the muscles on the left side of the body.

The frontal lobe is the brain area that most distinguishes us humans from other animals. For this reason, it has aroused special interest in researchers, who have carried out multiple studies on its functions and its operating mechanism.

Frontal lobe

This region is widely related to functions as important as language, control of motor actions and executive functions, so that, if injured, the person can suffer serious problems that we will also talk about in this article.

Location

The brain is made up of cortical areas and subcortical structures. The cerebral cortex is divided into lobes, separated by furrows, the most recognized are the frontal, the parietal, the temporal and the occipital, although some authors postulate that there is also the limbic lobe.

The cortex is divided into two hemispheres, the right and the left, so that the lobes are present symmetrically in both hemispheres, with a right and a left frontal lobe, a left and right parietal lobe, and so on..

The cerebral hemispheres are divided by the interhemispheric fissure while the lobes are separated by different sulci.

Image adapted from: Blausen.com staff. «Blausen gallery 2014». Wikiversity Journal of Medicine. DOI: 10.15347 / wjm / 2014.010. ISSN 20018762. (Own work), via Wikimedia Commons

The frontal lobe reaches from the most anterior part of the brain to the Rolando fissure (or central fissure) where the parietal lobe begins and, on the sides, to the Silvio fissure (or lateral fissure) that separates it from the temporal lobe.

Anatomy

Regarding the anatomy of the human frontal lobe, it can be said that it is very voluminous and has a pyramid shape. It can be divided into precentral and prefrontal cortex:

Precentral cortex

It is the association zone, it is composed of the dorsolateral, ventrolateral and orbitofrontal cortex, and its functions are related to the executive system, such as the control and management of executive functions.

Image adapted from: NEUROtiker (Own work), via Wikimedia Commons

Frontal lobe connections

The frontal lobe, and especially the prefrontal cortex, is the cortical area most widely connected to the rest of the brain. The main connections are as follows:

-Front cortico-cortical connections

Receive and send information to the rest of the lobes. The most important are the frontotemporal connections, which are related to audioverbal activity, and the frontoparietal ones, related to the control and regulation of cutaneous-kinesthetic sensitivity and pain.

-Cortico-subcortical frontal connections

• Centrolateral thalamic nuclei that connect with the precentral cortex.
• Dorsomedial thalamic nucleus that connects with the prefrontal cortex, related in some way to memory.
• Anterior ventral thalamic nucleus that connects with the frontal limbic cortex (cingulate area).

Fronto-limbic connections

They facilitate emotional and affective regulation through neuroendocrine and neurochemical secretions.

Fronto-basal circuits

In these circuits some sections of the frontal lobe are connected with the striatum, the globus pallidus and the thalamus:

• Motor circuit, related to the control of movements.
• Oculomotor circuit, related to the association between our movements and the position of objects identified through sight.
• Dorsolateral prefrontal circuit, related to executive functions.
• Cingulate prefrontal circuit, related to emotional responses.

It could be said that the frontal lobe receives inputs from the areas responsible for sensory processing of information and sends outputs to the areas responsible for giving a response, especially motor ones.

The prefrontal cortex

The prefrontal cortex is the last area to develop in the frontal lobe and the brain in general. This area is especially important because it fulfills functions without which we would not be effective in our day-to-day lives, such as planning and organizing future behaviors.

It is shaped like a pyramid, like the frontal lobe, and has an inner, outer, and inner face. Regarding the connections established with the rest of the structures, there are three main circuits:

Dorsolateral prefrontal circuit

It goes to the dorso-lateral area of ​​the caudate nucleus. From here it connects with the dorso-medial globe pallidus and with the substantia nigra. These project to the dorso-medial and ventral-anterior thalamic nuclei, and from there they return to the prefrontal cortex.

Orbitofrontal circuit

It projects to the ventromedial caudate nucleus, then to the globe pallidus and the ventro-medial substantia nigra, from there it passes to the ventral-anterior and dorso-medial thalamic nuclei and finally returns to the prefrontal cortex.

Anterior cingulate circuit

It projects to the ventral striatum, it has connections with the globe pallidus, the ventral tegmental area, the habenula, the hypothalamus, and the amygdala. Finally it returns to the prefrontal cortex.

This area is attributed the functions of structuring, organizing and planning behavior. The patient experiences the following faults if this area is injured:

• Selective capacity failures.
• Failures in sustained activity.
• Deficits in associative capacity or in the formation of concepts.
• Deficits in planning capacity.

Frontal lobe functions

The frontal lobe fulfills multiple functions that can be summarized as:

Executive functions

• Virtual simulation of the behavior to be carried out through previous experiences and vicarious learning.
• Setting a goal and the steps to follow to complete it.
• Planning, coordination and implementation of the necessary behaviors to achieve the objective.
• Maintenance of the objectives throughout the entire process until reaching the goal. Here working memory and sustained attention are involved.
• Inhibition of the rest of the stimuli that have nothing to do with the goal and that may interfere with them.
• Coordination of all the systems necessary to perform the necessary actions, such as sensory, cognitive and behavioral.
• Analysis of the results obtained and, if necessary, modification of behavior patterns based on these results.

Social functions

• Inference of the intentions and thinking of others. This ability is called the theory of mind.
• Reflection on our knowledge and interests and the ability to communicate them.

Emotional functions

• Control of reinforcing stimuli to motivate us to carry out the behaviors and cognitive processes that we must carry out.
• Regulation of impulses.
• Awareness of emotions.

Motor functions

• Sequencing, coordination and execution of motor behaviors.

Linguistic functions

• Ability to understand the language of others and produce our own.

Executive functions will be described in greater depth below due to their great importance in humans.

Executive functions

Executive functions could be defined as the last step in the control, regulation and direction of human behavior. This concept first emerged from the hand of AR Luria in 1966 in his book Higher Cortical Function in Man.

Lezak popularized this term in American psychology. This author highlights the difference between executive and cognitive functions, stating that, although cognitive functions suffer damage if executive functions function correctly, the person will continue to be independent, constructively self-sufficient and productive.

Executive functions are made up of four components:

Goal formulation

It is the process by which needs are determined, what is wanted and what is capable of getting what is wanted. If a person has this function altered, they cannot think about what to do and have difficulties in starting activities.

These alterations can occur without the need for brain damage, simply with a poor organization in the prefrontal lobe.

Planning

It is responsible for determining and organizing the steps necessary to carry out an intention.

This process requires certain capacities such as: conceptualizing changes in present circumstances, seeing herself developed in the environment, seeing the environment objectively, capable of conceiving alternatives, making choices and developing a structure to carry out the plan.

Implementation of plans

It is interpreted as the action of initiating, maintaining, changing and for sequences of complex behaviors in a comprehensive and orderly manner.

Effective execution

It is the assessment based on the objectives and the resources used to achieve those objectives.

The teaching system is very important for the correct configuration of executive functions, since these functions begin to develop in childhood, from the first year of life, and do not mature until puberty or even later.

Executive functions are mainly related to the prefrontal cortex, but some studies performed with PET (positron emission tomography) indicate that, when the activity becomes routine, another part of the brain takes over in the activity to free the patient. prefrontal cortex and that it can take care of other functions.

Evaluation of executive functioning

The most used techniques for evaluating the executive system are:

• Wisconsin Card Sorting Test. Test in which the patient has to classify a series of cards in various ways, using a different category each time. Failures in this test would imply problems in the formation of concepts that could be due to lesions in the left frontal lobe.
• The tower of Hanoi-Seville. This test is used to examine complex problem solving skills.
• Maze tests. These tests provide data on higher levels of brain function that require planning and foresight.
• Construction toys. These are unstructured tests and are used to assess executive functions.

Frontal lobe dysfunctions

The frontal lobe can be damaged as a result of trauma, heart attacks, tumors, infections or due to the development of some disorders such as neurodegenerative or developmental disorders.

The consequences of frontal lobe damage will depend on the area damaged and the extent of the injury. The syndrome, due to damage to the frontal lobe, best known is the prefrontal syndrome that will be described below.

Prefrontal Syndrome: Phineas Cage

The first well-documented description of a case of this syndrome was that made by Harlow (1868) about the case of Phineas Gage, over time this case has continued to be studied and today it is one of the best known in the field. of psychology (cited in León-Carrión & Barroso, 1997).

Phineas gage

Phineas was working on a train track when he had an accident while compacting gunpowder with an iron bar. It seems that a spark reached the gunpowder and it exploded, throwing the iron bar directly at his head. Phineas suffered an injury to the left frontal lobe (specifically in the medial orbital region) but was still alive, although he had sequelae.

The most significant changes due to the injury she suffered were increased impulses, inability to control herself, and difficulties planning and organizing.

People with an injured prefrontal cortex present changes in personality, motor skills, attention, language, memory, and executive functions.

Personality changes

According to Ardila (cited in León-Carrión & Barroso, 1997) there are two ways or aspects to describe the changes in personality caused by this syndrome:

1. Changes in activation for action. Patients tend to feel apathy and disinterest, therefore, they do everything reluctantly and are not very proactive.
2. Changes in the type of response. The response given by the patient is not adaptive, it does not correspond to the stimulus that is presented to him. For example, they may have a test and start choosing clothes to wear for too long instead of studying.

Changes in motor skills

Among the changes in motor skills we can find:

• Neonatal reflexes. It seems as if the patients regress and regain the reflexes that babies have and they are lost with development. The most common are:
  • Babinski reflex. Tonic dorsal extension of the big toe.
  • Grip reflex. Close the palm of the hand when something touches it.
  • Suction reflex.
  • Palmomental reflex. Touching the palm of the hand triggers movements in the chin.
• Repeat the examiner's actions.
• They overreact to stimuli.
• Disruption of behavior.
• Repeat the same movement over and over.

Changes in attention

The main changes occur in the orientation response, patients have deficits to orient themselves to the stimuli that they should at home and when following the examiner's instructions.

Language changes

The most characteristic are:

• Transcortical motor aphasia. The language is very limited and is reduced to short sentences.
• Subvocal language. Changes in the speech apparatus, probably due to aphasia, such that the person pronounces strangely.
• Commission of naming errors, such as persevering and responding before fragments of the stimulus and not the stimulus in general.
• They respond better to visual than verbal stimuli because they have poor control of behavior through language.
• They cannot keep a central topic of conversation.
• Lack of connecting elements to give forms and make the language logical.
• Concretism. They give specific information without putting it in context, which can make it difficult for the other person to understand.

Changes in memory

The frontal lobes play an important role in memory, especially in short-term memory. Patients with frontal lobe injuries have problems with memory storage and retention. The most frequent alterations are:

• Temporal organization of memory. Patients have trouble ordering events in time.
• Amnesias, especially for injuries produced in the orbital area.

Changes in executive functions

Executive functions are the most impaired in patients with frontal injuries, since for their correct performance a complex elaboration and the integration and coordination of various components are necessary.

People with frontal syndrome are unable to form a goal, plan, carry out actions in an orderly manner and analyze the results obtained. These deficits prevent them from leading a normal life since they interfere with their work / school, family, social tasks…

Although the symptoms described are the most common, their characteristics are not universal and will depend on both patient variables (age, premorbid performance…), and the injury (specific location, magnitude…) and the course of the syndrome.

-Typical syndromes

The category of frontal syndromes is very broad and encompasses another series of syndromes that differ according to the injured area. Cummings (1985), describes three syndromes (cited in León-Carrión & Barroso, 1997):

1. Orbitofrontal syndrome (or disinhibition). It is characterized by disinhibition, impulsiveness, emotional lability, poor judgment, and distractibility.
2. Frontal convexity syndrome (or apathetic). It is characterized by apathy, indifference, psychomotor retardation, loss of drive, abstraction, and poor categorization.
3. Mid-frontal (or akinetic) syndrome of the frontal lobe. It is characterized by paucity of spontaneous gestures and movements, weakness and loss of sensation in the extremities.

Imbriano (1983) adds two more syndromes to the classification elaborated by Cummings (cited in León-Carrión & Barroso, 1997):

1. Polar syndrome. Produced by injuries in the orbital area. It is characterized by alterations in intellectual capacity, spatial-temporal disorientation, and lack of self-control.
2. Splenial syndrome. Produced by left medial injuries. Characterized by alterations in affective facial expressions and affective indifference, thought disorders and language alterations.

References

1. Carmona, S., & Moreno, A. (2014). Executive control, decision making, reasoning and problem solving. In D. Redolar, Cognitive Neuroscience (pp. 719-746). Madrid: Médica Panamericana SA
2. León-Carrión, J., & Barroso, J. (1997). Neuropsychology of Thought. Seville: KRONOS.
3. Redolar, D. (2014). Frontal lobes and their connections. In D. Redolar, Cognitive Neuroscience (pp. 95-101). Madrid: Médica Panamericana SA