Is the Brain a Computer?

English: a human brain in a jar
English: a human brain in a jar (Photo credit: Wikipedia)

I’ve just read an interesting article by Robert Epstein which tries to debunk the idea that the brain is a computer. His main thrust seems to be that the idea that the brain is a computer is just a metaphor, which it is. Metaphors however are extremely useful devices that use similarities between different systems to perhaps understand the least understood of the two systems.

Epstein points out that we have used several metaphors to try to understand the mind and the brain, depending on the current state of human knowledge (such as the hydraulic metaphor). This is true, but each metaphor is more accurate than the last. The computer model may well be the most accurate yet.

Cork in a hydraulic ram
Cork in a hydraulic ram (Photo credit: Wikipedia)

The computer model may well be all that we need to use to explain the operation of the brain and mind with very high accuracy. Brain and mind research may eventually inform the computer or information technology.

It is evident that Epstein bases his exposition on a partially understood model of computing – for instance it appears that he thinks that data is stored in a more or less permanent fashion in a computer. He says:

The idea, advanced by several scientists, that specific memories are somehow stored in individual neurons is preposterous; if anything, that assertion just pushes the problem of memory to an even more challenging level: how and where, after all, is the memory stored in the cell?

This describes one particular method of storing data only. It sort of equates with the way that data is stored on a hard disk. On a disk, a magnetic bit of the disk is flipped into a particular configuration which is permanent. However, in the memory of a computer, the RAM, the data is not permanent and will disappear when the computer is switched off. In fact the data has to be refreshed on every cycle of the computer’s timer. RAM is therefore called volatile memory.

English: Several PATA hard disk drives.
English: Several PATA hard disk drives. (Photo credit: Wikipedia)

In the early days of computing, data was stored in “delay line memory“. This is a type of memory which needs to be refreshed to preserve information contained in it. Essentially data is fed in and read out of a pipeline simultaneously, the read out being fed back to input again to complete the cycle and maintain the memory.

I expect that something similar may be happening in the brain when remembering something. It does mean that a memory may well be distributed throughout the brain at any one time. There is evidence that memory fades over time, and this could be related to an imperfect refresh process.

Schematic diagram of a delay locked loop (DLL)
Schematic diagram of a delay locked loop (DLL) (Photo credit: Wikipedia)

Epstein also has issues with the imperfect recall that we have of real life objects (and presumably events). He cites the recall of a dollar bill as an example. The version of the bill that people drew from memory was very simplified as compared to the version that they merely copied.

All that this really demonstrates is that when we remember things a lot of the information about the object is not stored and is lost. Similarly, when an image of the dollar bill is stored in a computer, information is lost. When it is restored to a computer screen it is not exactly the same as thing that is imaged. It is not the same as the image as stored in the computer.

Newfoundland 2 dollar bill
Newfoundland 2 dollar bill (Photo credit: Wikipedia)

It’s worth noting the image file in a computer is not the same as the real thing that it is an image of, as it is just a digitisation of the real thing as captured by the camera that created the image.

The image on the screen is not the same as either the original or the image in the computer, but the same is true of the image that the mind sees. It is digitised by the eye’s rods and cones and converted to an image in the brain.

English: Stylized idea of the communication be...
English: Stylized idea of the communication between the eye and the brain. (Photo credit: Wikipedia)

This digitised copy is what is recalled to the mind’s eye when we remember of recall it. The remembered copy of the original is therefore an interpretation of a digitised version of the original and therefore has lost information.

Just as the memory in our minds is imperfect, so is the image in the computer. Firstly the image in the computer is digital. The original object is continuous. Secondly, the resolution of the computer image has a certain resolution, say 1024 x 768, and some details in the original object will inevitably be lost. More details are lost with a lower resolution.

Computer monitor screen image simulated
Computer monitor screen image simulated (Photo credit: Wikipedia)

In addition the resolution of the image stored in the computer may not match the capabilities of the screen on which it is displayed and may need to be interpolated which produces another error. In the example of the dollar bill, the “resolution” in the mind is remarkably small and the “interpolation” onto the whiteboard is very imperfect.

Epstein also assumes a particular architecture of a computer which may be superseded quite soon in the future. In particular in a computer there is one timing circuit, a clock, that all other parts of the computer rely on. It is so important that the speed of a computer is related to the speed of this clock.

Clock signal + legend
Clock signal + legend (Photo credit: Wikipedia)

It may be that the brain may operate more like a network, where each part of the network keeps its own time and synchronisation is performed by a message based scheme. Or the parts of the brain may cooperate by some means that we don’t currently understand. I’m sure that the parts of the brain do cooperate and that we will eventually discover how it does it.

Epstein points out that babies appear to come with built in abilities to do such things as recognise faces, to have certain reflexes and so on. He doesn’t appear to know that computers also have built in certain basic abilities without which they would be useless hunks of silicon and metal.

An American Megatrends BIOS registering the “I...
An American Megatrends BIOS registering the “Intel CPU uCode Error” while doing POST, most likely a problem with the POST. (Photo credit: Wikipedia)

When you switch on a computer all it can do is read a disk and write data to RAM memory. That is all. When it has done this is gives control to program in RAM which, as a second stage, loads more information from the disk.

It may at this stage seek more information from the world around it by writing to the screen using a program loaded in the second stage and reading input from the keyboard or mouse, again using a program loaded in the second stage. Finally it gives control to the user via the programs loaded in the second stage. This process is called “bootstrapping” and relies on the simple hard coded abilities of the computer.

English: grub boot menu Nederlands: grub boot menu
English: grub boot menu Nederlands: grub boot menu (Photo credit: Wikipedia)

But humans learn and computers don’t. Isn’t that right? No, not exactly. A human brain learns by changing itself depending on what happens in the world outside itself. So do computers!

Say we have a bug in a computer program. This information is fed to the outside world and eventually the bug gets fixed and is manually or automatically downloaded and installed and the computer “learns” to avoid the bug.

Learning Organism
Learning Organism (Photo credit: Wikipedia)

It may be possible in the future for malfunction computer programs to update themselves automatically if made aware of the issue by the user just as a baby learns that poking Mum in the eye is an error, as Mum says “Ouch!” and backs off a little.

All in all, I believe that the computer analogy is a very good one and there is no good reason to toss it aside, especially if, as in Epstein’s article, there appears to be no concrete suggestion for a replacement for it. On the contrary, as knowledge of the brain grows, I will expect us to find more and more ways in which the brain resembles a computer and that possibly as a result, computers will become more and more like brains.

Brain 1
Brain 1 (Photo credit: Wikipedia)

 

Time and time again


Embed from Getty Images

Well, this will be my third post in a row about time. I think I’ll discuss something else next week!

As I’ve said before, the path of a particle as it travels through space in the usual way can be represented as a line in a four-dimensional space-time system. There will be one and one line only that represents the history of the particle from the time it is created until the moment that it is annihilated. If we decide to plot only this particle’s location over time there will be no others lines in this space.

Diagram showing phase space plot of particle u...
Diagram showing phase space plot of particle undergoing betatron motion (Photo credit: Wikipedia)

The path will twist and turn as the particle is affected by fields and other particles. It may take a sudden turn when our particle collides with another particle. This interaction can be visualised by adding the data about the other particle to the same space-time graphs. However, since the particle is constantly jostled by other particles the diagram would quickly become crowded so to keep it simple let’s drop out the lines of all the other particles.

So we are back to the original single line we started out with. If we assume that it can’t time travel, there will be no loops and gaps in the line. In other words, for every time between its creation and destruction there will be one and only one set of three space coordinates. Of course the line will have curves and kinks as the particle interacts with other particles and fields.

English: The Markov chain for the drunkard's w...
English: The Markov chain for the drunkard’s walk (a type of random walk) on the real line starting at 0 with a range of two in both directions. (Photo credit: Wikipedia)

Suppose we allow choice into our system. Suppose we have two choices A and B. At the point that the choice is made (at a macro level), there are two possibilities for the space-time position of the particle. From that point on the particles history could be represented by an A line and a B line, which at first glance appears to contravene the single point rule. However by making a choice we are saying that either A will occur, OR B will occur, but not both, so we really have only one line.

A choice is not the same as travelling in time though, so let’s plot A AND B, and we will get a multiply branching tree of lines as the time line splits on every point where a choice is made.

English: Tree of choice for creative commons l...
English: Tree of choice for creative commons licenses. (Photo credit: Wikipedia)

The question arises as to which of these lines is the “real” life line of the particle. This we don’t know in advance because we don’t know what the choice will be, which leaves us in the uncomfortable situation of having something unpredictable happening and physics deals in things that can be predicted.

When a choice is made by someone, it is highly likely that one option is much more likely than the other. Maybe the probability is 0.8 to 0.2 (80:20 in percentage terms). Another way of looking at it is to say that, all other things being equal, if the choice were to come up 100 times, A would be chosen 80 times and B would be chosen 20 times. Of course in a 100 tests, it could be that the actual figures might be 79 and 21.

Brooklyn Museum - The Life Line - Winslow Homer
Brooklyn Museum – The Life Line – Winslow Homer (Photo credit: Wikipedia)

It would be highly unlikely that A would be chosen once and B chosen 99 times in 100 trials of course, but it remains possible. (We have to remember that the circumstances of the choice must be identical, that is, all other things being equal)

We could incorporate this into our system by adding a “probability” axis (running from 0 to 1, or equivalently to 0 to 100). A point on this axis would represent the probability of the choice that was made and the whole sheet represents the life of the particle.


Embed from Getty Images

It appears that two points on the line are axis, the ones at 0.8 and 0.2 are “special”. In the stated situation those at two probabilities of the outcomes A and B. The probability of any other outcome say Z are zero and effectively outcome Z does not exist.

All things being equal there appears to be no physical reason why someone would choose one option over another. It may be that, all things being equal, that one option gets chosen more often than the other, but the sum of all the probabilities is one – in other words it is absolutely certain that one of the options is chosen. I find this totally mysterious. A choice is an event where the outcome is not dictated by the prior history of the event and is decided by the person making the choice.

English: Figure 1. Demonstration of the decisi...
English: Figure 1. Demonstration of the decision space (Photo credit: Wikipedia)

However the person’s mind is making the decision, and the person’s mind is equivalent to the state of his/her brain and the state of his/her brain is determined by physics, chemistry and biology. I see no “wriggle room” to allow for a person to make a choice.

Can we solve this dilemma by introspection? Descartes looked within himself and concluded that “I think therefore I am“. I don’t know if Descartes intended or realised it, but the implication is that thinking, which happens in the mind/brain, occurs before consciousness. In other words, consciousness is an epiphenomenon of the mind, just as the mind is an epiphenomenon of the brain.


Embed from Getty Images

Why then do we think that we make choices and decide things? Well, by introspection I can look at any decision that I have made and I can always point at reasons why I made the choice. Well, of course this may be simple rationalisation. We look at the decision that we made we look at the reasons that might explain why we chose that course and we pick and choose the ones that we like.

While that may be the reasons that we give, and some of them may be true, I do believe that we have reasons for what we do, but those reasons are physical – the configuration of our brains, as a result of past events and happenings, results in a foregone conclusion – we perform an action which looks to the outside world like a decision.

Magnetic Resonance Imaging - Human brain side ...
Magnetic Resonance Imaging – Human brain side view. emphasizing corpus callosum. (Photo credit: Wikipedia)

For instance, if we are filling in a form and we are required to check a box, we “choose” the box depending completely on what has gone before. If the boxes are “Male” or “Female” we know what sex we are so naturally we would choose the correct box. No real decision is made. If we are annoyed at the form or we are in a joking mood we might tick the wrong box. It depends on our state of mind before making the decision what we do, and it depends only on that.

English: checkbox, check box, tickbox, tick bo...
English: checkbox, check box, tickbox, tick box Italiano: checkbox, check box, tickbox, tick box (Photo credit: Wikipedia)