A neuron is the technical term for what we laymen call a brain cell. These are the cells in the brain and throughout the nervous system that work together to create your thoughts and emotions.
They interpret the input from your senses – as forwarded by
messages from your eyes, ears, nose, mouth and sense of touch. They’re helped in this by the glial cells (glia is Greek for glue), whose sole function is to sustain and protect neurons.
Glial cells make sure that neurons do their job. It was the
Spanish scientist Santiago Ramón y Cajal (1852-1934) who first presented the idea of neurons to the world. This work won him the Nobel Prize for Medicine in 1906. It is impressive to see how closely his ink drawings of the nervous system, with which he clarified his research, match modern illustrations of neural networks.
How enlightening it is to peek into the brain and discover that there are things happening there that are strongly reminiscent of the internet! But actually, it’s the other way around. The internet’s network was inspired by the brain’s network, and it came about almost by chance. Details later. Let’s stick with the brain a little while longer.
Neurons work together to create the thoughts, feelings and perceptions that communicate what your senses are telling you.
This process is very much like what happens when you call someone from a cell phone. Here’s how:
It used to be commonly held that the central nervous system consists of tiny nerve fibres. But Ramón y Cajal proposed that it really consists of billions of gooey little grey cells called neurons.
He and his colleagues couldn’t be sure whether these neurons were connected to each other or not. But they were there, all right. Unfortunately, the technology needed to study neurons closely wasn’t available until later on in the 20th Century. But further research based on Ramón y Cajal’s theories proved that neurons actually did interact. What is even more interesting: it’s not just that they work together – but how they work together – that creates our thoughts, feelings and interpretations of information from our senses. Seen through a microscope,
neurons appear to be communicating with each other. They have a body (the soma), which contains the cell’s nucleus. This is where you find your DNA code and everything else that makes you who you are, look the way you look and predispose you to your palette of personal skills and attributes.
The soma itself looks somewhat like a chestnut, with little spikes or tentacles. These spikes, or tentacles, are called dendrites.
The cell’s “sender” is the axon, which resembles a spidery antenna protruding from the soma. Whenever you think or feel something, it’s because millions of neurons have started communicating with each other, firing off messages from one neuron’s axon to another neuron’s dendrite. These messages – untold billions of axon-dendrite transactions constantly sizzling through your body’s networks – are important. They consist of a series of commands for the receiving neuron, which is how the neuron “decides” what to do.
For instance, a baby smiles at you. Processing this incoming information, neurons begin shooting messages to other neurons, until millions of micro-orders merge to create a collective image.
Your system feels an emotion that makes you smile back at the child. If this reminds you of packet switching, it’s no coincidence.
This neural system parallels the way that the internet and cell phones work.
Imagine that your neurons are communicating via micro-tiny mobile phones. A transmitting neuron sends an electrical
impulse along its sender, the axon. This corresponds to it dialing a number from its cell phone, trying to contact another neuron.
When one neuron’s axon and another neuron’s dendrites get close to each other, and one neuron’s axon is loaded with the aforementioned electric impulse, then the two can communicate.
Bzzzt. Bzzzzzzt. Contact.
This electro-chemical buzz happens through a “phone central”
called the synapse. The synapse is the center between two neurons, like the digital central you pass through when trying to reach someone on the cell phone. But just dialing isn’t fun – it’s the conversation that matters, right? As in the case of the mobile phone, there is no physical contact between the neurons when they communicate. Instead there is a protein in the transmitting neuron which alters shape, and in turn causes lots of little containers to open up within the neuron. These little containers, or vesicles, contain the orders one neuron wants to send to another.
The packet of orders is called the neuro-transmitter and, just like the message you try to deliver using your cell phone, the neuro-transmitter plays a central role in brokering the conversation between neurons. It is the neuro-transmitter that tells the
recipient neuron what to do to help your mental process work as smoothly and elegantly as possible. But there’s nothing more annoying than trying to get an important message through during a call with a bad connection. We all know that frustrating “Hello?
Can you hear me?” which puts a stop to so many communications. Same thing with neurons.
If neuro-transmitter packets aren’t sent efficiently from one neuron to another, things go wrong in your brain.
Parkinson’s Disease is an example of a disease that stems from
“poor connections” between neurons that are trying to send the neuro-transmitter dopamine to each other. Bad connections when trying to communicate the neuro-transmitter seratonin can lead to depression. So it isn’t just in your everyday life that bad connections can cause trouble – this is also the case in your brain’s internal network of neurons.
As mentioned before, the “telephone exchange” where two neurons meet is called the synapse. But there is another way neurons can communicate, called the nexus. In this case, the surfaces of the two neurons actually do touch, thus creating a path for communication. In the telephone analogy this would correspond to a land line.
But whether the neurons connect via landline or via wireless connection is not important. What is important is to understand that they do connect. And, when they do connect, it’s thanks to a neural network that closely resembles the computer networks or mobile phone networks we use every day. They transmit many little commands which, via a network, become one big action.
When these networks light up, our thoughts come alive. Feelings emerge. And input from our senses is being processed. Imagine all this intricate communications among those little gooey grey neurons, creating a vast internally-connected network. This is called a neural network, and it is what inspired both Herbert Spencer and Sigmund Freud.