measuring the human brain

[eruheru]

is there a way to measure the memory size of the brain?

[Green]

We might count the number of synapses, guess their speed of operation, and determine synapse operations per second. There are roughly 1015 synapses operating at about 10 impulses/second [2], giving roughly 1016 synapse operations per second.

A second approach is to estimate the computational power of the retina, and then multiply this estimate by the ratio of brain size to retinal size. The retina is relatively well understood so we can make a reasonable estimate of its computational power. The output of the retina--carried by the optic nerve--is primarily from retinal ganglion cells that perform center surround computations (or related computations of roughly similar complexity). If we assume that a typical center surround computation requires about 100 analog adds and is done about 100 times per second [3], then computation of the axonal output of each ganglion cell requires about 10,000 analog adds per second. There are about 1,000,000 axons in the optic nerve so the retina as a whole performs about 1010 analog adds per second. There are about 108 nerve cells in the retina and between 1010 and 1012 nerve cells in the brain , so the brain is roughly 100 to 10,000 times larger than the retina. By this logic, the brain should be able to do about 1012 to 1014 operations per second (in good agreement with the estimate of Moravec, who considers this approach in more detail

Memory and brain capacity is basically judged by A>the state of the neurons i.e healthy.unhealthy(due to smoking,booze,drugs.etc.)

B>how mmuch the person being meassured actually challenges his brain..

It has been a common belief that the brain deteriorates with age but this is actually false ..if you can challenge your brain enough for eg.think about philosophy,quantitative reasoning,try learning a new trade.

. here is an article about the computational limits of the human mind:

http://www.

merkle.com/brainLimits.html

[joema]

is there a way to measure the memory size of the brain?

See discussion in this thread: http://www.scienceforums.net/forums/showpost.php?p=236371&postcount=25

[bunburryist]

Your question implies a couple of assumptions –

1. That memories are “stored” in brains.

2. That whatever the nature of the reality underlying memory and mind, it can be measured.

 

• If the scientific theory of the senses is correct, you cannot locate the brain your memories are supposed to be “stored” in. Since, according to that theory, every aspect of your world experience is something happening in a material brain, what you have learned to call “your body” is not your material body, but rather an aspect of a brain-generated experience. Therefor, your material brain is not in what you experience as your head. Therefor, you cannot locate the material brain in which your memories are supposed to be “stored.” If you, in your experience, believe your memory/mind is happening in what you experience as your head, you either do not understand, or do not believe in, the scientific theory of the senses.

• No on ever discovered a memory stored in a brain.

• People "know" that memories are "stored in the brain" for the same reason they used to "know" that light was the vibration of the ether – because the fashionable worldview will not permit any other possibility.

• There is no legitimate theory of how memories could be stored in a brain. (Stylish computational speculation does not count for a legitimate theory.)

• There is no way to define A memory, since it cannot be isolated from the overall experience of remembering.

• Memory is typically discussed in terms of "data." Try to fit a musicians memory (melody, tempo, all the instruments parts, etc. - which is very holistic and spatial) of a whole symphony into any contemporary theory of memory. This whole “memory bit” business is just speculation. They get away with it because we are all used to this terminology and used to the belief in computational theories of mind.

• We have no way to even conceive of how many “memories” (we should say “how much memory”) we have, much less measure or quantify them/it. Think of all the places you can recognize (from many perspectives), how many faces, how many songs, movies, tv shows, stories, ……. No matter how many neurons we have (and no, they don’t connect), we don’t know that there would be enough to “store” all of our memory. Since we don’t know how a memory REALLY would be stored in a brain (if it REALLY was), we shouldn’t use numbers of synapses as a measure of how many memories could be stored unless we are sure we are holding up big, fat speculation signs.

 

It never seems to occur to many people that our simplistic, computer analogy brain-mind theory might simply be wrong. Not that there isn’t a relationship between the brains in our experience and our mind/experience/memory, but rather that the relationship between brains in our experience and our experience as a whole might be something we has you cannot conceive of. We really need to be more open minded with this.

 

Another thought – you will find that many people who are into computational theories of memory/mind are mathematicians first, and wonderers of mind second. These computational theories of mind and memory are not unlike string theory, in that they are very abstract, usually incomprehensible to the non-believer (and hence lend themselves as good tools of intimidation of non-believers), and really have no concrete relationship to reality.

 

Once again – I am not saying there is no relationship between brains in our experience and our experience as a whole – simply that we don’t know that it is the computational (or any other) version.

 

The position I can't help but find myself taking is that there is a fundamental problem with the materialist worldview (I am not a spiritualist type, either) that is at the core of many of our problems - brain-mind, brain-memory, particle-wave, separate neuron-holistic experience, etc.

[bascule]

It never seems to occur to many people that our simplistic, computer analogy brain-mind theory might simply be wrong.

 

The brilliant mathematician Roger Penrose, perhaps most famous for The Road to Reality : A Complete Guide to the Laws of the Universe (which is an excellent book btw, at least in my layman's opinion), wrote an entire book dedicated to this subject, Shadows of the Mind.

 

See: http://www.amazon.com/gp/reader/0195106466/ref=sib_rdr_next3_ex3/104-8421323-1959914?%5Fencoding=UTF8&p=S00O&ns=1#reader-page

 

Not that there isn’t a relationship between the brains in our experience and our mind/experience/memory, but rather that the relationship between brains in our experience and our experience as a whole might be something we has you cannot conceive of. We really need to be more open minded with this.

 

As a materialist I find this absurd.

 

Another thought – you will find that many people who are into computational theories of memory/mind are mathematicians first, and wonderers of mind second. These computational theories of mind and memory are not unlike string theory, in that they are very abstract, usually incomprehensible to the non-believer (and hence lend themselves as good tools of intimidation of non-believers), and really have no concrete relationship to reality.

 

Daniel Dennett wrote Consciousness Explained in which he developed an empirical theory of mind, based off a number of cognitive science experiments. He is, first and foremost, a philosopher. I don't think he particularly likes math. He's also a materialist.

 

Once again – I am not saying there is no relationship between brains in our experience and our experience as a whole – simply that we don’t know that it is the computational (or any other) version.

 

Well, artifical life/biomodelling will put that to rest. If we make a computational model of the human, and it exhibits all of the properties we would ascribe to human consciousness, then the door would be shut on dualist propositions forever.

 

The position I can't help but find myself taking is that there is a fundamental problem with the materialist worldview (I am not a spiritualist type, either) that is at the core of many of our problems - brain-mind, brain-memory, particle-wave, separate neuron-holistic experience, etc.

 

What is the problem?

[joema]

...Therefor, your material brain is not in what you experience as your head. Therefor, you cannot locate the material brain in which your memories are supposed to be “stored.” If you, in your experience, believe your memory/mind is happening in what you experience as your head, you either do not understand, or do not believe in, the scientific theory of the senses.

Your sensory input is physically stored in your brain as memories. We don't yet understand the exact bimolecular storage mechanism, but it's obviously of a physical nature -- damaging the physical brain or affecting it with physical drugs causes biological changes that affect memory.

 

No on ever discovered a memory stored in a brain...

This would require a relatively complete understanding of the physical storage mechanism, which we don't yet have. Therefore not "discovering" memories in the brain is simply stating the current limited knowledge level. It doesn't mean that will never be discovered. In 1950 we hadn't discovered what was on the surface of Venus, but that didn't mean it would never be discovered.

 

People "know" that memories are "stored in the brain" for the same reason they used to "know" that light was the vibration of the ether – because the fashionable worldview will not permit any other possibility.

Memories are obviously stored in the brain -- where else would they be? When ailments occur that affect the physical brain (Alzheimer's, etc), this affects memory. When you take substances that affect the physical brain (caffeine, etc) this affects memory.

 

There is no legitimate theory of how memories could be stored in a brain. (Stylish computational speculation does not count for a legitimate theory.)

There are many theories of memory storage, just as there are many theories of cosmology. Continued research and experimental evidence will determine which are ultimately most correct.

 

Memory is typically discussed in terms of "data." Try to fit a musicians memory (melody, tempo, all the instruments parts, etc. - which is very holistic and spatial) of a whole symphony into any contemporary theory of memory.

While the popular press often uses the simplification of the brain as a computer, and memory as data, researchers understand the brain is different. However you can obviously fit abstract items such as musician's memory into physical storage. Just because we emotionally perceive a holistic and spatial aspect to this doesn't mean it is, or that it can't be physically stored.

 

E.g, not long ago many people felt a computer could never beat the world's best chess player. The same reasoning was invoked -- humans think holistically in complicated strategies, etc. People considered their complex feelings and thought processes when playing chess, and reasoned a computer could not possibly reproduce those. Yet a computer has now beat the world's best human. So what if it uses brute force or different underlying machinery -- the final result is what counts. Likewise there's no reason to doubt a sufficiently advanced computer could store complex items like musician's memory.

 

We have no way to even conceive of how many “memories” (we should say “how much memory”) we have, much less measure or quantify them/it.

We can easily conceive our possible memory capacity -- we simply can't yet verify these conceptions. The original post starting this thread just asked can memory size be measured, hence it's appropriate to discuss what is known about that.

 

Think of all the places you can recognize (from many perspectives), how many faces, how many songs, movies, tv shows, stories, ……. No matter how many neurons we have (and no, they don’t connect), we don’t know that there would be enough to “store” all of our memory.

The physical brain obviously stores your memories, otherwise you wouldn't be having them. Your memory is obviously affected by physical brain changes such as disease, drugs, etc, showing the storage is physical in nature. We don't yet know the exact storage mechanism, but that doesn't mean no such mechanism exists. E.g, we don't yet know the physical mechanism of inherited lower animal "instinct", but it obviously exists -- ants dig tunnels without being taught, and this knowledge is somehow physically encoded into a single cell at conception.

 

we shouldn’t use numbers of synapses as a measure of how many memories could be stored unless we are sure we are holding up big, fat speculation signs.

Nobody is definitively saying synapses measure how many memories can be stored. The brain obviously has far greater memory capacity than the number of synapses. Yet synapses may be somehow related to memory capacity, and some theories discuss that possibility.