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examBoard: AQA
examType: GCSE
lessonTitle: Basic Brain Development
Your brain is the most complex organ in your body. It weighs about 1.4 kg (roughly the size of a cauliflower) and contains around 86 billion nerve cells or neurons. But how did it get that way? Your brain didn't just appear fully formed - it developed gradually from before you were born and continues to develop throughout childhood and adolescence.
Key Definitions:
Did you know that a newborn's brain is about 25% of its adult size, but by age 3, it has grown to 80% of adult size? The brain develops more rapidly during the first few years of life than at any other time. During this period, more than 1 million new neural connections are formed every second!
Understanding how the brain develops helps us know why early experiences are so important. It explains why certain periods in development are crucial for learning specific skills and why some effects of early experiences might be difficult to reverse later in life.
Before we dive into how the brain develops, let's get familiar with its basic structure. The brain has several key regions, each with specific functions:
The largest part of the brain, divided into two hemispheres. It controls voluntary movements, speech, thinking, reasoning, memory and sensory processing.
Located at the back of the brain, it coordinates muscle movements, maintains posture and helps with balance.
Connects the brain to the spinal cord and controls automatic functions like breathing, heart rate, blood pressure and swallowing.
Brain development begins just a few weeks after conception. Here's how it unfolds before birth:
The foundations of the brain and central nervous system are established during this critical period:
During this period, the brain becomes more complex:
This is a period of remarkable brain growth and development:
Research has shown that high levels of stress during pregnancy can affect brain development. In one study, children whose mothers experienced significant stress during pregnancy showed differences in brain areas related to emotional regulation and had higher rates of behavioural problems. This highlights how environmental factors can influence brain development even before birth.
Although the basic structure of the brain is formed before birth, development continues rapidly after birth and throughout childhood:
The brain doubles in size in the first year. This growth is largely due to the development of synapses and the growth of glial cells (which support and protect neurons). By age 2, a child's brain has about 100 trillion synapses - more than they will have as adults!
The brain undergoes "pruning" - eliminating unused connections while strengthening frequently used ones. This process is guided by experiences and makes the brain more efficient. Language areas develop rapidly and the prefrontal cortex (responsible for planning and self-control) continues to mature.
During brain development, there are specific time windows when particular abilities are most readily developed:
These are strict time windows when certain types of environmental stimulation are necessary for proper development. If the stimulation is missing during this period, the related function may never develop normally.
Example: Vision development has a critical period. If a child has a visual impairment that isn't corrected during early childhood, the visual cortex may not develop properly, leading to permanent vision problems.
These are time windows when the brain is especially responsive to certain types of experiences, but development can still occur outside these periods, just with more difficulty.
Example: Language acquisition has a sensitive period. Children learn languages most easily before puberty, but adults can still learn new languages, just typically with more effort and less native-like proficiency.
Studies of children raised in Romanian orphanages in the 1980s and 1990s provided tragic but valuable insights into early brain development. These children received minimal social interaction and stimulation. Brain scans later showed reduced brain activity and volume, particularly in areas related to emotional regulation and attachment. Children adopted before age 2 showed better recovery than those adopted later, supporting the concept of sensitive periods in brain development.
Brain development is influenced by both genetic factors (nature) and environmental experiences (nurture):
Genes provide the basic blueprint for brain development, determining the general structure and timing of developmental processes. Genetic factors influence the production of neurons, their migration and the formation of basic circuits.
Environmental experiences shape how genes are expressed and how neural connections form. Experiences strengthen some connections while others are pruned away. Nutrition, social interaction, stress and learning opportunities all influence how the brain develops.
Several factors can influence how the brain develops:
Based on what we know about brain development, here are some ways to support healthy development:
A famous study by researchers Hart and Risley found that by age 3, children from higher-income families had heard about 30 million more words than children from lower-income families. This "word gap" correlated with differences in vocabulary size and later academic achievement. This research highlights how everyday interactions can significantly impact brain development and emphasises the importance of talking, reading and singing to children from birth.
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