Between 7 and 9 years old, the brain reaches its adult size. However, there is still plenty of brain development happening in the critical years of middle childhood.

The Prefrontal Cortex

The prefrontal cortex is a region of the brain located at the front of the frontal lobe, right behind the forehead. It’s involved in a wide range of complex cognitive processes and plays a crucial role in higher-level functions, which are those cognitive abilities that enable us to plan, reason, problem-solve, and exert self-control, such as:

• Executive function: The prefrontal cortex is often described as the brain’s “executive center” because it oversees and coordinates various cognitive processes. This includes tasks such as decision-making, goal-setting, prioritizing, and multitasking.
• Working memory: Working memory refers to the ability to temporarily hold and manipulate information in the mind for cognitive tasks, such as problem-solving or decision-making. The prefrontal cortex is heavily involved in working memory processes.
• Attention: The prefrontal cortex helps regulate attention, allowing us to focus on relevant information while filtering out distractions. It plays a role in both selective attention (focusing on specific stimuli while ignoring others) and sustained attention (maintaining focus over time).
• Inhibition and impulse control: The prefrontal cortex helps us regulate our emotions and impulses, allowing us to make decisions that are in line with our long-term goals and values.
• Social behavior and decision-making: The prefrontal cortex plays a role in social cognition, including understanding the thoughts, intentions, and emotions of others. It also contributes to social decision-making processes, such as considering the consequences of our actions on others and navigating social interactions.
• Personality and self-awareness: The prefrontal cortex helps us evaluate ourselves, monitor our own behavior, and adapt our actions based on feedback and self-reflection.

The prefrontal cortex is essential for many higher-order cognitive functions that are central to human behavior, personality, and decision-making. Its role extends beyond basic sensory and motor functions, contributing to our ability to navigate the complexities of everyday life and interact with our environment in a purposeful and adaptive manner.

During middle childhood, significant changes occur in the process of myelination in the brain. This period is characterized by continued refinement and maturation of neural circuits, as well as improvements in cognitive, motor, and social-emotional skills. Myelination is a crucial process in the development and functioning of the nervous system. It involves the formation of a fatty substance called myelin, which acts as an insulating sheath that wraps around the axons of neurons, allowing for faster and more efficient transmission of electrical signals along the nerve fibers. Myelination is a dynamic process that begins during prenatal development and continues into early adulthood. It is particularly rapid during infancy and childhood, corresponding to critical periods of brain development and learning. The process is influenced by genetic factors, as well as environmental factors, such as sensory stimulation and experience.

Proper myelination is essential for normal neurological functioning. Disruptions in the myelination process can lead to neurological disorders and impairments in sensory, motor, and cognitive function. Disorders such as multiple sclerosis, for example, involve damage to the myelin sheath, resulting in impaired nerve conduction and neurological symptoms.

Myelination improvement is one factor responsible for these growths. From age 6–12, the nerve cells in the association areas of the brain where sensory, motor, and intellectual functioning connect become almost completely myelinated (Johnson, 2005). This contributes to increases in information processing speed and the child’s reaction time. The hippocampus, which is responsible for transferring information from short-term to long-term memory, also shows increases in myelination resulting in improvements in memory functioning (Rolls, 2000).

Cortisol

Imagine you’re hiking in the wilderness when suddenly you encounter a bear. In this life-threatening situation, your body needs to respond rapidly to ensure survival. This is where cortisol, often referred to as the “stress hormone,” comes into play. As soon as your brain registers the danger, it signals the release of cortisol from your adrenal glands. Cortisol triggers a cascade of physiological responses designed to help you cope with the imminent threat. Your heart rate increases, delivering oxygen-rich blood to your muscles, and your senses sharpen, allowing you to assess the situation more accurately. Cortisol also prompts the release of glucose into the bloodstream, providing a quick source of energy for your muscles. These rapid changes enable you to react swiftly, potentially allowing you to outrun the bear or take evasive action to protect yourself. Once the danger has passed, cortisol levels gradually return to normal, and your body shifts back into a state of rest and recovery. This example illustrates how cortisol serves a crucial role in emergencies, facilitating the body’s adaptive response to acute stressors.

Cortisol plays a crucial role in regulating various physiological processes in the body, including metabolism, immune response, and the sleep-wake cycle. Cortisol levels typically follow a diurnal rhythm, meaning they fluctuate throughout the day. One reason cortisol levels are highest when you wake up is due to the body’s natural circadian rhythm. The circadian rhythm is an internal clock that regulates the sleep-wake cycle, among other biological processes. Cortisol levels begin to rise in the early morning hours, typically peaking within the first hour or so after waking up. This surge in cortisol helps promote alertness and prepares the body for the day ahead.

Another factor contributing to the elevated cortisol levels upon waking is known as the cortisol awakening response (CAR). This is a rapid increase in cortisol levels that occurs within the first 30 to 45 minutes after waking up. The CAR is thought to be influenced by anticipation of the day’s challenges and the body’s preparation for activity and stress. In addition to its role in promoting wakefulness and readiness for the day, cortisol also helps regulate blood sugar levels, metabolism, and immune function. By increasing cortisol levels in the morning, the body ensures that it has the energy and resources necessary to meet the demands of the day ahead.

Throughout the day, cortisol levels gradually taper off. This decline is a natural part of the body’s circadian rhythm and typically continues until cortisol levels reach their lowest point in the late evening and early night hours. The gradual decline helps facilitate the transition from wakefulness to sleep by promoting relaxation and reducing arousal. Lower cortisol levels in the evening also signal to the body that it is time to wind down and prepare for restorative sleep.

The Impact of Emotional Trauma on Brain Development

Trauma can have significant effects on executive function, which refers to a set of cognitive processes that enable individuals to plan, organize, strategize, focus attention, regulate emotions, and control impulses. Here’s how trauma can impact executive function:

• Impaired attention and concentration: Trauma can lead to difficulties in maintaining attention and focusing on tasks. Individuals who have experienced trauma may have heightened sensitivity to potential threats in their environment, leading to distractibility and difficulty sustaining attention on non-threatening stimuli.
• Memory problems: Trauma can affect both short-term and long-term memory processes. Individuals may have difficulty encoding, storing, and retrieving information, particularly if the trauma is associated with intense emotional arousal. This can impact various aspects of executive function, such as planning and decision-making, which rely on the ability to access relevant information from memory.
• Poor impulse control: Trauma can impair the ability to regulate impulses and inhibit inappropriate behaviors. Individuals may react impulsively to perceived threats or stressors, without considering the consequences of their actions. This can lead to difficulties in decision-making and problem-solving, as well as challenges in maintaining social relationships.
• Emotional dysregulation: Trauma can disrupt the regulation of emotions, leading to heightened emotional reactivity and difficulty modulating affective responses. This can interfere with the ability to think clearly and make reasoned judgments, as well as impairing interpersonal communication and conflict resolution skills.
• Executive dysfunction: Trauma can result in general executive dysfunction, affecting the ability to plan, organize, and execute complex tasks. Individuals may struggle with setting goals, prioritizing tasks, and breaking tasks down into manageable steps. This can impact academic and occupational performance, as well as daily functioning in various domains.

When people experience chronic circumstances, such as poverty or trauma, their cortisol levels do not drop off as they should after the immediate threat has passed. Instead, the body remains in a state of heightened arousal, with cortisol levels staying elevated over extended periods. This chronic activation of the stress response can have profound consequences for physical and mental health. Over time, it can contribute to a range of health problems, including hypertension, cardiovascular disease, obesity, and weakened immune function. Furthermore, prolonged exposure to elevated cortisol levels can disrupt brain development, impair cognitive function, and increase the risk of mental health disorders, such as anxiety and depression. Thus, while cortisol is vital for survival in acute emergencies, its dysregulation in chronic stress situations underscores the importance of addressing underlying social and environmental factors to promote health and well-being.

Licenses and Attributions for Brain Development

“Brain Development” by Terese Jones is licensed under CC BY 4.0.