1.1. Introduction to brain structure and cognitive processes
The brain is the most complex organ in the human body and one of the most advanced biological systems. It controls all body functions, such as movement, sensing the environment, emotions, language, memory, and thinking. The brain is responsible for our thoughts, feelings, memory, and ability to learn. It is made up of more than 100 billion neurons — nerve cells that send and process information. These cells help us make decisions, learn new things, and respond to what is happening around us. To better understand how the brain works, it is helpful to learn about its structure and basic cognitive functions (Maldonado & Alsayouri, 2023).
The basic structure of the brain is the neuron, which is a nerve cell that sends information. It works like a wire that passes signals. It does this using both electrical and chemical signals.
A neuron has three main parts:
- Cell body (soma) – This is the centre of the neuron, where the cell’s nucleus is located. It processes information and keeps the cell alive.
- Dendrites – These are thin “branches” that receive signals from other neurons and send them to the cell body. You can think of them like antennas that catch signals.
- Axon – This is a long “tube” that carries the signal to other neurons or muscles. The axon is covered with a myelin sheath, which works like insulation on an electric wire, helping the signals travel faster.
Neurons pass information in two ways:
| Electric impulse (inside the neuron), meaning a signal transmitted within the nerve cell. | Chemical transmitters (between neurons) |
| Inside the neuron, signals are transmitted in the form of an electric impulse, which travels from the dendrites, through the cell body, all the way to the end of the axon. | ·Neurons are not directly connected – there is a synapse (a microscopic gap) between them. ·When an electric impulse reaches the end of the axon, it triggers the release of neurotransmitters – special chemical substances. ·These chemical substances (neurotransmitters) cross the tiny gap between cells and transmit the information further |
Example of how a neuron works:
If you touch something hot, the neurons in your skin quickly send a signal to your brain. The brain processes the information and sends a command to the muscles in your hand to pull it back. All of this happens in a fraction of a second! Thanks to this network of connected neurons, we can think, feel, move, and respond to our surroundings.
1.2. Basics of brain regions
The brain can be divided into three main parts:
Gray matter and white matter – how do they work?
The brain and spinal cord are made up of grey matter and white matter, but it is the grey matter that plays a key role in everyday human functioning (Mercadante & Tadi, 2023).
What is grey matter?
- It is the outer layer of the brain, responsible for thinking, decision-making, and processing information.
- It is also found in the spinal cord and helps send signals to the muscles.
- It gets its grey colour from the large number of nerve cell bodies (neurons).
What is white matter?
- White matter lies beneath the grey matter and connects different parts of the brain, allowing information to be transmitted between them.
How does the brain develop?
During adolescence, the brain goes through major changes that affect how we think, make decisions, and control emotions. This process is important for shaping a mature personality and developing intellectual abilities (Miguel-Hidalgo, 2013).
During adolescence, the structure of the brain changes:
✔️ Reduction of grey matter – grey matter contains the bodies of nerve cells and is responsible for processing information. During adolescence, the brain “prunes” unused neural connections, which helps it work more efficiently.
✔️ Increase in white matter – white matter is made of nerve fibres covered by a myelin sheath, which speeds up the transmission of information. More white matter means better communication between different areas of the brain (Miguel-Hidalgo, 2013).
During adolescence, cognitive abilities and emotional control continue to develop:
✔️ The part of the brain responsible for thinking and planning (the prefrontal cortex) develops later than the part responsible for emotions (the limbic system). This is why teenagers may react more impulsively.
✔️ Connections between the prefrontal cortex and the limbic system develop over time. As these connections strengthen, emotional control and the ability to make rational decisions improve — but this process continues until about age 25.
Because of this, the teenage brain is more vulnerable to addiction from psychoactive substances (Miguel-Hidalgo, 2013).
Adolescence is also a time when hormones affect the brain:
✔️ Sex hormones (testosterone, estrogen) influence brain development, which can lead to differences in how the brain works in boys and girls.
✔️ Increased sensitivity to emotions and stress – The teenage nervous system is more reactive to stress and strong emotions. This affects behaviour and the ability to cope with difficult situations (Miguel-Hidalgo, 2013).
The Importance of adolescence for learning and development:
✔️ The teenage brain is highly plastic, which means it has a great ability to learn and adapt. This is the best time to develop new skills, but also a time when negative habits can form easily.
✔️ Adolescence is a key period for shaping habits, lifestyle, and personality. That’s why it is important to support the cognitive, emotional, and social development of young people (Miguel-Hidalgo, 2013).
What brain changes are typical in mental disorders?
Mental disorders are often linked to unusual changes in the structure and function of the brain. Some brain areas may develop differently than in healthy individuals, which can affect emotions, impulse control, and decision-making.
1. Key brain areas involved in mental disorders
✔️ Prefrontal cortex – responsible for logical thinking, planning, and impulse control. When this area is underactive, it can lead to problems with making rational decisions and increased impulsiveness.
✔️ Amygdala – plays an important role in processing emotions, especially fear and stress. Overactivity in this area can lead to anxiety, while reduced activity may cause difficulty in feeling emotions.
✔️ Ventral striatum – part of the brain’s reward system and important for experiencing pleasure. Problems in this area can increase the risk of addiction and cause difficulties with motivation (Miguel-Hidalgo, 2013).
2. How do brain changes affect behaviour?
✔️ Overactivity in certain brain areas can lead to stronger emotional reactions, higher levels of anxiety, impulsive behaviour, or problems with self-control.
✔️ Reduced activity in some brain structures may cause difficulty in managing emotions, apathy, trouble making decisions, and low stress tolerance.
✔️ Abnormal development of connections between brain areas can make it harder for a person to adapt to different situations, increasing the risk of depression, anxiety disorders, or risky behaviours (Miguel-Hidalgo, 2013).
3. The importance of brain research in treating mental disorders
Understanding these brain changes helps scientists and doctors develop more effective treatments, such as psychological therapies, medications, and techniques that support neuroplasticity (the brain’s ability to adapt and change). As a result, people struggling with mental health problems can receive better support and more effective care (Miguel-Hidalgo, 2013).
Overactive or underactive emotional brain areas. In teenagers, the activity of the amygdala (which processes emotions) can be stronger than in children or adults.
In individuals with mood disorders (such as depression), the activity of the ventral striatum (the brain’s reward centre) is often too low. This may help explain why they feel a lack of motivation and joy (Miguel-Hidalgo, 2013).
Example:
Research shows that higher activity in the ventral striatum in healthy teenagers is linked to positive emotions and a lower risk of depression.
Immature prefrontal cortex and lack of emotional control
The part of the brain responsible for thinking and planning develops later than the part that handles emotions. This is why teenagers may react impulsively. In people with mental disorders, this imbalance can be even stronger, leading to impulsive behaviour, difficulty regulating emotions, and risky decision-making (Miguel-Hidalgo, 2013).
Example:
People with addictions often have reduced activity in the prefrontal cortex, which makes it harder for them to control their behavior and avoid risky situations. This is why addiction should not be seen as a lack of willpower, but as a brain disorder.
Structural and Functional Changes in Mental Disorders
The table below presents the main structural and functional changes observed in selected mental disorders, such as schizophrenia, anxiety disorders, depression, and addiction. To help with understanding, the table also includes comments with explanations.
| Disorder | What changes in brain structure? (Structural changes) | How does it affect behaviour and emotions? (Functional changes) | Comment with explanation |
| Schizophrenia | Some brain areas (e.g., frontal and temporal lobes) are smaller. Connections between nerve cells are weaker. | Difficulty with thinking, delusions and hallucinations (e.g., hearing voices), problems with emotions. | The brain does not work like an “efficient network” – it becomes harder to understand reality, and thoughts or voices may appear that are not real. |
| Anxiety Disorders | The amygdala (the brain area involved in fear) is overactive. The prefrontal cortex (responsible for control) is underactive. | The person feels fear easily, has trouble calming anxiety, and experiences tension | The brain overreacts to stress, as if there is constant danger. The person may feel ongoing worry or unease. |
| Depression | The hippocampus (important for memory and emotions) is smaller. The amygdala is more active. Structures in the front part of the brain show changes. | Sadness, lack of energy, difficulty concentrating, emotional problems. | The brain struggles to manage emotions – the person feels sad, tired, and unable to focus. |
| Addictions | Impaired brain connections (especially in the white matter), damage to the hippocampus and prefrontal cortex. | Difficulty controlling behavior, impulsiveness, risky decision-making. | The brain’s “braking system” is weakened – the person has trouble saying “stop” and acts impulsively, even when they know something is harmful. |
Based on information from: Miguel-Hidalgo JJ. Brain structural and functional changes in adolescents with psychiatric disorders. International Journal of Adolescent Medicine and Health. 2013;25(3):245–256.
To assess your knowledge on this topic, do exercise 5 in the exercise book
1.3. Cognitive function E.G. Memory, Learning, Concetration
What is cognitive health and how can we take care of it?
Cognitive health allows us to live independently, maintain social relationships, and handle everyday challenges. According to Hendrie et al. (2006), cognitive health helps people stay independent, cope better with illness, and adapt to life changes.
Main elements of cognitive health:
✔️ Mental abilities – such as decision-making and problem-solving
✔️ Acquired skills – knowledge and experience gained over time
✔️ Applying learned skills in practice – using knowledge to perform everyday tasks (Puri et al., 2023).
How does the brain support cognitive health?
The brain is responsible for:
• Thinking and memory: it helps us learn and remember information
• Motor functions: it controls body movements and balance
• Emotional functions: it helps us understand and manage emotions
• Sensory functions: it allows us to feel and respond to stimuli from the environment
A healthy brain helps us adapt to different situations, manage emotions, and act independently (Puri et al., 2023).
What affects cognitive health?
Some changes in the brain are natural, but there are factors that can improve or worsen cognitive health:
🔹Uncontrollable factors – e.g. age, genetics, and illness
🔹Controllable factors:
✔️ A healthy diet and physical activity – support brain function
✔️ Social connections – help maintain mental sharpness
✔️ Intellectual activity – such as learning new things or solving puzzles
✔️ Avoiding smoking and excessive alcohol – lowers the risk of cognitive problems (Puri et al., 2023)
People who live an active lifestyle and take care of their minds can keep good memory and thinking skills for longer, even as their brains go through gradual changes. Although brain aging is a natural process, a healthy lifestyle, mental activity, and social engagement can improve and extend cognitive function and lower the risk of neurodegenerative diseases (Puri et al., 2023).
Cognitive functions
Cognitive functions are the processes that allow us to learn, remember information, focus, and solve problems. Here are the most important ones:
1. Memory: Memory allows us to store and recall information. It is divided into ….
Example:
After making a healthy breakfast (like oatmeal with fruit) many times, you no longer need to check the recipe — you just remember how to do it. Thanks to this type of memory, you also remember general rules of healthy eating.
Example:
After making a healthy breakfast (like oatmeal with fruit) many times, you no longer need to check the recipe — you just remember how to do it. Thanks to this type of memory, you also remember general rules of healthy eating.
Example:
You make coffee or tea every morning without thinking about each step. You know exactly how much water to boil, where the cup is, and how to prepare it — your hands just do it. This is procedural memory in action.
2. Learning: Learning is the process of gaining new knowledge and skills. Our brain changes as a result of experiences. This is called brain plasticity. Regular learning strengthens the connections between neurons, which makes it easier to remember things.
Example: If we practice foreign language vocabulary every day, our brain learns and recognizes the words more quickly.
Example:
You make coffee or tea every morning without thinking about each step. You know exactly how much water to boil, where the cup is, and how to prepare it — your hands just do it. This is procedural memory in action.
3. Concentration
Concentration is the ability to focus attention on a specific task. It is essential for effective learning and work. Many factors affect attention, such as stress, noise, or the amount of sleep.
How to improve concentration?
✔️ Limit distractions (e.g. phone, social media)
✔️ Take breaks – the brain needs rest to absorb information
✔️ Practice mindfulness – it helps improve focus
✔️ Pay attention to getting enough sleep – 8 hours
To assess your knowledge on this topic, do exercise 5 in the exercise book
| References |
| Maldonado, K. A., & Alsayouri, K. (2023). Physiology, brain. In StatPearls. StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK551718/ Mercadante, A. A., & Tadi, P. (2023). Neuroanatomy, gray matter. In StatPearls. StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK538304/ LeDoux, J. E. (2012). Evolution of human emotion: A view through fear. Progress in Brain Research, 195, 431–442. https://doi.org/10.1016/B978-0-444-53860-4.00021-0 Miguel-Hidalgo, J. J. (2013). Brain structural and functional changes in adolescents with psychiatric disorders. International Journal of Adolescent Medicine and Health, 25(3), 245–256. https://doi.org/10.1515/ijamh-2013-0058 Hendrie, H. C., Albert, M. S., Butters, M. A., Gao, S., Knopman, D. S., Launer, L. J., et al. (2006). The NIH cognitive and emotional health project: Report of the critical evaluation study committee. Alzheimer’s & Dementia, 2(1), 12–32. https://doi.org/10.1016/j.jalz.2005.11.004 Puri, S., Shaheen, M., & Grover, B. (2023). Nutrition and cognitive health: A life course approach. Frontiers in Public Health, 11, 1023907. https://doi.org/10.3389/fpubh.2023.1023907 |