Neurons: Nature’s Computing Machines

Neurons and how they work

We said earlier that animal brains puzzled scientists, because even small ones like pigeon brains were vastly more capable than digital computers with large quantities of electronic computing elements and storage space running at frequencies much faster than fleshy, squishy natural brains.

Because of this, scientists began paying attention to the architectural differences between the two kinds of brains. Traditional computers processed data sequentially and in fairly exact concrete terms. There was no fuzziness or ambiguity about their calculations. Animal brains, on the other hand, although apparently running at much slower rhythms, seemed to process signals in parallel, and fuzziness was a feature of their computation. Let’s look at the basic unit of a biological brain—the neuron.

Neurons, although there are various forms of them, all transmit an electrical signal from one end to the other—from the dendrites along the axons to the terminals. These signals are then passed from one neuron to the next. This is how our body senses light, sound, touch, heat, and so on. Signals from specialized sensory neurons are transmitted along our nervous system to our brain, which itself is mostly made of neurons.

The sketch below is the neurons in a pigeon’s brain, made by a Spanish neuroscientist in 1889. We can see the key parts—the dendrites and the terminals.

Neurons vs. computers

How many neurons do we need to perform interesting, more complex tasks?

Well, the very capable human brain has about 100 billion neurons! A fruit fly has about 100,000 neurons and is capable of flying, feeding, evading danger, finding food, and many other fairly complex tasks. This number, 100,000 neurons, is well within the realm of modern computers to try to replicate. A nematode worm has just 302 neurons, which is positively miniscule compared to today’s digital computer resources. But that worm is also able to do some fairly useful tasks that traditional computer programs of much larger size would struggle to do.

So what’s the secret? Why are biological brains so capable, given that they are much slower and consist of relatively few computing elements when compared to modern computers? The complete functioning of brains and consciousness is still a mystery, but enough is known about neurons to suggest different ways of doing computation, that is, different ways to solve problems.