Basic Neuroscience Series – Neurons

What is a neuron?

The central nervous system (the brain and spinal cord) is made up of two types of cells: neurons and glia. Neurons are crucial players in the brain, where they act as messengers. They are able to do this using electrical impulses and chemical signals to relay information throughout the brain and between the brain and the rest of the nervous system.

Neurons are made of three parts: a cell body, axon and dendrite. The cell body contains a nucleus, where the genetic material of the cell is found. Dendrites surround the cell body and receive messages for the cell, whilst the axon transmits messages from the cell.

Between the axons and dendrites of different neurons, chemicals (called neurotransmitters) can be passed across a synapse for them to communicate and relay messages. This is known as neurotransmission.

While there are 10,000 specific types of neurons in the brain, there are three main ones:

1. Sensory neurons: which carry information from sense organs to the brain (allowing you to see, for example).
2. Motor neurons: which carry information from the brain to the muscles (allowing you to speak, for example).
3. Interneurons: which includes all other neurons that convey information between other neurons.

How were neurons discovered?

The discovery of neurons involved a series of experiments throughout the 19^th century. Santiago Ramón y Cajal was an essential contributor to this discovery, hence why he is often nicknamed the Father of Modern Neuroscience. However, Ramon y Cajal built his intricate research on findings from Camillo Golgi, who had previously stained neurons using silver nitrate.

Eventually, in 1891 Wilhelm Waldeyer merged Ramon y Cajal’s research with the cell theory, as well as with ideas from Wilhelm His and August Forel, to form the ‘neuron doctrine’. This stated that the nervous system is made up of discrete cells, which Waldeyer named neurons. To this day, Ramon y Cajal’s intricate neuron drawings remain extremely insightful, showing the structural diversity of the brain and nervous system.

Want to learn more?

Here are some additional resources for you to explore:

• Here is an animated video from Neuroscientifically Challenged, explaining what a neuron is in 2 minutes:
  https://www.youtube.com/watch?v=6qS83wD29PY&ab_channel=NeuroscientificallyChallenged
• As well as a video from Khan Academy explaining the anatomy of a neuron: https://www.youtube.com/watch?v=ob5U8zPbAX4&ab_channel=KhanAcademy
• Lastly, here is a link to a BioNinja IB unit explanation, discussing all the basics of neurons and synapses: https://ib.bioninja.com.au/standard-level/topic-6-human-physiology/65-neurons-and-synapses/
  
  
  

Neuron history source: F. Jabr (2012), “Know Your Neurons: The Discovery and Naming of the Neuron”, Scientific American.

Featured image source: D. Nield (2018), “This Is The Most Complete Brain Map to Date, Showing Every Single Neuron in a Fruit Fly’s Brain”, Science Alert, NATURE.