This week in what fills me with awe: Brains

Ever wondered why snowflakes are symmetrical? How does the water molecule adhering to the snow flake know where to land and which orientation to point so that it is symmetrical with the the far side? It comes down to electric charges. Water has an electric charge that is not balanced. The shape of a water molecule is kind of like a boomerang, with the hydrogen atoms at the far ends and the oxygen in the bend. The oxygen has a strong negative charge which equals and cancels out the positive charge of the two hydrogen atoms. But that equal is only at a distance. Close up one side of the boomerang is negative, the other side is positive, so long as you are coming in from the right view. This makes the water molecule susceptible to electrical and magnetic fields, kind of like how iron filings will fall into an interesting pattern when sprinkled around a magnet. The snowflake is basically a water version of that.

As each water molecule joins the snowflake, the shape of the field shifts a bit to factor in this new particle. It is a dynamic system, ever changing as bits join the snow flake. Snowflakes are mostly water, but they also capture bits of dust, pollen and other pollutants. This can radically change the way the snow flake “grows”.

After a team of sperm cells break through the outer membrane of an egg and one timely sperm gets in and fertilises the egg, the embryo begins a massive growth and divide cycle, increasing in size manyfold very rapidly. Each of these new cells are basically exact clones of the first egg/sperm hybrid cell. After a short amount of time, the egg/sperm cell division starts to create some different versions, which begin to self sort into clumps of like type cells. Slowly some basic organs and nerves begin to grow. Some differentiate into muscles and blood vessels. Some begin to differentiate into skin. Most of the skin cells form on the outside. As the parent cell divides, if it finds itself unbalanced due to being on the outside, the new cells become skin cells. Sometimes the skin cell forms accidentally on the inside. When this happens, it will try to migrate to the outside, and if it fails, it will self destruct and be recycled – that is, consumed by a nearby cell which then divides into a more useful inner body cell.

There are no brains yet.

The gonad cells appear around 4-5 weeks. Eventually these will become either testes or ovaries. At this point, it is too soon to tell. We don’t know why the gonads appear where they do, but we do know they go on a fantastic journey before settling down in their eventual place in about 59 out of 60 people. 

Around this time, the nerve cells have self organised into a network with a definitive spine and the first preliminary bulge at one end that could be considered the beginnings of a brain. This is not a brain. It is the hint of one.

By Dr. Vilas Gayakwad – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=9582575 – A six-week embryonic age or eight-week gestational age intact human embryo.

Somewhere around week 6 some of the muscle cells have divided into a specialised type that beats in a rhythm. This will eventually become a heart and be part of pumping blood. At this stage those, they just pulse. There is nothing overly special about this. If a doctor were to biopsy some of your heart tissue from your chest and put it in a nutrient bath, it will also pulse, completely separately to any external signal. Add another bit of heart tissue in the nutrient bath and they will beat out of sync from each other. When they get close enough, they self organise and start to beat in sync. Nothing special here, just the nature of that kind of cell.

The embryo at this stage is about 4mm long. The nerves are continuing to network all of the areas of the embryo together. Pre-arms and pre-facial features are starting to develop and the embryo looks like a very strange alien or fish spawn thing. 

At week 7, the growing clustered nerve ganglion at the top of the spine divides into 5 major regions and starts to specialise. This is similar to some of the earlier cells specialising into cell versus muscle. They are all nerve type cells, some are now looking more like synapses but there is no intrinsic control over the body yet per se. That is, each part of the body that was busy self organising into the things that make up a human are continuing to do so without a central instructing organ like a brain. They are working more like the snow flake, but at a much greater complexity. Each cell is emitting hormones and other communicative fluids, which attract other like kind cells. Based on rules, the cells will organise in specific but somewhat random ways similar to how a flock of birds or a school of fish will move together without a specific organiser.

The brain/nerve cells are self organising similar to how heart muscle cells self organise. In petri dishes we have witnessed synaptic cells joining together in networks and starting the rudiments of communication. There isn’t enough to have a thought, or memory or a dream, but there is some kind of organisation occurring. 

This growth keeps going. At about 20 weeks we get the first indication that the proto-brain of the fetus is responding to external stimuli. It is now plugged into enough of the fetus that it receives data from outside of brain for processing and then sends a signals back out to do something about that signal. One might be mistaken into thinking that thought is occurring now. It is possible, but the odds are more likely that it has some stimuli reflex that your lower spine does when you step on something sharp. Your foot lifts off the unexpected sharp thing before the signal can reach your brain. We don’t fight for the rights of our lower spine – it’s just a reflex mechanism with some basic data analysis without actual thought. It is like saying that your knee is capable of thought when you hit it with a reflex hammer and your foot kicks. It isn’t – it’s just a reflex.

Time goes on and the baby is born. Sometimes. Often the embryo grows faultily and is expelled before 4 weeks. Many fertilised eggs self abort because they aren’t viable and many pregnancies are not detected because of this. The uterus just gets ready for the next chance and doesn’t bother to inform the owner of the uterus that an egg was fertilised and rejected.

One third of the embryos that make it past 4 weeks don’t make it past 12 weeks. Many of these pass without notice too. 

Those what make it to live birth all have a brain. No two of these brains are the same, much like no two snowflakes are the same (allegedly this saying was tested and found that under certain circumstances you can get a duplicate snowflake around 1 in 100,000 – some people contest this). Humans are not snowflakes (leaving politics out of this). No two brains are the same. They generally look similar to a simple look, but the neurons and synapses do not conform to any rigid model. There are some organisational rules and principles that form specialised regions in similar locations, but the details are different.

For example, the bit of my brain that determines where my left index finger is going to be when I want to press the “a” key on my keyboard is located in a couple of hundred neurons in a part of the motor cortex of my brain. The odds are very high that you have a motor cortex in the same approximate region of your brain, and that the area that controls my left hand is about the same in yours. My left index finger control will be sort of similar to yours but importantly different. The cluster of neurons that allows my finger to strike the “a” key will be tellingly different to yours. And yet I can hit it quite well and the odds are high that you can do the same.

From a little before birth I have been training my brain to do a whole host of human things just as you have yours. But the details of how each of our brains do this is very different in specific, even if it is kind of similar in general. Somehow through all of this we are able to communicate, make art, create computers and send people into space. We are able to learn and teach each other skills.

If I were to take the bit of my brain that does a skill that I have and you don’t, and put it into your brain, it would mean nothing to your brain. It would not give you that skill. If I use that part of my brain to show you how to do the skill, you will form a new part of your brain, often coopting under used parts of your brain that are doing other things, to form a new pattern that is now your new skill, as per how I showed you. It won’t look like mine. It will probably be stored in a similar part of your brain to mine, or it may be in a very different part.

As we become adolescents, our brains switch from dependent child to independent adult over roughly a ten year period. This involves a massive reorganisation of the brain, vastly increasing the complexity as new wrinkles form, new connections are made and new skills are acquired. The hormones in our body trigger massive changes to our muscles, sex organs, height, hair and other bodily systems. 

While certain developmental stages can be predicted, the specific path is unique for all of us. Kind of like if I want to get some chips from the store, I’ll grab my keys, get in the car, drive to the store, find the chips, pay for the chips, drive home and then eat the chips. Assuming you don’t have chips in your reach you’ll go through a similar approximate process. However if you do it exactly the way I do, you’ll probably crash into furniture before you even get to your car, and should you drive exactly the way I did to get to the store, it will be bad. Instead, you’ll adapt the approximate system to your needs and your situation. Generally it will look the same, but specifically it will be different.

This gets interesting when we start looking at how brains work. We know that serotonin is an important neurotransmitter for certain tasks. When you have too much or too little it can look like anxiety and or depression. How much is too much or too little is determined by the individual symptoms of the person. I may be functioning fine, but if you have my levels you might be chronically depressed. We don’t have a set amount you are supposed to have – we have a range of “probably good” (not that we tend to bother measuring the amount, we just treat the symptoms). If the amount is a little out for you, then you’ll show a bit of behaviour that reflects that outness. If you are a lot out, you’ll exhibit strong symptoms. If you are very far out, you’ll have other problems.

This also makes it tricky when we are trying to define rules. Some people pick up implicit rules easily. Most pick them up easily enough. Some struggle a bit and some struggle a great deal. This is because all of our brains are different. There is no faulty neuron causing this, and probably no specific neurotransmitter. The odds are it is a shaping of the brain from birth (that’s what the science is currently telling us), which has the most likely origin in the DNA that the combination from the beginning formed – the sperm/egg cell. If your parents found it easy to pick up implicit (not clearly stated) rules, then you probably will too. If your parents struggled, you probably will too.

Basically, brains are awesome. I love that we all have different brains. I also find it kind of surprising how well we humans interrelate and interact considering these differences.

I also find it interesting when some people don’t accept that humans are a grouping of very different brains, or when people think there is something fundamentally wrong with their brain.

Different isn’t wrong as no two brains are the same.