The frontal lobe is part of the cerebral cortex, it was the last region of the brain to evolve, so it is a relatively new addition. All mammals have a frontal lobe, although the size and complexity varies depending on the species. Most research suggests that primates have larger frontal lobes than many other mammals (Reber & Tranel, 2019).
The frontal lobes
Traditional classification systems divide the frontal lobes into the precentral cortex (the strip immediately anterior to the central sulcus or Rolandic fissure) and the prefrontal cortex (which extends from the frontal poles to the precentral cortex and includes the frontal operculum). The latter is further divided into: orbitofrontal cortex (including the orbitobasal or ventromedial and inferior mesial regions), ventrolateral prefrontal cortex, dorsolateral prefrontal cortex, medial prefrontal cortex (which contains the anterior cingulate gyrus and the preliminary and infralimbic cortices) and caudal prefrontal cortex, which includes the frontal eye fields (Zanto & Gazzaley, 2019).
Each of these areas has widespread connectivity and is characterized by its different functions, including its intervention in different cognitive processes such as: memory, language, attention, abstraction, executive, motor, social, emotional functions and inhibition of basic responses in the search for a more complex objective (Pressman & Rosen, 2015). According to Deright (2019), its importance lies in the execution of decision making and executive control, that is, the selection and coordination of behaviors.
Various studies have shown that the frontal lobes are extremely vulnerable to injury due to their location at the front of the skull, proximity to the sphenoid wing, and their large size. MRI studies have shown that the frontal area is the most common region of injury after mild or moderate head trauma (Levin et al., 1987 cited by Chow, 2000).
Clinically, they have been used to describe disorders of the frontal lobes and their extended networks such as: frontal lobe syndromes, frontal network syndromes, frontal systems syndromes, executive dysfunction and metacognition, although not all are synonymous and the Terms differ depending on the authors or researchers (Garrard et al., 2002; Goldberg, 2002; Hoffmann & Schmitt, 2004; Karussis et al., 2000; Kumral et al., 1999; Malm et al., 1998; Neau et al. ., 2000; Tarkka, 2001; Tullberg et al., 2004).
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According to Hoffmann (2013), strictly speaking, frontal network syndromes constitute the most precise neurobiological representation. The term, frontal network syndromes (FNS), emphasizes the universal connectivity of the frontal lobes with all other regions of the brain. For example, the stroke literature is replete with FNS that have been reported with discrete lesions outside the anatomical boundary of the frontal lobe, such as subcortical gray matter, subcortical white matter, with isolated lesions of the brainstem, cerebellum, temporal and parietal lobes.
Among the most studied frontal network syndromes are: impairment of working memory, executive function, avolition, disinhibition and emotional lack of control. In addition, a number of secondary manifestations can be identified, such as a wide range of behavioral abnormalities, including: loss of social norms, imitative behavior, compulsions and obsessions (W. Chow & Cummings, 2009; Hoffmann , 2013a).
However, due to its anatomy and importance, studies of the frontal lobe have not only focused on frontal network syndromes, but also on alterations associated with classical cognitive functions attributed to prefrontal regions (Markowitsch et al., 1979). ; Pressman & Rosen, 2015).
Motion control
Among these classic cognitive functions are those related to the control of movement, which is implemented at many levels including the spinal cord, cerebellum, and basal ganglia. However, there are three main cortical brain regions involved in this function: the primary motor cortex (PMC), the premotor cortex (preMC), and the motor areas of the medial frontal lobe, which include the presupplementary motor area (preSMA), the supplementary motor area (SMA) and adjacent motor areas in the cingulate sulcus (Pressman & Rosen, 2015).
For this reason, a lesion of the frontal lobe, including the prefrontal cortex (PFC), can cause the appearance of a motor disorder known as apraxia, which is associated with the inability to perform an expert motor activity despite intact strength, sensation, attention, memory and impulse, without interference from other movement disorders such as dystonia, tremor or chorea. Patients with apraxia may describe a loss of the ability to manipulate commonly used tools, or to do something more complex, such as sewing or knitting. Apraxia is not a well-localized disorder, and different types of lesions can cause it, including parietal, frontal, and subcortical lesions. It is almost always associated with lesions in the left hemisphere or corpus callosum, and has been described specifically in the context of median frontal motor and premotor cortex lesions. Apraxia often occurs in patients with neurodegenerative disorders, in which predominantly the parietal lobes are affected, such as Alzheimer’s disease, or the frontal lobes in corticobasal degenerations (Heilman, 2010; Pressman & Rosen, 2015). .
Attention
Another of the most investigated classic processes in recent decades has been , due to its complexity and connection with many cortical and subcortical regions. One of the main functions that the frontal lobes play in this process is the direction of attention to new stimuli; likewise, in sustained attention with the prefrontal cortex, a ventral attention network has also been postulated, which includes parts of the gyrus. middle and inferior frontal and the temporoparietal cortex (Daffner et al., 2000; Mesulam, 2010; Pardo et al., 1991; Pressman & Rosen, 2015).
Therefore, lesions in the prefrontal cortex may be associated with deficits in tasks that require sustained attention (e.g., pressing buttons in response to specific stimuli) as well as in divided attention tasks (spontaneously tracking multiple stimuli). In daily life, these deficits can be seen in distraction and difficulty with multitasking (for example, not being able to perform a task if the radio or television is on). Failure to attend to novel stimuli may result in perseveration, in which a patient fixates on a task or stimulus even though it is no longer relevant to the immediate situation. A particular phenomenon known as hemineglect (it is common in lesions of the right hemisphere) that is characterized by the neglect of half of the contralateral space (usually left). This phenomenon can be observed with left frontal and/or parietal lesions (Pressman & Rosen, 2015; Zanto & Gazzaley, 2019).
Memory
In relation to , although the typically associated structures are the hippocampus and associated structures, the frontal lobe plays an important role in several aspects. For example, in episodic and working memory the frontal lobe plays a supporting role.
In groundbreaking work using single-cell recording in 1988, Patricia Goldman-Rakic demonstrated that neurons in the dorsolateral frontal cortex function by firing during periods when an animal must store information in memory and then stop recording. same when the animal needs to act on this information. Functional brain imaging studies have shown similar activities in humans. Consequently, patients with frontal lobe damage may develop problems remembering small pieces of information such as a phone number or what they were looking for in a room (Cheryl et al., 1998; Pressman & Rosen, 2015).
A large body of evidence has shown that the frontal lobes are involved in the encoding phase. Functional imaging studies show activation of the prefrontal cortex during encoding and retrieval. Consequently, patients with frontal lobe dysfunction may complain of memory problems that are similar in type and degree to those seen with hippocampal lesions, specifically with retaining information, repeating questions, writing down information to remember, semantically organizing information, and using mnemonic strategies. Likewise, they show deficits in the recovery of previously learned information, being susceptible to interference from competitive information. Finally, the phenomenon of confabulation, where patients not only have difficulty remembering information but also make up information in response to queries, is generally associated with damage to the ventromedial frontal region, prefrontal cortex, and basal forebrain (Gershberg & Shimamura, 1995; Gilboa & Moscovitch, 2002; McKinnon et al., 2007; Shimamura, 1995; Lee et al., 2002; Nyberg et al., 1996; Pressman & Rosen, 2015).
Executive functions
In relation to , which cover a wide range of cognitive activities such as: organizing a response to a complex problem, sequencing tasks, prioritizing external stimuli, abstracting information, among others. They are highly related to the frontal lobe because their functions support and overlap other processes such as the activation of complex motor patterns, the organization of, and the selection of appropriate social behaviors. Basically, these functions depend on the ability to maintain and manipulate information not available in the environment. For this reason, it becomes one of the main functions of the frontal lobe, resulting in various researchers creating different models to explain it (Anderson, 2011; Bertelli et al., 2018; Deright, 2019; Goldman-Rakic et al. , 1996; Hagenhoff et al., 2013; Pressman & Rosen, 2015; Reber & Tranel, 2019).
Although there are many theories that explain the development of executive functions, most researchers agree that the deterioration of executive functions in an individual can be observed through various difficulties that they present in the different contexts in which they participate, for example: the inability to stay focused on a given task, clinically, this would manifest itself in the inability to complete tasks that were initiated on a given trial. Deficits in the planning and execution of complex tasks (planning trips or events such as parties, and even in tasks…