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Asked by joebh1234 to Chris, Dave, David, Fiona, Jack on 20 Jun 2013.
Question: If our brains are simply made up of chemicals and neurones firing and stuff, then are we basically extremely advanced computers?
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Jack Miller answered on 20 Jun 2013:
Hi Joebh1234,
Excellent question! In short, I think the answer is yes!
Our brains are fantastically complex machines, but, on the face of it, their electrical activity seems rather simple. Each neuron has a set of inputs (from other neurons) and outputs (to other neurons). The number of inputs and outputs vary between neurons. Essentially, and this is very much a physicist’s view of what’s going on (biologically it’s more complicated), each neuron counts how many signals it receives from other neurons on its inputs. If that number is greater than some arbitrary threshold, it fires, and sends a signal on every output at once.
We have a very, very large number of neurons, with an astronomical number of connections (synapses) in our brains. Thought is an ’emergent phenomenon’ of having a large system like I’ve just described. There are many examples of these sorts of emergent behaviours, and the brain’s a really, really hard place to start, so let me describe a simpler example.
E. Coli are bacteria you’re probably familiar with (and might get to see under a microscope in biology lessons). They’re single-celled organisms, with no organelles inside their cell, and don’t have anything like a brain at all. Yet, if I put a load of E. Coli on one side of a slab of jelly, and a load of sugar on the other side, and came back the next morning, I’d find that all the E. Coli had decided to swim over to (and eat) the sugar. This is a phenomenon called chemotaxis — they’re moving (taxis) towards a chemical (sugar). They swim towards where the concentration of sugar is highest. Yet, how do they know where that is? The concentration of sugar is essentially constant around the bacteria, as they’re an awful lot smaller than the plate is.
The answer’s rather clever, and shows how a system of switches can produce this behaviour. E. Coli move by having a set of beating flagella, which spin (in one direction) to drive them forwards. If they spin the flagella in the opposite direction, they don’t go backwards but, because of the structure of the flagellum itself, tumble randomly in space. They also have a sensory complex that can ‘smell’ how much sugar is where they are at a given moment.
Ordinarily, in a plate with no sugar, E. Coli will swim forward for a bit, and then tumble randomly, before setting off in another direction, and, later, tumbling again. This makes them ‘diffuse’ out from where you put them, like a drop of ink on a piece of paper. If you add sugar into the mix, however, the probability that the E. Coli tumble is decreased proportionately to how much sugar they sense over a given time interval. So, if they’re swimming towards sugar, their sensors sense that they’re getting more sugar over a given time interval, and they’re less likely to tumble. The reverse is true if they’re swimming away, and the net result is lots of bacteria swimming towards food.
This is an example of how a random process with a simple switch can produce a complex behaviour. Our brains are unimaginably more complex, and lots of information is stored in a ‘layered’ fashion, on top of the patterns of neurons firing. Yet, I hope you can see how we might be able to produce complicated behaviours from sets of switches and random processes.
Trying to understand how our brains work is like trying to understand how to beat Mass Effect 3 by looking at the voltages on the printed circuit boards in your computer. I’m glad I’m not the one doing it!
If you’re feeling brave, a good book that looks at this problem in a lot more detail, with a lot more maths, is “Godel Escher Bach” by Douglas Hofstader.
Hope that helps!
— Jack
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David Freeborn answered on 20 Jun 2013:
The short answer is yes- the brain functions in a very similar way to digital computers. Both brains and computers are devices that work by storing information, manipulating symbols, and using that to perform calculations and make “decisions”. A computer does this through electronics: a series semiconductor “switches”, a brain does this by “electrochemical” neurons.
But brains are currently many, many, many times more powerful than even the best computer. The brain contains about 100 billion neurons, but unlike these computer switches, each neuron doesn’t just connect to two others. Each neuron has 1,000 connections, representing about 1,000 potential synapses. And each of these can have many, many different types of signal coming through it.
That means a brain could store a minimum of about 2.5 petabytes of data: the equivalent to 2,500 terabytes, or 2,500,000 Gigabytes: way better than even the best computers right now. It’s likely that brains are even better than this.To put it another way, brains are capable of computing over 6,000,000,000,000,000 computations every second. No digital computer can match that- yet!
The biggest difference between our brain and a computer isn’t just the power though. Computers, designed by humans, are very “modular” and “serial” in how they work. That means we get different parts of the computer to perform different functions. That’s by far the easiest way for humans to design something, but it limits what sort of ultra-complex things we can get the computer to do.
The brain has different modules like a computer, but a lot of processes take place across the whole brain. But higher processes are affected by the entire brain state in a very, very complex way. The entire brain is able to “feedback” and effect other parts of the brain, to create a level of symbols more complex than any part of the brain itself. So, you won’t ever be able to find specific “thoughts” in a specific part of the brain: the entire state of the brain is responsible for generating individual thoughts.
That’s one reason why brain damage can affect an entire person’s personality. One example of this is Phineas Gage, whose entire personality was changed when his brain was injured in an accidental explosion. You can read about him here: http://en.wikipedia.org/wiki/Phineas_Gage
It turns out evolution is still much better at creating complex computers like the brain than human beings are! In the future, the design of computers is going to try and incorporate elements of evolutionary processes in it: by introducing random chance and trying to select factors that work.
It might not be too long before humans do start to build computers that are as good as the human brain though: humans are getting better at building computers fast! If we look back at history, the computing power humans can build has been doubling every 18 months: this is a rule known as “Moore’s Law”. That means that computers about as powerful as human brains might be only 30 years away!
Comments
rajathjackson commented on :
I think that the reason we are not able to completely understand our brain is because its our brain. Like its difficult to look into the center of our own galaxy than any other because we are situated in our galaxy. Our brain is so complicated as it has understood a lot about the nature(at least a lot compared to other organisms). So, I think its natural that we are not able to understand our brain because our brain itself is studying it. But, its not that we are the top of the intelligence table. There may be other creatures(aliens) which may be more intelligent(much more advanced computers) than us. They might easily tell us about how our brain works like we do of other simpler organisms.