Or that is what scientists first thought.
When glia were first discovered, they were dismissed as passive filler cells. But more recently there has been a shift in thinking. A shift that is in part driven by measuring the numbers of the different types of cells in the brain.
Although the number of glia and neurons is generally at a ratio of 1:1 when you look across the whole brain, this changes when you look at the cortex. In your cortex – the part of your brain which makes sense of your surroundings, plans your actions, guides your decisions and makes you creative and flexible in your thinking – some estimates put this difference at a ratio of ~4 glial cells to every 1 neuron.
This got some neuroscientists thinking. Most notably scientists such as the late Ben Barres from Stanford University. They couldn’t quite believe that these cells simply played a passive role. Instead, they believed that they must be an integral and active part of the machinery which creates your thoughts, memories and mental flexibility.
And there is another interesting piece of trivia in this story. This comes from Einstein’s brain.
Because when researchers studied Einstein’s brain to see if there was anything special about it at an anatomical level, they were only able to discover one difference. This was that Einstein’s brain had a far greater number of glial cells than the control brains that they compared it against.
Although anecdotal, it is a piece of a growing body of evidence which shows that glial cells, and in particular a family of glial cell call astrocytes, provide more than just passive support to the neurons.
The astrocytic stars of your brain
In fact, the list of what these tiny cells do is quite remarkable. And growing. They help to regulate your brain’s energy reserves. They act as gatekeepers at your blood-brain barrier and control which substances can enter and exit your brain. And they influence the rate of blood flow around your brain.
All pretty fundamental processes for keeping your brain ticking over whilst you are going about your day.
But astrocytes also play an active role at the synapses of your brain – the chemical connections which join one neuron to another. And this means that they aren’t just there operating behind the scenes, they are busy at the frontline of your thinking.
This is because these synapses are the critical points in your thought pathways where the messages can be tweaked and adjusted before continuing on to their final destination. It is also where “neuroplasticity” – the dynamic process of updating the connectivity diagram of your brain in response to your life experiences – takes place.
Astrocytes are therefore essential for making sure that you are able to learn and remember, and for ensuring that you can adapt and stay flexible in the face of a fast-paced and evolving marketplace.
Speed and defence functions in the brain
But astrocytes are only one type of glia. You also have cells called oligodendrocytes. These insulate your neurons and help to ensure that signals can be rapidly sent along your neurons.
And microglia. These are in charge of your brain’s immune response and destroy any foreign agents that they come across, keeping your brain healthy.
Glia are also involved from the very first stages of your brain’s development, providing the scaffold along which the structures of your brain are built.
Rewriting the neurobiological models of mental illness
Given the critical role of glia in the brain it is therefore perhaps not surprising that scientists are increasingly turning to glia to try and understand a whole range of mental illnesses such as depression, anxiety, schizophrenia, ADHD, and addiction, to name a few.
And wouldn’t it be strange if our neurons, the electrical wires of our brain on which so much emphasis is placed, turn out to be the mental work-horses, and it is actually our glia that are running the brain.
Only time and many hours of dedicated research will tell.
A science that never stands still.
It is also an example of how the field of neuroscience, and therefore our understanding of the human brain, is constantly evolving. Every month there are new pieces to the puzzle of how we think, feel and behave.
A puzzle which helps inform us about how our brain works. And, more importantly, provides the groundwork for how we can make our brain work better.
If you would like to find out more about the what’s new in neuroscience and how it could be relevant to your organisation, then please get in touch with us at Synaptic Potential.