A High Level Overview Of The Brain Part 2 - Neurons, How Information Travels
Tags: brain human
December.14.2009
In the previous brain article (A High Level Overview of the Brain) I explored the different parts of the brain and explained their responsibilities on a high level. Beyond that, I also went into a bit of detail on how information flows throughout the nervous system and specifically the brain. With that as an introduction of sorts, I want to explore some of this information flow in a bit more detail.
** Some of this may be a repeat from A High Level Overview, but there is also a lot of new information that was not previously included. The main topic here will be an extension of "The Flow Of Information" section.
Neurons - The Basic Unit of the Brain
The basic unit of the brain is the neuron. As stated in the previous article, a neuron is a nerve cell that sends and receives electrical signals over a long distances within the body. There are three parts to a neuron. These are the soma (cell body), dendrites (or dendrite tree), axons, myelin sheath, and terminal buttons.| Soma | This is cell body of the nerve. |
| Dendrites | They get signals from other neurons. There are two types of dendrites, expiatory and inhibitory. |
| Axons | Axons are the end bulbs that contain the neurotransmitters that send the impulse across the synaptic gap to another neuron, a neuromuscular junction, or a target cell of a gland. |
| Myelin Sheath | The insulating envelope of myelin that surrounds the core of a nerve fiber or axon and facilitates the transmission of nerve impulses. |
| Terminal Button | Small knobs at the end of an axon that release chemicals called neurotransmitters |
Now that we have an idea of what a neuron is, we can explore the three different types of neurons and what each is responsible for.
Sensory - These typically have a long dendrite and short axon, and carry messages from sensory receptors to the central nervous system.
Motor - These have a long axon and short dendrites and transmit messages from the central nervous system to the muscles (or to glands).
Interneurons - Found only in the central nervous system where they connect neuron to neuron.
How Neurons Work
Neurons fire and transport information throughout the body much like a serious of transistors within a computer. That could also be stated the other way around, but for purposes of this discussion, the given example will do. Neurons "encode" intensity by the frequency of firing and the speed at which they fire. Neurons are connected and essentially "talk to one another". This "talking to" relation is handled chemically (often times it is thought that this relation is electrical).Between neurons, there are gaps known as synapses. When a neuron fires, an axon sends chemicals through this gap via the synapse. These are neurotransmitters and they affect the dendrites. The chemicals cause an increase or decrease in firing with each scenario having a different outcome. An increase would be classified as an excitatory neuron while a decrease is know as an inhibitory neuron. The firing rates and sequence in which they happen can produce an infinite number of results and varied outcomes.
Much like hacking a piece of software, psychopharmacological drugs can manipulate these types of neurons and speed up and slow down each type to hopefully obtain a desired result. There are two ways this happens. Agonist drugs speed up the firing rate of neurons while antagonists slow down the amount of neurotransmitters.
These neurons and neurotransmitters act much like a combination of a massive distributed computer network as well as a parallel computer environment. There is "talking" and exchanging of information that, as mentioned above, could produce an infinite number of results. There is shared memory and private memory aspects that all work together to create "something".
The Brain / Computer Comparison
I have made quite a few references as to how the brain is like a computer. Actually, I would say that the computer is more of an extension of the brain. Much like the wheel and other tools of that sort were created to ease physical work for humans, the computer is essentially a tool for assisting with mental tasks that humans are not strongly suited at doing quickly and/or repetitively. With that, there is a high correlation between the two. For future writings, it will help if there is an understanding of both the computer and the brain.While the computer is very fast at number crunching and calculations, there are aspects of the brain in which the computer still cannot compete. One of these areas is the idea that the brain is highly resistant to damage. If you damage a computer by dropping it or some other form of damage of that sort, there is a good chance that it will need to be replaced. In extreme cases, this is the same for the brain, but there are also circumstances where the brain can suffer a reasonable amount of damage and continue on. It is known that different parts of the brain can take over for other parts in certain instances. The one caveat of this is that it is easier a young brain to do this. As we age it becomes more difficult for the brain to make new connections. There are some things that can aid in this though. A balanced diet filled with Omega 3 fatty acids as well as challenging your brain daily by learning something new or playing stimulating games are two excellent ways to keep new connections forming and your brain young and "fresh".
Another way the brain is better than a computer is its ability make sense of the outside world. The computer is good at doing calculations and following a logical progression that has been defined and programmed for it. The brain has the ability to interpret the outside world and thus come up with new ideas. It may be safe to say that at this point that computers are still followers whereas humans are leaders because we are the "thinkers" behind the technology. This may change in the future as technology catches up with biology.
It is important to understand that we understand how computers work. Humans built them. We still have a LONG way to go towards having a complete understanding of the brain. The computer has only been around for a short time. The brain has had approximately a 100,000 year head start on the brain. The reason I am making this comparison at this point is because we have learned much about the brain since of the advent of computers. In the future, our knowledge will increase with the assistance of computers. Eventually these machines may take over as the new leader in intelligence. For now, we study the brain and try and replicate its functions in the digital world. It is the template for where we want our technology to go in the future.
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