SciBar #27: The Inside Story of the Brain

10 September 16 words: Gav Squires
The event that sees all the clever clogs put their heads together to talk science... in the pub...
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The final Wednesday of the month brings SciBar to the Vat and Fiddle and the speaker at August's event is Dr Federico Dajas-Bailador from the University of Nottingham to talk about "Making and breaking connections: The inside story of the brain"

But first we get a quick history of the brain. As far back as the seventeenth century BCE, an Egyptian battlefield surgeon was writing about the brain on papyrus – the first evidence of humans writing about the brain. However, the Egyptians didn't consider the brain to be an important organ – they weren't kept after mummification.

In the fourth century BCE, Aristotle considered the brain to be a cooling agent for the heart. At this time, the heart is considered to be a much more charismatic organ. In the third century BCE, Alexandrian anatomists provided a general description of the nervous system and they started to realise the impacts of brain injury.

By the second century CE, Galen had concluded that mental activity takes place in the brain. The ventricles in the brain were considered to be the important part as it was believed that these were somehow related to the four humours of the body - blood, yellow bile, black bile and phlegm. In the middle ages, the brain was thought to have three divisions – imagination, memory and reason. The fifteenth century brought the renaissance and brain dissections became much more common. They were hoping to find the sensus communis – the seat of the soul. Even Leonardo da Vinci was dabbling with brains.

The sixteenth and seventeenth centuries brought the anatomical works of Vesalius, Willis and Steno. They realised that the tissue was important not just the ventricles. Ramon y Cajal was really at the forefront of the birth of modern neuroscience in the late nineteenth century. He had wanted to be an artist but his father made him study medicine.

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By this time, a technique had been developed that allowed the staining of neurons and while the success rate of this technique wasn't very good, it did allow people to see neurons and realise that they weren't just a mass of cells. Using this technique, Ramon y Cajal was able to make drawings of neurons and the nervous system. He depicted the structure of the brain and he even predicted the flow of information in the brain. He realised that the brain is a composition of neurons and that they're individual but making connections.

Neurons are made up of dendrites, cell bodies and axons. They receive information at the dendrite and cell body level and it flows into the axon. A simple neuron makes connections and starts to look like a circuit. The ability to build these networks enables the brain to work. The axons can branch so that a neuron can make multiple connections.

We have both grey and white matter in our brains. The grey is where the cell bodies of the neurons reside. Your brain is trying to pack a lot of neurons into a very small space. White matter is around half of your brain and is made up of axons from the neurons. We need to understand both types of matter to see how neurons connect throughout the brain.

How do neurons connect? There are huge amounts of axon pathways and circuits are constantly being made – this explains the plasticity of the brain. The frontal lobe has more of these connections and more connections means more processing power. At twenty years old, you have around 176,000 kilometres of axonal connections in your brain.

As you get older, you start to lose this connections and so, by the time that you're eighty, you have 97,200 kilometres of connections on average. You lose around 10% of these connections every decade and as you lose these connections, you lose the flexibility to learn new things.

At twenty, your connections are fully formed but you have narrowed down the potential of your brain. The connections are moulded by your environment, which is an evolutionary advantage, to fulfil the needs of the brain. However, we are still not sure why you lose the connections as you get older.

Neurons in your body can grow up to a metre in length and can sense their environment to grow in a particular direction. To grow they use fast axonal transport – RNA is sent from the cell nucleus to the end of the axon where it is synthesised into protein.

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Federico and his team are interested in modelling neurons and they are now using a new technique called involving a three channel chamber, which means that more complex models can be created and also allows the modelling of reflex. In humans, acute pain is very useful but chronic pain is an indication that there has been the failure of a neuron somewhere.

Chronic pain is a massive issue in health and the three-channel chamber technique allows much better ways of investigating this. They are also running projects looking at how axons are lost since axon loss precedes neuron death. Could this be the first signs of the onset of Alzheimer's?

Since we can grow axons in a petri dish, why can't we put these into a brain? Why can't we recreate those connections? It's because we cannot recreate the conditions that brought the brain to the stage where it made those connections. We can't make the neuron be young again and so we cannot recreate the complicated network. A more important question is, how can we protect neurons before they start to die? How do we identify markers for things such as Alzheimer's in a cheap, non-invasive way so that we can try and do something about it before it actually happens?

Finally, since we're in a pub, Federico also talks about whether beer can kill brain cells. The bad news is that in a culture, beer is toxic to brain cells (nicotine on the other hand is neuro-protective) However, the increase in dopamine in the brain is probably worth it! Plus, alcohol will kill you because of damage done to the rest of your body before it kills the brain.

SciBar returns to The Vat and Fiddle on Wednesday 28 September at 7.30pm where Dr Ed Daw from the University of Sheffield will talk on "First direct detections of gravitational waves with LIGO"

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