You contain billions and billions of neurons, and it’s just as well that you do, because they provide the communication paths for information to travel between the body and the brain and around the brain itself. Every time you move, feel the wind in your face, hear a voice, recall a memory, that information is moving along and between neurons.
So what are they? Neurons are extremely small cells, but they are not round and blobby like fat cells, nor are they neat and rectangular like the cells that line your stomach. Instead, neurons have a special shape that lets them do their job of conducting information. Scientists have now discovered more than 100 individual types of neurons in the human brain, and they come in various shapes and sizes, but there’s a basic pattern, so let’s take a closer look.
Neurons typically have extensions coming out of them – spiky bits that can essentially receive information. These 'receivers' are called dendrites, and they pick up a signal from the body or from other neurons within the brain. You could think of them as functioning like an aerial on a building and the building itself, the cell body or soma, is like mission control. The soma (mission control) is a really important structure because without it, the neuron dies.
Often the information is something the neuron has to pass on elsewhere – to another part of the brain or maybe out to a muscle in the body – therefore the information needs to travel.
Many neurons have a long, string-like part called the ‘axon’ – this is like a communication cable coming out of mission control that lets the neuron stretch across relatively long distances – some bundles of neurons, or nerves, go from your spine all the way down to your little toe! Axons in neurons within the brain aren’t quite so long, but they let regions of the brain ‘talk’ to each other.
In order to get the piece of information from point A to point B, an electrical signal travels along the axon. To help ensure the signal gets there, some axons are surrounded by a fatty sheath, which acts as an insulator – much like a plastic cable around electrical wires. And those signals can move fast – in some cases at around 120 metres per second! That’s pretty fast when you consider that a cheetah, the world's fastest animal, reaches speeds of 33 metres per second which is more than three times faster than the current 100 metre world record holder Usain Bolt.
At the end of the axon, the tip of the transmitting axon forms a junction with a receiver – often a dendrite of another neuron. At this point, we move from an electrical signal to a chemical signal. Chemicals, called neurotransmitters, are released when the electrical signal is received and pass across a gap between the sender and receiver called a synapse – like passing a note in class, but this is all legit, and note-passing neurons form a friendly kind of bond that strengthens their connection.
The neuron that receives the signal can further pass it along to other neurons in its network, and in this way information can travel rapidly around the brain. Or the neuron may stop the signal and so slow the information, which is another important function in the network.
So there you have it, that's how your brain communicates with itself and with the rest of your body: information moves from dendrites to the cell body and along the axon, from one neuron to another. In this way the billions of neurons inside your body form trillions of connections between them, and the signals that whizz and fizz through these networks allow you to do what you do.
The route a piece of information takes through neurons around your brain is called a pathway, and the more you use a pathway the more defined it gets. A bit like a well-trodden track through a field or forest – the more people walk on it, the easier it is for others to walk there too.
That's why when you learn something new – maybe you take up a sport, walk a new route to work or learn a new language – it can seem challenging, but as you repeat tasks you forge or 'wire' stronger pathways in your brain and they become second nature.
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