A controversial debate between two brilliant scientists led to an amazing discovery. Camillo Golgi in the 1800s looked at the brain through a microscope with a special stain he invented. This special stain gave a clear view of neurons and their parts. After looking, Golgi theorized that all neurons are one big continuous family, there are no gaps between neurons and they send electricity through each other back and forth. It was a revolutionary theory and Golgi was very confident in it. Near the same time in Madrid scientist Sanitago Ramon y Cajal took a better look at the brain through a microscope. Cajal theorized that each neuron is a basic unit that interacts with other neurons by contacting each other rather than being one continuous stream.
So who was correct? At the time there was evidence supporting both theories.
The development of a better microscope 50 years later allowed us to settle the debate. With this better microscope we were able to see that there was a space between neurons, therefore they were in contact and not continuous with each other. Thus proving that Cajal’s theory was correct!
Both scientists, Cajal and Golgi, were awarded the 1906 Nobel Prize for their contributions to neuroscience. However, it was a controversial ceremony as both scientists were not fans of each other and criticized each other, even within their Nobel Prize speeches!
The Synapse
This small gap between neurons, discovered by Cajal, is called the synapse.
To communicate with each other through the synapse, neurons use special chemicals called neurotransmitters. Your body has 100s of different types of neurotransmitters that help send different types of information.
When an electrical signal from the axon reaches the axon terminal, it triggers the release of neurotransmitters into the synapse. The neurotransmitters then move across the synapse and onto the next neuron’s dendrites.
Picture it like this, there are two pirate ships near each other and they want to send out a message. One pirate ship puts the message in a cannonball and fires it to the next ship. The next ship receives the message and then decides what to do with it.
Building and Sending
How are neurotransmitters released?
Neurotransmitters are made inside a neuron. They are then gathered together into pouches called vesicles. When a neuron is activated, the vesicles go to the end of the cell and release these neurochemicals into the synapse.
How do neurotransmitters send messages to the next neuron’s dendrites?
Different types of neurotransmitters have different shapes and sizes. To make sure the next neuron knows what message it is receiving it needs to know what neurotransmitter is touching it. You don’t open the door to your house to receive a message without knowing who’s knocking. To do this neurons use receptors. All receptors have a unique shape that fits only a specific type of neurotransmitter. With such a specific shape each receptor only accepts the chemical it knows.
Imagine you are a specific receptor. When you hear a knock, you look through the door keyhole and recognize the shape of your mom’s face. Now you open the door. However, unlike you, one receptor type can only recognize one type of chemical. If you were really like a receptor you would only open the door for your mom, nobody else.
There are three categories of neurotransmitters;
Excitatory - These tell the next neuron to get excited and fire a signal. Go, go go!
Inhibitory - Tell the next neuron to not fire.
Modulatory - These spread and out and can affect many neurons at a time. They also influence the effects of other messengers.
Within these three categories there are a variety of neurotransmitters that send different messages. For instance, different types can make you sleepy, happy or affect your memories.
Types of Neurotransmitters
Let’s take a look at some very famous neurotransmitters;
Rawr! There’s a lion right in front of you! Immediately your brain kicks into fight or flight mode. Will you run away or will you fight? What's causing this feeling? Adrenaline. Adrenaline increases the flow of blood to your muscles, raises your heart rate, and dilates your pupils all to keep you alert and ready in a fight or flight situation.
Similar to adrenaline, noradrenaline increases your alertness, blood pressure, and affects your decision making and focus.
“I’m walking on sunshine! Oooh and its time to feel good!” Dopamine is the pleasure neurotransmitter. It is an addictive reward chemical that your brain loves! Dopamine also helps with focus, concentration, memory, sleep, mood and motivation.
Serotonin is linked to your wellbeing and happiness. It helps balance your mood and plays an important role in sleep.
GABA regulates muscles tone and calms down your brain by reducing the rate neurons fire at.
Acetylcholine regulates our heart rate and blood pressure. It also plays roles in muscle contractions, memory, sleep, and learning.
Glutamate is the most abundant neurotransmitter in your brain. It plays a key role in functions like thinking, learning and memory. No wonder we have a lot of it, we are thinking everyday!
Ouch! If you feel pain endorphins work to make you feel less intense. Thank you endorphins.
Oxytocin is known as the love hormone, it is essential for making you love people. Like this baby:
Neurotransmitters are chemicals that send information from one neuron to the next through the synapse. We have got numerous different neurotransmitters each with unique tasks. The main categories are excitatory (GO), inhibitory (STOP), and modulatory neurotransmitters. From Golgi and Cajal debates to today we have learned tons about our synapses and the neurotransmitters that move through them, however, there are still plenty of mysteries left to uncover.
Now let's release some dopamine and dance!
Because you're a neurotransmitter pro!
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