As you go through life, your body changes radically.

Inside your head, your most complex organ is constantly transforming too, beginning work before you're born, and continuing even after you've been declared dead.

This is the life cycle of your brain.

Your brain starts to form about two weeks after conception.

On one side of the developing embryo, the cells thicken to form what is called the neural plate.

Around week four, this folds over onto itself, forming a tube which ultimately creates the nervous system.

Every minute from the time the neural tube closes, your brain is growing hundreds of nerve cells called neurons.

At birth, your brain contains about 100 billion neurons, more than an adult.

This gives the baby the best chance of developing a healthy brain.

The excess neurons are shed before you become an adult.

But what you don't have is a lot of synapses, the point of contact where electronic signals are passed between neurons, which in turn change the behaviour of the neurons.

Some neurons become insulated by a fatty substance called myelin.

These neurons, known as white matter, are able to transmit information faster between brain areas, allowing more complex processes to take place.

When you're born, the average number of synapses per neuron is 2,500.

But that increases to approximately 15,000 per neuron over the first few years of your life, as your neurons mature and create new synapses.

The speed at which they form synapses could be one reason children find it easier to learn things like languages or musical instruments.

It's also why children's experiences in this phase can have lasting effects on their development.

From age 3 until about 10, your brain starts to remove connections it no longer needs.

Neuroscientists used to think all synapses worked at a constant, fixed level.

But now they understand that synapses can be strengthened or weakened depending on how they are used.

This is known as neuroplasticity.

It's essentially your brain's way of making sure it's more efficient with experience and absorbs new information.

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By the time you become a teenager, your brain has stopped growing, but it continues to develop.

The insulation of the neurons, which begins at birth, continues over many years.

It starts at the back of the brain and moves forward, so different parts of your brain develop at different rates.

Areas associated with reward, like the ventral striatum, develop faster than the prefrontal cortex, which is linked to self-control and rationality.

Teens also experience major changes in their limbic system, the part of the brain that controls emotions.

All this might explain why teenagers experience more mood swings than adults.

Neuroscientists believe the difference in development between the emotion-driven part of the brain and the rational part may also be the reason teenagers are more likely to take risks or experience addiction compared with adults.

Puberty also brings with it increased activity in the ventromedial prefrontal cortex, the part of the brain that relates to self-evaluation.

This change can improve teenagers' understanding of social interactions and their ability to form friendships.

But it might also make them more susceptible to social anxiety.

Post-puberty, the brain continues to develop.

Brain tissue in the prefrontal cortex increases connections, joining the emotional and motor centres.

Your brain reaches full development by your 30s, and white matter reaches the highest volume at about 40.

But it's not all downhill from there.

As you age, plasticity allows your brain to keep changing and adapting.

Research has shown older adults are more likely to use both sides of the brain for short-term memory, rather than just the left brain hemisphere.

Middle-aged brains have also learnt to minimise the negative.

Scientists have found the amygdala, the part of the brain that deals with emotion, lights up when younger people look at both positive and negative images.

But for older adults, it reacts much less when shown negative images.

This might be because as you age, you become more resilient.

Decades of experience in dealing with difficult situations activates neural pathways, which can be used when you experience a similar situation.

For those who go through the menopause, changes to the amount of estrogen affect brain energy consumption, producing symptoms like hot flushes and mood swings.

The volume of white matter also falls, and doesn't recover.

But despite this, those who are post-menopausal have higher structural connectivity between some brain regions than those who don't go through the menopause, meaning that the connections in those regions may become more efficient.

The point at which your brain begins to slow down depends on your genes, but on the whole, studies show that the slowing process begins in your 30s and 40s, before accelerating in your 60s and 70s.

As you move into later life, your cerebral cortex, which is the outer layer of the brain, thins.

This is particularly noticeable in the frontal lobe and the hippocampus, which are important for memory, emotions and navigation.

Your white matter shrinks, and the brain generates fewer chemical messengers, such as dopamine and serotonin, which leads to slower cognitive processing.

Until very recently, neuroscientists didn't know what happens to your brain when you die.

But by chance, doctors were recording the brainwaves of a patient when he died of a heart attack.

They found a change in a specific band of brainwaves involved in high cognitive functions, such as concentrating, dreaming and memory retrieval.

Suggesting that just before you die, your brain may recall important life events, which may explain why those who have near-death experiences report seeing their lives flash before them.

And your brain doesn't stop working, even when you're dead.

Some studies have found that brain activity may continue for several minutes, even after your heart has stopped.