Introduction
The nervous system (and the human brain as its core element) is still one of the most under-researched systems. The development and functioning of the brain have been studied for centuries using diverse approaches. Behavioral, cognitive, and developmental approaches have enabled researchers to explain and describe diverse mechanisms and processes associated with human brain development (Budwig, Turiel, & Zelazo, 2017). The advances in neuroscience made it possible to gain important insights into the matter. Thus, people have learned that the frontal lobe is the brain area that evolves during early childhood and up to young adulthood. This region is responsible for people’s cognitive and emotional abilities (Geschwind & Iacoboni, 2017). This paper dwells upon the development of the frontal lobe in children and plasticity as one of the processes ensuring people’s adaptability to the ever changing environment.
The Development of the Frontal Lobe and Executive Functioning in Children Development of the Frontal Lobe
The frontal lobe can be referred to as the brain region mainly associated with executive functioning, making it central to people’s successful social life. Executive functioning includes such activities as information perception and processing, organization and planning, “self-directed behavior,” behavior control, and decision-making (Lee & Clason, 2016, p. 457). In simple terms, these functions are associated with people’s voluntary acts, such as speech, walking, and problem-solving. Importantly, it was believed that the frontal lobe is the area responsible for these functions. Nevertheless, modern researchers have acknowledged that these activities result from the processes taking place in a complex network that includes the brain region in question. Research on the brain and the development and functioning of the frontal lobe has been implemented for centuries (Miller & Cummings, 2017). However, the advancements in neuroscience have enabled scientists and practitioners to gain new important insights into the matter.
First, it is necessary to consider the peculiarities of the development of the frontal lobe. The frontal lobe is referred to “cortex that lies anterior to the central fissure” (Hodel, 2018, p. 119). This brain area is characterized by the remarkable expansion that occurs during several developmental stages, and it fully developed in people by the age of 26 (Gage & Baars, 2018). However, up to 90% of brain growth terminates at the age of six. During the first two years of life, the grey and white matter of the frontal lobe, as well as the complexity and thickness of the surface area, increase dramatically (Hordel, 2018). It is acknowledged that different areas of the brain develop at a different pace.
The largest part matures in the prenatal period, but some areas, such as the frontal lobe, start rapidly evolving in childhood. Notably, it was believed for a long period of time that the development of the frontal lobe does not start until the age of two (Hordel, 2018). However, neurological imaging enables scientists to prove that this process starts in infancy. As such, the development of the frontal lobe is highly influenced by the environment, making the first years of life critical for the child’s cognitive and social functioning in later years. The different stages of the development of the frontal lobe and executive function as explored by neuroscientists are similar to the phases identified by Piaget, who employed the developmental approach (Bolton & Hattie, 2017). However, the neuroscientific perspective provides more insights into the exact mechanisms of the changes that take place in children’s brains.
Infancy is also a period when frontal-cortical connectivity evolves, making this time critical for the proper development of diverse cognitive and socioemotional functions. During several studies, researchers employed the graph theory to study the organization of the frontal lobe and found significant decreases in the efficiency of the networks in frontal regions during the first two years of life (Hordel, 2018). These changes are attributed to the development of effective networks and the removal of unnecessary or redundant networks.
The research into the development of the frontal lobe (as well as other brain areas) and executive functioning has been associated with the use of several theoretical frameworks. These theories include but are not confined to evolution theory, behavioral and cognitive approaches, and developmental paradigms (Gage & Baars, 2018). The neurobiological approach has also been widely used, and researchers gained various insights into the process of brain development in people. At that, Bardikoff and Sabbagh (2017) claim that the research into the brain and executive functioning development in children (especially young children) is still insufficient.
Development of the Frontal Lobe
As mentioned above, the frontal lobe is responsible for executive functioning development, which is essential for people’s cognition and various voluntary functions. Miyake and Friedman’s theory of executive functions introduced in 2000 is widely used, although some debates regarding certain assumptions are still in place (Bardikoff & Sabbagh, 2017). According to this theoretical framework, executive functioning is divided into three central elements: inhibition, shifting, and updating (Bardikoff & Sabbagh, 2017). Inhibition is a person’s ability to inhibit dominant response patterns in diverse situations. A conventional illustration of this inhibition is the rule all children know and try to follow: they raise their hands instead of shouting if they know an answer to a question (Bardikoff & Sabbagh, 2017). Shifting is another important component that refers to people’s ability to “flexibly transfer between mental sets or rules” (Bardikoff & Sabbagh, 2017, p. 48). Updating is mainly associated with data procession and working memory. This element of executive functioning ensures people’s ability to remember and manipulate (add new information and remove some data) information. Notably, all three components are usually utilized to complete tasks or act in diverse situations.
Although the three elements seem quite similar and even interconnected, they are still distinct parts of executive functioning. The separability of the segments of executive functioning has been supported by the findings of confirmatory factor analysis or latent variable analysis (Bardikoff & Sabbagh, 2017). It is also found that executive functioning and each of its components is manifested with certain variances at different ages. At an early age, children display less developed abilities in either or several elements of executive functioning when completing certain tasks.
The neurodevelopmental approach has gained momentum recently, and researchers have found that the major difference between the brain of a child and adult is associated with connectivity rather than anatomic structure. At that, the insufficient number of studies have involved young children as in the vast majority of cases children, older than six years old, become participants in such research. The interactive specialization framework introduced by Johnson in 2000 is instrumental in understanding these developmental differences (Bardikoff & Sabbagh, 2017). As mentioned above, some neural networks evolve into more complex structures, while some networks become simpler or even disappear. This process is linked to people’s adaptation to the environment and the development of the most suitable behavioral patterns and responses in different circumstances.
Consequences of Injury to the Frontal Lobes During Development
Diverse cognitive and behavioral issues can arise due to brain injury during development. For instance, white matter injury in neonates leads to the development of lesions in different areas, which, in its turn, results in diverse cognitive and behavioral issues (Guo et al., 2017). In the majority of cases, damage to white matter led to impaired motor skills irrespective of the location of the lesion.
It is noteworthy that the outcomes of a brain injury depend on multiple factors, including the severity of the damage, the peculiarities of treatment (if any), and environmental aspects (Gage & Baars, 2018). In terms of the cognitive-behavioral approach, some of the most serious consequences for executive functioning are tied to the so-called “cold” and “hot” cognitive functions (Wood & Worthington, 2017, p. 2). The former include issues with prioritizing, organizing and planning, insufficient attentional flexibility, inadequate concept formation, impaired working memory, and difficulty with or inability to adapt one’s behavior to the changing environment. Hot cognitive functions are social judgment, theory of mind, empathy, and emotional regulation.
Impulse control disorders can be seen as an illustration of the damage to the frontal lobe. These issues are mainly linked to the injury of the orbitofrontal and ventromedial prefrontal cortex and such components of executive functioning as inhibition (Wood & Worthington, 2017). Damage to the prefrontal cortex and anterior cingulate cortex may lead to impairments in inhibition control. The development of such disorders as impulsive aggression is also linked to weak inhibition function and can often be a result of the injury of the medial prefrontal and orbitofrontal cortex. These consequences of the injury of the frontal lobe lead to people’s inability to behave in a socially acceptable way. Injury to the medial orbitofrontal cortex may lead to the development of compulsive behavior and impaired decision-making (Wood & Worthington, 2017). As for hot cognitive functions, they can be damaged as a result of injury to the orbitofrontal and ventromedial prefrontal cortex.
Brain Plasticity and Associated Theories
It has been acknowledged that children’s brains can recover completely or to a considerable extent. Since the frontal lobe is developing at a slower pace compared to other regions, the damage to one area can soon be compensated (Howarth et al., 2016). New neural networks are formed instead of damaged ones, so the injury a child has had often has no long-term effects on cognitive and behavioral aspects. This ability to recover from injuries or impairments is referred to as plasticity (Aharon-Peretz, 2017). Such terms as cognitive plasticity, cognitive modifiability, and neural plasticity are utilized interchangeably, but quite a considerable difference between cognitive and neural plasticity has been identified (Tzuriel, 2021). Neural plasticity is defined as “the brain’s solution to the challenge of integrating new information into its repertoire,” while cognitive plasticity refers to “the modifability of cognition by social interactions and training experiences” (Tzuriel, 2021, p. 4). Further categorization of this complex notion exists as researchers are interested in the exploration of a wide range of aspects of change in the brain.
For instance, neural plasticity includes synaptic pruning and synaptogenesis that refer to the elimination of synapses and their development, respectively, and are two constituent parts of the so-called synaptic plasticity. The synapse is the space between adjacent cells that serves as the channel for communication between cells (Bolton & Hattie, 2017). The following types of synaptic plasticity have been identified: experience-independent, experience-dependent, and experience expectant plasticity. The first type occurs in the pre-natal stage of human development, while the other two types take place during the life span and are influenced by external factors. Experience-expectant plasticity is characterized by the excessive production of neurons, and synaptogenesis is modified due “based on a demarcated region of connectivity” (Bolton & Hattie, 2017, p. 6). Experience-dependent plasticity is associated with the changes in synaptic connections under the influence of stress, learning, experience, or drugs.
Brain plasticity is maximal in early childhood, and with age, this ability declines. Lindenberger and Lövdén (2019) note that this decrease in the brain’s ability to restore is explained by the fact that people have various experiences during their life and many of these external factors remain unchanged. Therefore, the need for high plasticity declines as the body’s resources are allocated to other functions (Lindenberger & Lövdén, 2019). The model of plasticity and stability best illustrates this peculiarity. Systems cannot work at their highest capacity for prolonged periods of time, and the periods of stability serve as the time for resource accumulation.
One of the widely used theoretical frameworks explaining brain plasticity is Hebb’s synaptic theory. In 1949, Donald Hebbs implemented research on some components of neural networks and developed his theoretical paradigm (Langille & Brown, 2018). Hebbs focused on memory and learning and emphasized that certain changes in neural networks led to metabolic changes and, as a result, affected people’s cognition. This neurophysiological approach is now used in various studies that illustrate the changes that occur due to different factors. For example, Maguire and colleges, in their study implemented in London in 2003, provided evidence that people’s cognitive functions affect the volume of white and grey matter (Langille & Brown, 2018). However, this theory has been criticized to some extent or rather updated based on modern neuroscientific data.
Although the assumption that neural networks can evolve and change due to the impact of external factors is not questioned, some aspects of the theory are now reconsidered. For instance, Trettenbrein (2016) notes that the view of the synapse as the core of memory and learning is debatable. The researcher notes that synapse cannot be seen as the source of working memory but also as a gateway and mechanism to reactivate existing memory sets. It is also noted that environmental factors and genetic peculiarities have a significant impact on brain plasticity.
Plasticity has been associated with positive changes and benefits for human development. However, it has been found that this peculiarity is also characterized by an increased vulnerability to brain injury in such cases as hypoxia, inflammation, or ischemia (DeMaster et al., 2019). Prematurity is often referred to as one of the plasticity factors (DeMaster et al., 2019). It has been found that positive environmental experiences can mitigate the negative effects of prematurity and enhance brain plasticity, while negative environmental effects can pose a considerable threat to the brain’s cognitive functions.
In terms of the developmental approach, it has been found that brain plasticity is characterized by different intensities across the lifespan. As mentioned above, plasticity in childhood is high, while this ability in adults and older adults is rather low (Lindenberger & Lövdén, 2019). Importantly, researchers identified critical periods when brakes on plasticity occur. During this time, the changes that have taken place during the period of adaptation are preserved. These stages coincide with the developmental periods that have been illustrated within the scope of developmental theories. Lindenberger and Lövdén (2019) state that certain manipulations and external effects can “open windows of plasticity” (p. 8.9). In simple terms, the ability to adapt to the changing environment can be enhanced in people of all ages, even older adults. Clearly, further research is necessary to explain the exact mechanisms affecting these processes.
Various types of studies that have involved diverse populations have been instrumental in describing the role the frontal lobe and such functions as plasticity play in child development. For instance, Ortiz-Terán et al. (2017) examined neuroplasticity with the focus on multisensory cortices in blind children. It has been acknowledged that blind children’s sensory abilities are reshaped and blindness is often compensated partially by enhanced hearing or other abilities. It has been found that genes play a central role in neuroplasticity, and the frontal lobe changes are facilitated by specific genes (Ortiz-Terán et al., 2017; Colliva et al., 2019). However, the research on the correlation between genetic peculiarities and neuroplasticity is still insufficient, so more data is needed to understand the hereditary mechanisms associated with plasticity.
As far as the use of diverse theoretical frameworks and approaches, developmental models are often used in combination with other paradigms. Cantor et al. (2018) note that developmental theories are instrumental in guiding researchers through the different aspects of people’s cognition and behavior. As mentioned above, brain plasticity is one of the systems that help people adapt to the environment, which has certain peculiarities in different phases of human development.
Conclusion
On balance, it is necessary to note that the frontal lobe is the central brain area responsible for people’s cognition and emotional development. This brain region is not fully developed until early adolescents, with the most rapid growth taking place during early childhood. Developmental, cognitive, behavioral, system-based, and other paradigms have been utilized, but developmental theories remain some of the most widely used frameworks. Thus, neuroscientific evidence supports the major findings of developmental theorists such as Piaget, helping researchers to explain more aspects of the issue.
Brain plasticity is one of the phenomena enabling people to remain adaptive to different external circumstances. The effects of damage to the frontal lobe (as well as any other brain area) may be mediated by plasticity that can be associated with complete or partial recovery from trauma. This ability is maximal in children, but it deteriorates with age. It is stressed that the environment has a substantial influence on plasticity, which is especially evident in young children. Clearly, further research into the exact mechanisms and functions of the frontal lobe development and plasticity is needed. The understanding of these aspects will enable researchers to develop effective strategies to mitigate the negative effects of brain injuries and malfunctions, helping people improve their quality of life.
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