Yes, our brains continue to create new neurons throughout our lives!


Neurogenesis is the process of forming new neurons in the brain. Although it was long thought that this process was limited to the prenatal period and early childhood, research has revealed that neurogenesis persists, to a lesser degree, into adulthood in certain regions of the brain.
Here are the main aspects of neurogenesis:
- Developmental period : Neurogenesis is particularly active during foetal development and early childhood, when large numbers of new neurons are produced to form brain structures. The migration of neurons to the cerebral cortex is an important process that takes place during the developmental period.
- Neurogenesis in adulthood: Although the rate of neurogenesis decreases with age, the formation of new neurons continues in certain areas of the adult brain. The main areas where neurogenesis occurs are :
o The hippocampus, involved in memory and learning.
o The subventricular zone (SVZ), from which neurons migrate to the olfactory bulb.
- Factors influencing neurogenesis: Several factors can influence neurogenesis, including :
o Physical activity: Physical exercise has been shown to stimulate neurogenesis in the hippocampus.
o Enriched environment: A stimulating environment rich in experiences promotes neurogenesis.
o Neurotrophic factors: These are substances that are important for the survival, development and function of neurons.
o Diet and adequate nutrition are fundamental to brain development. Malnutrition can have negative effects on neurogenesis.
-Stress and depression: can inhibit neurogenesis.
- Role of neurogenesis in learning and brain plasticity: Neurogenesis plays a role in brain plasticity, enabling the brain to adapt to new experiences. The new neurons that form in the hippocampus are involved in the formation of new memories and learning. Learning modifies the brain by reorganising cerebral connections.
- Neurogenesis and disease: Neurodevelopmental disorders can be linked to alterations in neurogenesis. Problems with neuronal migration during development can lead to malformations.
It is important to note that neurogenesis is a complex process that is still being studied. Although research has made significant progress in understanding this phenomenon, many questions remain unanswered about the precise mechanisms of neurogenesis, its role in various brain functions and its therapeutic potential.
In a nutshell, neurogenesis is the formation of new neurons that occurs mainly during development, but also persists in certain regions of the adult brain. It is influenced by factors such as physical activity, the environment, neurotrophic factors and stress, and is essential for brain plasticity and learning.
So there's no age limit for continuing to learn!


The brain is constantly recreating reality


 

The brain is constantly reconstructing reality, because our perception is limited and the brain has to fill in the missing information to create a coherent experience. This reconstruction is influenced by various internal and external factors.

Here's how the brain goes about this reconstruction and the implications of this process:
* Limited perception**: Our senses capture only part of reality. For example, we can only see part of the visible light spectrum and our hearing does not perceive all sound frequencies. Similarly, our sense of touch does not feel the different atoms on a surface, but rather interprets information at a macro level. The brain uses the limited signals it receives to construct a representation of the world.
* Completion and coherence**: From this fragmentary and limited sensory information, the brain fills in the gaps to create a coherent perception. It does not just passively record information, but actively interprets and completes it. The brain works like a ‘controlled hallucination’, where some of the information comes from outside and some is generated by the brain from its own knowledge and experience.
* Influence of preconceived ideas**: This reconstruction is strongly influenced by our past experiences, beliefs, emotions, political opinions, culture and preconceived ideas. **The brain uses stored knowledge to anticipate events**. Imaginary mental representations help us to remember an object that is not in our field of perception.
* Memory and reconstruction**: Memory does not function as a faithful record of the past, but rather as a reconstruction in the present. Each time we remember something, we modify and reinterpret it in the light of our current state.  Memories are therefore a reconstruction, not an exact reproduction of the past. **It is even possible to implant false memories through suggestion and imagination**.
* The role of attention**: Attention plays an essential role in perception and memory. What we don't pay attention to is often not remembered and therefore seems to have disappeared, because the brain does not process details that are not targeted by attention.
* Uncertainty and ambiguity**: The more uncertain or ambiguous a subject, the more likely the brain is to reconstruct it according to our preconceptions.  In situations of high uncertainty, the brain will fill in the gaps based on our past experiences.
* System 1 and system 2**: The brain uses two systems of thought: system 1, which is fast and intuitive, and system 2, which is slower and more analytical. System 1 comes into play most often, particularly for quick decisions, but system 2 can be called upon for more in-depth analysis if necessary. System 1 is energy-efficient, but can mislead us and lead to cognitive biases. **Confirmation bias is an example of a system 1 trap**.
* Subjective continuity**: The brain creates an impression of continuity in our autobiographical memory, even though there is no material proof of this continuity. We have the impression that we have always existed since we were born, but we cannot always back up this idea with evidence.
* Cerebral plasticity**: The brain's ability to change and restructure itself throughout life, known as cerebral plasticity, is fundamental to this process of reconstruction. Learning modifies the brain's structure and neuronal connections. Repeating and reactivating experiences strengthens neuronal connections.
* Emotions**: Emotions play an important role in our interpretations of the world and the way we experience things. The hippocampus and prefrontal cortex are involved in emotions, which help to guide decision-making.
* Brain imaging**: Brain imaging gives us the illusion of seeing the brain in action, but certain areas may be activated without this representing all brain activity.
In short, the brain's reconstruction of reality is a dynamic and active process that depends on our perceptions, knowledge and experiences, with an element of hallucination controlled by our brain. **The brain creates models to understand the world, but these models can be influenced by our preconceptions and emotions**. Although this reconstruction enables us to operate effectively in our environment, it can also mislead us and distort our vision of reality.

 

 The reptilian brain does not exist


The concept of the ‘reptilian brain’ is a simplification of brain function that was popularised by Paul MacLean's triune brain model in the 1960s. This model suggests that the human brain developed in three evolutionary stages, each associated with specific functions:
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The reptilian brain: responsible for instinctive behaviour.
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The paleomammalian (or limbic) brain: responsible for emotions and motivation.
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The neomammalian brain (or cortex): responsible for advanced functions such as language and reasoning.
Although this model has had some success, it is widely rejected by the scientific community because it oversimplifies brain development and fails to take account of the complexity of evolution.
In particular, the idea of a ‘reptilian brain’ is controversial and not a scientifically valid concept. It is important to note that although the brain can be divided into major parts that play a role in learning abilities, there is no region of the brain specifically dedicated to instincts and so-called ‘reptilian’ behaviour.
The brain is a complex, interconnected system, where different regions work together to perform cognitive functions. Emotions, motivation, attention, memory and decision-making are the result of interaction between different areas of the brain, not specific, isolated brain areas. For example:
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The cortex, the outer layer of the brain, plays a key role in the execution of actions and the perception of the environment. It is involved in memory, attention, engagement and learning from mistakes.
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The limbic system, in the centre of the brain, plays a key role in memory and the processing of emotions generated by engagement, learning by error and punctually attention.
In addition, research suggests that learning processes involve changes in the connections between neurons and the formation of new synapses. Brain activity is characterised by the functional connectivity between different structures involved in learning.
It is therefore essential to consider the brain as a dynamic and complex organ rather than a structure divided into areas with specific and distinct functions. The focus should be on understanding the mechanisms underlying learning, rather than on the idea of a ‘reptilian brain’.