**3. Cognitive development of PFC**

PFC mediate several cognitive abilities and they develop fundamentally during early childhood in terms of age-related improvements, and functional neural systems for each function become more separable through development [58]. In this section, we reviewed cognitive abilities and their development which are mediated by the PFC.

#### **3.1. Attentional development**

The attention properties fall into five basic categories: alertness, set, spatial attention, sustained attention, and interference control [77].

Although by 3 years of age, children can make the occasional perseverative error; they inhibit instinctive behaviors well [78]. Improvements in speed and accuracy on impulse control tasks can be observed up to 6 years of age [78, 79]. However, an increase in impulsivity occurs for a short period around 11 years of age, children aged 9 years and older are able to monitor and regulate their actions well [80].

The components of attention seem to develop gradually toward full maturity at about 12 years, with maximum development between the ages of 6 and 9 [81, 82].

#### **3.2. Memory**

Neuropsychological and functional neuroimaging evidence implicated the importance of the PFC, supports particularly the development of episodic memory [83]. Functional neuroimaging studies consistently show increasing in PFC activation that supports the formation [84] and retrieval of episodic memories [85].

Although the frontal lobe damage usually does not cause loss of perceptual memory, it does in some cases especially if the lesion involves the left prefrontal cortex that causes the inability to encode and retrieve serial tasks [86], stories [87], and verbal material [88]. Particularly, if the lesion includes the orbitolimbic region, it can cause the presence of spontaneous confabulation and false recall or recognition [87].

In the recent study, the PFC contribution to subsequent memory (SM) in children, adolescents, and young adults was investigated. It is showed that regions in the lateral PFC showed positive SM effects, whereas regions in the superior and medial PFC showed negative SM effects. Both positive and negative SM effects increased with age. The magnitude of negative SM effects in the superior PFC partially mediated the age-related increase in memory. Functional connectivity between lateral PFC and regions in the medial temporal lobe (MTL) increased with age during successful memory formation [83]. In the study of Qin et al., they examined age-related changes in brain activity associated with memory-based arithmetic and found increased working of memory-based strategies for solving arithmetic problems across a period of 14 months in children ages 7–9. Paralleling these behavioral findings, increased functional connectivity between the lateral prefrontal cortex (IFG/MFG) and the hippocampus was observed [89].

#### **3.3. Working memory**

The myelination of the frontal lobe can continue into the 3rd decade of life [71]. The anterome-

When reviewed the fMRI studies, many of these studies have reported that the responsible regions in the PFC show age-related increases in activity through development in schoolage children and adolescents [73–75]. In the Kwon et al. study, they observed an age-related linear increase in activity in the lateral PFC during the n-back working memory task from 7 to 22 years of age [73]. In contrast, in the brain regions less critical to the tasks tested has also been reported age-related decrease in neural activity [75]. These patterns of age-related activity changes are thought to indicate a developmental shift in functional neural organizations

PFC mediate several cognitive abilities and they develop fundamentally during early childhood in terms of age-related improvements, and functional neural systems for each function become more separable through development [58]. In this section, we reviewed cognitive

The attention properties fall into five basic categories: alertness, set, spatial attention, sus-

Although by 3 years of age, children can make the occasional perseverative error; they inhibit instinctive behaviors well [78]. Improvements in speed and accuracy on impulse control tasks can be observed up to 6 years of age [78, 79]. However, an increase in impulsivity occurs for a short period around 11 years of age, children aged 9 years and older are able to monitor and

The components of attention seem to develop gradually toward full maturity at about 12 years,

Neuropsychological and functional neuroimaging evidence implicated the importance of the PFC, supports particularly the development of episodic memory [83]. Functional neuroimaging studies consistently show increasing in PFC activation that supports the formation [84]

Although the frontal lobe damage usually does not cause loss of perceptual memory, it does in some cases especially if the lesion involves the left prefrontal cortex that causes the inability to encode and retrieve serial tasks [86], stories [87], and verbal material [88]. Particularly, if the lesion includes the orbitolimbic region, it can cause the presence of spontaneous confabula-

dial aspect of the frontal lobe is one of the last regions, to myelinate postnatally [72].

more focal, fine-tuned systems [76].

8 Prefrontal Cortex

**3.1. Attentional development**

regulate their actions well [80].

and retrieval of episodic memories [85].

tion and false recall or recognition [87].

**3.2. Memory**

**3. Cognitive development of PFC**

tained attention, and interference control [77].

abilities and their development which are mediated by the PFC.

with maximum development between the ages of 6 and 9 [81, 82].

Working memory is the one of neural functions for temporary storage and manipulation of information [90]. It is necessary for other cognitive functions, such as language comprehension, reasoning, and learning [91]. Behavioral measures showed that working memory systems improve fundamentally during early childhood [92].

Kaldy and Sigala [93] observe that 9-month-old infants can integrate the visual features of an object with its location as part of the content of working memory. On the conclusion of findings, they speculate that the early development of the *what-where* integration in working memory [93].

Luciana and Nelson's study showed that in normal children, aged 4–8 years, the prefrontal working memory system emerges at around the age of 4 and improves between 5 and 7 years of age [94], and capacity of visual short-term memory increases also substantially between 5 and 11 years of age [95]. Additionally, age-related improvement of working memory for phonological information has also been observed during early childhood from 4 years of age [96]. Consistent with these findings, fMRI studies in children indicated that the lateral PFC functions in healthy children as young as 4 years, and the neural systems of this area responsible for working memory gradually mature at 4–7 years of age [97]. In conclusion all of them, the child reaches the mature level of performance by age 10–12 years [77].

In the development of working memory, not only PFC plays role, but also stronger frontoparietal connectivity underlies the development of working memory. Edin et al. indicated that the weak connectivity among subregions of the PFC might also be important for the functional development of the PFC [98]. It can be summarized that functional maturation of the PFC is tightly linked to changes in several other brain regions [99].

#### **3.4. Planning**

The effective planning is crucial to self-organization and it involves setting a goal, formulating a checklist of tasks necessary to achieve it, and executing each one until the goal is achieved. Studies suggest that children and adolescents are identified as deficient in planning skills, which is not surprising given that executive functions improve especially through adolescence [100, 101]. The failure to formulate plans, especially new plans, is generally accepted as being a common feature of prefrontal syndromes. Especially, the symptom appears unique to dysfunction of the prefrontal cortex [77].

**3.7. Language**

by frontal damage [115].

adolescence [107, 117].

**3.8. Social behavior**

adolescence.

reach full maturity until that time [77].

resolving conflict in social cues [123].

**3.9. Theory of mind and mentalizing**

talizing, which to have been associated with rostral PFC.

The spoken language is based on the exercise of temporal integration and the cognitive functions. For this reason, language has been found to be adversely affected in a variety of ways

Development Period of Prefrontal Cortex http://dx.doi.org/10.5772/intechopen.78697 11

In early childhood, increase in speed and verbal fluency of language is observed, particularly between 3 and 5 years of age [102, 116]. Processing speed and fluency continues to improve during middle childhood [80, 102] with significant gains in processing speed observed between 9–10 and 11–12 years [117]. Improvements in efficiency and fluency occur during

However, higher cognitive functions such as language and intelligence continue to develop into the 3rd decade of life, supported by the lateral prefrontal cortex, which does not seem to

Social cognition defines to identify and interpret social signals, and the use of those signals to guide the flexible performance of appropriate social behaviors given in changing situations [118]. The PFC is connected with several cortical and subcortical regions of the brain, including nucleus accumbens (NAc), amygdala, ventral tegmental area (VTA), hypothalamus, and regions of the cortex involved in processing sensory and motor inputs. PFC is also connected with which regions known as social brain, so PFC has been played rol in also social behavior [119, 120]. Many studies have demonstrated the importance of the vmPFC for social motivation and reward. The vmPFC is also engaged with social acceptance feelings and is activated learning with cues of related with social reward [121, 122]. The lateral PFC is also a part of a network that process in the social domain, such as imitation, abstract social reasoning, and

The mPFC is responsive to social stimuli in developing infants [124]. In particular, the mPFC activates at the infant with viewing a mothers smile, or hearing infant directed speech [125]. Studies with children and adolescents focus on amygdala and findings of these studies showed an association between cerebral maturation and increased regulation of emotional behavior; the latter mediated by prefrontal systems [126, 127]. In another study, findings suggest that the adult brain better modulated OFC activity based on attention demands, while the adolescent brain better modulated activity based on the demands of emotion. So, if there were no attentional demands, emotional content of the stimuli-induced higher activity in ACC, OFC and amygdala in the adolescents compared with the adults [128]. These fMRI results show that both the brain's emotion processing systems develop during

Theory of mind (ToM) is the ability of an individual to mean the feelings, motives, opinions, and emotions of another on the basis of his or her expressions. It is a necessary ability for meaningful social interaction [77]. Some studies have investigated the development of men-

Simple planning skills are observed by 4-year-olds [102]. Similarly by 4 years of age children are skillful of create new concepts [103]. When the aims are made clear, at the age of 6 years children can make detailed plans [104]. Planning and organizational skills develop rapidly between 7 and 10 years of age [105] and gradually after into adolescence [102]. Young children use simple strategies, which are usually ineffective but between 7 and 11 years of age strategic behavior and reasoning abilities become more organized [106]. The planning seems to develop at about 12 years with the plateau and around 12–13 years of age, regression from conceptual strategies to piecemeal strategies may occur and it suggesting a developmental period in which cautious and conservative strategies are preferred. Improving of strategies and decision making continues during adolescence [107]. Studies have reported improved the planning skills into the 20s [108, 109]. In addition, the inter-correlations observed between planning skills and other neuropsychological tasks and IQ, during adolescent development of planning abilities [110].

#### **3.5. Temporal integration**

Temporal integration is the ability to organize temporally separate items of perception and action into goal-directed thinking, speech, or behavior. This ability derives from the joint and temporally extended operation of attention, memory and planning. In neural terms, it derives from the cooperation of the prefrontal cortex with other cortical and subcortical regions. In a study, age-dependent comparisons were made between 9–10- and 13–14-year-olds and these findings suggested that children used a similar strategy as adults and indicate a stabilizing and optimalizing process by the age of approximately 13–14 years with respect to subjective rhythmization [111].

In conclusion, the temporal integration seem to develop at about 12–13 years as same as development of working memory and planning [77].

#### **3.6. Inhibitory control**

Inhibitory controls the ability to suppress information and actions that are inappropriate situations and it is important for several cognitive abilities and adaptive behaviors [99]. The children aged 2.5 years were able to inhibit the prepotent tendency on the spatially incompatible trials and by 3 years, they were correct 90% of the time [112].

Several studies have demonstrated that performance on the cognitive tasks that requires inhibitory control, improves throughout childhood over the ages of 4 years [6, 99, 109].

The fMRI studies suggest a change in the recruitment of rostral PFC (BA10) in situations of response inhibition during late childhood and adolescence. An increase in BOLD signal in this region [113] initially and then a decrease in BOLD signal [114] seems consistent with the anatomical findings suggesting that gray matter volumes in the frontal cortex [59].

In summary, the ability inhibitory control develops both anatomically and functionally significantly during early childhood.

#### **3.7. Language**

which is not surprising given that executive functions improve especially through adolescence [100, 101]. The failure to formulate plans, especially new plans, is generally accepted as being a common feature of prefrontal syndromes. Especially, the symptom appears unique to

Simple planning skills are observed by 4-year-olds [102]. Similarly by 4 years of age children are skillful of create new concepts [103]. When the aims are made clear, at the age of 6 years children can make detailed plans [104]. Planning and organizational skills develop rapidly between 7 and 10 years of age [105] and gradually after into adolescence [102]. Young children use simple strategies, which are usually ineffective but between 7 and 11 years of age strategic behavior and reasoning abilities become more organized [106]. The planning seems to develop at about 12 years with the plateau and around 12–13 years of age, regression from conceptual strategies to piecemeal strategies may occur and it suggesting a developmental period in which cautious and conservative strategies are preferred. Improving of strategies and decision making continues during adolescence [107]. Studies have reported improved the planning skills into the 20s [108, 109]. In addition, the inter-correlations observed between planning skills and other neuropsychological tasks and IQ, during adolescent development of planning abilities [110].

Temporal integration is the ability to organize temporally separate items of perception and action into goal-directed thinking, speech, or behavior. This ability derives from the joint and temporally extended operation of attention, memory and planning. In neural terms, it derives from the cooperation of the prefrontal cortex with other cortical and subcortical regions. In a study, age-dependent comparisons were made between 9–10- and 13–14-year-olds and these findings suggested that children used a similar strategy as adults and indicate a stabilizing and optimalizing process by the age of approximately 13–14 years with respect to subjective

In conclusion, the temporal integration seem to develop at about 12–13 years as same as

Inhibitory controls the ability to suppress information and actions that are inappropriate situations and it is important for several cognitive abilities and adaptive behaviors [99]. The children aged 2.5 years were able to inhibit the prepotent tendency on the spatially incompat-

Several studies have demonstrated that performance on the cognitive tasks that requires inhibitory control, improves throughout childhood over the ages of 4 years [6, 99, 109].

The fMRI studies suggest a change in the recruitment of rostral PFC (BA10) in situations of response inhibition during late childhood and adolescence. An increase in BOLD signal in this region [113] initially and then a decrease in BOLD signal [114] seems consistent with the

In summary, the ability inhibitory control develops both anatomically and functionally sig-

anatomical findings suggesting that gray matter volumes in the frontal cortex [59].

dysfunction of the prefrontal cortex [77].

10 Prefrontal Cortex

**3.5. Temporal integration**

rhythmization [111].

**3.6. Inhibitory control**

nificantly during early childhood.

development of working memory and planning [77].

ible trials and by 3 years, they were correct 90% of the time [112].

The spoken language is based on the exercise of temporal integration and the cognitive functions. For this reason, language has been found to be adversely affected in a variety of ways by frontal damage [115].

In early childhood, increase in speed and verbal fluency of language is observed, particularly between 3 and 5 years of age [102, 116]. Processing speed and fluency continues to improve during middle childhood [80, 102] with significant gains in processing speed observed between 9–10 and 11–12 years [117]. Improvements in efficiency and fluency occur during adolescence [107, 117].

However, higher cognitive functions such as language and intelligence continue to develop into the 3rd decade of life, supported by the lateral prefrontal cortex, which does not seem to reach full maturity until that time [77].

#### **3.8. Social behavior**

Social cognition defines to identify and interpret social signals, and the use of those signals to guide the flexible performance of appropriate social behaviors given in changing situations [118]. The PFC is connected with several cortical and subcortical regions of the brain, including nucleus accumbens (NAc), amygdala, ventral tegmental area (VTA), hypothalamus, and regions of the cortex involved in processing sensory and motor inputs. PFC is also connected with which regions known as social brain, so PFC has been played rol in also social behavior [119, 120]. Many studies have demonstrated the importance of the vmPFC for social motivation and reward. The vmPFC is also engaged with social acceptance feelings and is activated learning with cues of related with social reward [121, 122]. The lateral PFC is also a part of a network that process in the social domain, such as imitation, abstract social reasoning, and resolving conflict in social cues [123].

The mPFC is responsive to social stimuli in developing infants [124]. In particular, the mPFC activates at the infant with viewing a mothers smile, or hearing infant directed speech [125]. Studies with children and adolescents focus on amygdala and findings of these studies showed an association between cerebral maturation and increased regulation of emotional behavior; the latter mediated by prefrontal systems [126, 127]. In another study, findings suggest that the adult brain better modulated OFC activity based on attention demands, while the adolescent brain better modulated activity based on the demands of emotion. So, if there were no attentional demands, emotional content of the stimuli-induced higher activity in ACC, OFC and amygdala in the adolescents compared with the adults [128]. These fMRI results show that both the brain's emotion processing systems develop during adolescence.

#### **3.9. Theory of mind and mentalizing**

Theory of mind (ToM) is the ability of an individual to mean the feelings, motives, opinions, and emotions of another on the basis of his or her expressions. It is a necessary ability for meaningful social interaction [77]. Some studies have investigated the development of mentalizing, which to have been associated with rostral PFC.

When investigating the development of ToM, children develop an understanding of desires, goals, and intentions at around 18 months firstly, and then the understanding of many mental states such as wanting, knowing, pretending, or believing is available in implicit form to 2-year-olds. Typical tests of mentalizing develop at about 4 years old in children [129]. At the age of 6 years, all typically developing children understand the tasks, involving more complex scenarios [130].

depression, autism, etc. As we know more about the prefrontal cortex, we think that we could better understand these psychiatric disorders and could develop new treatment options.

Development Period of Prefrontal Cortex http://dx.doi.org/10.5772/intechopen.78697 13

Department of Child and Adolescent Psychiatry, Kayseri Training and Research Hospital,

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373-385

**Author details**

Merve Cikili Uytun

Kayseri, Turkey

**References**

Address all correspondence to: mervecikili@yahoo.com

ogy. Progress in Brain Research. 2012;**195**:191-218

A functional MRI study investigated the development of mentalizing by the task and found that children (between 9 and 14 years old) engaged frontal regions includes medial PFC and left inferior frontal gyrus more than adults did in this task [131]. In another study, adolescent (12–18 years) and adults participants (22–37 years) were scanned with functional MRI and the results showed that adolescents activated part of the medial PFC more than adults did, and adults activated part of the right superior temporal sulcus more than adolescents did. These results suggest that the neural strategy for mentalizing changes between adolescence and adulthood. Although the same neural network is active, the relative roles of the different areas change, with activity moving from anterior (medial prefrontal) regions to posterior (temporal) regions with age [132].
