[questionposter]

How do you get consciousness from no consciousness? You can't. That's why molecules and atoms and particles themselves have to contain less than a single unit of consciousness.
A single cell is the smallest singular unit of consciousness, but, 0+0 doesn't equal 1. Things like .5+.5=1, or .25+.25+.25+.25=1. But, this is pretty easy logic and it might help explain why quantum physics is so weird which is why I think it's been thought of before, so is there official quantitative any measurements of consciousness for things less than a single cell? I mean I know people who still think viruses are living things at least partially, but they're way smaller than bacterium even.

Is there even a name for this type of thing in science? Like maybe micro-consciousness or something?

This post has been edited by questionposter: 27 September 2011 - 01:09 AM

[Ringer]

Define consciousness.

[questionposter]

Ringer, on 27 September 2011 - 01:21 AM, said:

Define consciousness.

Dictionary.com has multiple definitions here.

http://dictionary.re...e/consciousness

I don't know what it is exactly in science myself, all I know is that biology, specifically from multiple textbooks, seems to define single cells carrying a single unit of it, so one cell contains a single unit of consciousness. But it would also make sense for some of the things is quantum mechanics, specifically the things that depend on the mere measurement of something.

There's also stuff like IQ and the quantitative measurement of intelligence and thinking capacity, but I'm not a big fan of those because we don't know exactly what intelligence is or exactly why and how thinking is the way it is.

This post has been edited by questionposter: 27 September 2011 - 01:29 AM

[Ringer]

I've never seen a biology book say single celled organisms have a unit of consciousness; not saying yours doesn't but I would like to see the specific passage in context. My point was that there isn't a good scientific definition of consciousness. There isn't a quantitative way to measure consciousness because all we have is a loose concept. It is one of those things that people generally assume is something very specific, but can't define. Intelligence is an entirely different concept from consciousness, so IQ and things are not a measure of any sort of consciousness.

[Phi for All]

!

Moderator Note

Thread moved to Psychiatry and Psychology from Evolution, Morphology and Exobiology.

[questionposter]

Ringer, on 27 September 2011 - 01:43 AM, said:

I've never seen a biology book say single celled organisms have a unit of consciousness; not saying yours doesn't but I would like to see the specific passage in context. My point was that there isn't a good scientific definition of consciousness. There isn't a quantitative way to measure consciousness because all we have is a loose concept. It is one of those things that people generally assume is something very specific, but can't define. Intelligence is an entirely different concept from consciousness, so IQ and things are not a measure of any sort of consciousness.

I don't have the text books anymore, it was a while ago and I just remembered these questions, but they were around 800 pages and it was called "Biology", and a few said something close to or exactly as "...a single cell is the smallest single unit of consciousness..."

And sure, intelligence is different, but not only do we not really understand how that works still, there's literally millions of factors and we don't completely understand how most of those fit in with everything in the brain. If I don't get enough sleep, I have the IQ of a clinically mentally retarded person. If I get a lot of sleep and eat well, I have an IQ higher than Einstein.

This post has been edited by questionposter: 27 September 2011 - 03:02 AM

[PhDwannabe]

Quote

How do you get consciousness from no consciousness? You can't.

Depending on what you mean by this--it's a pretty vague statement--at least 7 billion pieces of empirical evidence would seem to suggest that you, uhh, can, actually.

Quote

all I know is that biology, specifically from multiple textbooks, seems to define single cells carrying a single unit of it, so one cell contains a single unit of consciousness.

I have never, ever come across a scientific text which defines "cells" as a "unit" of "consciousness." Certainly consciousness is a phenomenon that seems to be produced by physical brains which are made up of cells (I'm trying my best to avoid sticky philosophy of mind issues here, though I can't even say that without asserting some kind of generally physicalist position), but that doesn't in any clear sense make cells themselves a "unit" of consciousness. Combustion often occurs when some carbon source is given access to heat and oxygen. Would it make sense to say that "carbon is a unit of combustion?" No.

Quote

intelligence is different, but not only do we not really understand how that works still

Ehhh, we kind of do, actually. Though nobody who knows something about it would put it that way. Our findings don't take the form of articles called "How Intelligence Works."

Quote

If I don't get enough sleep, I have the IQ of a clinically mentally retarded person.

No, you don't.

Quote

If I get a lot of sleep and eat well, I have an IQ higher than Einstein.

No, you don't.

[Greg Boyles]

questionposter, on 27 September 2011 - 01:08 AM, said:

How do you get consciousness from no consciousness? You can't. That's why molecules and atoms and particles themselves have to contain less than a single unit of consciousness.
A single cell is the smallest singular unit of consciousness, but, 0+0 doesn't equal 1. Things like .5+.5=1, or .25+.25+.25+.25=1. But, this is pretty easy logic and it might help explain why quantum physics is so weird which is why I think it's been thought of before, so is there official quantitative any measurements of consciousness for things less than a single cell? I mean I know people who still think viruses are living things at least partially, but they're way smaller than bacterium even.

Is there even a name for this type of thing in science? Like maybe micro-consciousness or something?

I once heard an excellent analogy of consciousness in a medical doco.

Noise and speed are not physical components of a motorcycle. And yet a motorcycle is specifically designed to generate these things when it is operating.

In the same way consciousness is not a physical component of the brain that can be pinpointed. But the functioning of the brain is designed to generate consciousness because gives the organism a survival advantage.

Therefore your logic is flawed. Consciousness is no more a physical component of individual cells or atoms than it is of the brain as w hole.

[questionposter]

PhDwannabe, on 27 September 2011 - 01:32 PM, said:

Depending on what you mean by this--it's a pretty vague statement--at least 7 billion pieces of empirical evidence would seem to suggest that you, uhh, can, actually.

Well, uhh, no, we don't, there's also equivalent pieces of evidence suggestion we don't because not only do we not understand how all those pieces fit together exactly, we don't even fully understand the pieces themselves. If the text books aren't accurate somehow, then we don't know either as far as this forum knows. It's like arguing for or against the existence of god.

PhDwannabe, on 27 September 2011 - 01:32 PM, said:

I have never, ever come across a scientific text which defines "cells" as a "unit" of "consciousness." Certainly consciousness is a phenomenon that seems to be produced by physical brains which are made up of cells (I'm trying my best to avoid sticky philosophy of mind issues here, though I can't even say that without asserting some kind of generally physicalist position), but that doesn't in any clear sense make cells themselves a "unit" of consciousness. Combustion often occurs when some carbon source is given access to heat and oxygen. Would it make sense to say that "carbon is a unit of combustion?" No.

Wait, when did I say consciousness was physical? But also, how does something have more consciousness than something else? How is something more conscious than another thing if consciousness its not quantitative?

PhDwannabe, on 27 September 2011 - 01:32 PM, said:

Ehhh, we kind of do, actually. Though nobody who knows something about it would put it that way. Our findings don't take the form of articles called "How Intelligence Works."

No, I wouldn't say we do a lot. We know somewhat about what can atoms do, but we don't know a lot about what makes them up or why they are they way they are. There's so many factors and the processes of the brain are so complex that you can't define the brain of an organism based on intelligence or IQ even though they seem to encompass a wide variety of thinking capabilities and operations of a brain.

PhDwannabe, on 27 September 2011 - 01:32 PM, said:

No, you don't.


No, you don't.

Well, it was more of an exaggeration, but that's just one factor, and yet how that one factor varies seems to greatly effect things like memory and cognitive thinking. http://nymag.com/new...951/index1.html

I mean I would agree we have some progress, but we are thousands of years from being able to just download martial arts into people's brains.

Greg Boyles, on 27 September 2011 - 03:51 PM, said:

I once heard an excellent analogy of consciousness in a medical doco.

Noise and speed are not physical components of a motorcycle. And yet a motorcycle is specifically designed to generate these things when it is operating.

In the same way consciousness is not a physical component of the brain that can be pinpointed. But the functioning of the brain is designed to generate consciousness because gives the organism a survival advantage.



Therefore your logic is flawed. Consciousness is no more a physical component of individual cells or atoms than it is of the brain as w hole.

I'm still not seeing where I said consciousness is a physical thing. All I said is I saw some text in some biology books that quantified consciousness. Time isn't physical, but you can quantify it. Energy is a physical thing in of itself, but you can add up energy or subtract it anyway. Consciousness could easily be a "result", but that's the same as adding the answers of "1+1" and "2+2", which gives a definitive real number of "6".

I'm pretty sure I didn't misread the text books, but what else could it have meant?

This post has been edited by questionposter: 27 September 2011 - 10:47 PM

[Greg Boyles]

questionposter, on 27 September 2011 - 10:38 PM, said:

Well, uhh, no, we don't, there's also equivalent pieces of evidence suggestion we don't because not only do we not understand how all those pieces fit together exactly, we don't even fully understand the pieces themselves. If the text books aren't accurate somehow, then we don't know either as far as this forum knows. It's like arguing for or against the existence of god.



Wait, when did I say consciousness was physical? But also, how does something have more consciousness than something else? How is something more conscious than another thing if consciousness its not quantitative?




No, I wouldn't say we do a lot. We know somewhat about what can atoms do, but we don't know a lot about what makes them up or why they are they way they are. There's so many factors and the processes of the brain are so complex that you can't define the brain of an organism based on intelligence or IQ even though they seem to encompass a wide variety of thinking capabilities and operations of a brain.



Well, it was more of an exaggeration, but that's just one factor, and yet how that one factor varies seems to greatly effect things like memory and cognitive thinking. http://nymag.com/new...951/index1.html

I mean I would agree we have some progress, but we are thousands of years from being able to just download martial arts into people's brains.


I'm still not seeing where I said consciousness is a physical thing. All I said is I saw some text in some biology books that quantified consciousness. Time isn't physical, but you can quantify it. Energy is a physical thing in of itself, but you can add up energy or subtract it anyway. Consciousness could easily be a "result", but that's the same as adding the answers of "1+1" and "2+2", which gives a definitive real number of "6".

I'm pretty sure I didn't misread the text books, but what else could it have meant?

If you had a simpler motorbike with one cyclinder rather than 4 or if the motorbike had only one gear then the amount of speed it could generate would be less. The amount of speed that can be generated is proportional to the complexity and specialisation of the enigine etc.

In the same way a simpler brain generates a more basic consciousness than a more complex brain like ours. So there is undoubtedly a spectrum of consciousness across the animal world.

But the total absence of a brain, such as in a single cell, means that there is 0 consciousness rather than 0.001 consciousness. A single cell is not designed to generate consciousness.

In the same way a motorcycle seat or a piston does not contribute 0.001 to the speed of the bike. The complexity of the motorcycle components operating, as designed, is what generates speed.

In effect, you are trying to argue that consciousness is a physical component of living things that can be pin pointed, i.e. by stating that a single neurone from a human brain has 0.001 of the total consciousness. You are saying that 0.001 of total human consciousness resides in any given neurone.

But a neurone on its own is not designed to generate consciousness and contains 0 consciousness. It contributes to consciousness only when it is combined with billions of other neurones in a physical brain.

So you could fairly argue that a neurone within a brain contributes 0.0001 (or what ever) to the total consciousness of the brain. But if you take that neurone out and put in in a petri dish then it has or no level of consciousness at all.

This post has been edited by Greg Boyles: 27 September 2011 - 11:46 PM

[Ringer]

questionposter, on 27 September 2011 - 03:01 AM, said:

I don't have the text books anymore, it was a while ago and I just remembered these questions, but they were around 800 pages and it was called "Biology", and a few said something close to or exactly as "...a single cell is the smallest single unit of consciousness..."

And sure, intelligence is different, but not only do we not really understand how that works still, there's literally millions of factors and we don't completely understand how most of those fit in with everything in the brain. If I don't get enough sleep, I have the IQ of a clinically mentally retarded person. If I get a lot of sleep and eat well, I have an IQ higher than Einstein.

When was the last time you read these biology books? How are you at all sure they were talking about consciousness in the way you speak. Just saying it was a fairly large book that said biology on it doesn't mean anything. You still haven't given me a formal definition of consciousness so we can work out how it can be quantified, because it isn't as of now. A dictionary doesn't have formal definitions so don't link that again.

[granpa]

sometimes the whole is greater than the sum of its parts

http://en.wikipedia.org/wiki/Emergence

http://en.wikipedia....trong_emergence

This post has been edited by granpa: 28 September 2011 - 12:49 AM

[questionposter]

Greg Boyles, on 27 September 2011 - 11:29 PM, said:

If you had a simpler motorbike with one cyclinder rather than 4 or if the motorbike had only one gear then the amount of speed it could generate would be less. The amount of speed that can be generated is proportional to the complexity and specialisation of the enigine etc.

In the same way a simpler brain generates a more basic consciousness than a more complex brain like ours. So there is undoubtedly a spectrum of consciousness across the animal world.

But the total absence of a brain, such as in a single cell, means that there is 0 consciousness rather than 0.001 consciousness. A single cell is not designed to generate consciousness.

In the same way a motorcycle seat or a piston does not contribute 0.001 to the speed of the bike. The complexity of the motorcycle components operating, as designed, is what generates speed.

In effect, you are trying to argue that consciousness is a physical component of living things that can be pin pointed, i.e. by stating that a single neurone from a human brain has 0.001 of the total consciousness. You are saying that 0.001 of total human consciousness resides in any given neurone.

But a neurone on its own is not designed to generate consciousness and contains 0 consciousness. It contributes to consciousness only when it is combined with billions of other neurones in a physical brain.

So you could fairly argue that a neurone within a brain contributes 0.0001 (or what ever) to the total consciousness of the brain. But if you take that neurone out and put in in a petri dish then it has or no level of consciousness at all.

Energy isn't physical, but I can say an electron has exactly .525*10^-23 joules of energy. But how do you quantify complexity itself then too? I could make a bigger motorcycle engine that doesn't generate as much as a smaller engine. Or I could generate an engine with less parts that goes at the same speed as another energy with more parts.

Also, here's a link explaining individual cells themselves have consciousness. Just how it doesn't make sense that a brain is a single thing and has a single consciousness, it might also not make sense that a cell itself is a single thing, not that the articles suggest that, but I'm connecting that to the other part of the topic. Although with your complexity thing, individual particles have a less complex consciousness then? I mean particles do react to things, its just that they aren't living.

http://www.ucl.ac.uk/~regfjxe/aw.htm

"The argument I will develop is that both information and physical substrate problems point to one solution; that consciousness is a property of a cell, not a group of cells."


and another one

http://www.ucl.ac.uk...gfjxe/awnew.htm

Ringer, on 28 September 2011 - 12:16 AM, said:

When was the last time you read these biology books? How are you at all sure they were talking about consciousness in the way you speak. Just saying it was a fairly large book that said biology on it doesn't mean anything. You still haven't given me a formal definition of consciousness so we can work out how it can be quantified, because it isn't as of now. A dictionary doesn't have formal definitions so don't link that again.

I distinctly remember the text from 2 years ago. I'm not completely sure it was talking about it that way, which is why I brought it up here. I didn't know there was a way to quantify consciousness, but I remembered things saying that individual cells had consciousness too and there's a bunch of weird stuff in quantum mechanics where particles seem to act as if they "know" whats going on but only in simple manners, so it makes some sense
"consciousness" probably doesn't have a formal definition in the same sense "the universe" doesn't have a formal definition. We can look at what we think it is or its properties are, which seem to be awareness of its environment in things which contain an abundance of it or some kind of acting on its own, and it's complexity can seem to vary among different organisms. It also seems to be what a lot of people label as "self awareness", but I don't have any idea how you could ever quantify that or really even measure that. How do we actually know an ant can't chose something?

I guess that's another possible definition, the ability to make a choice. I still don't know how to quantify that. When do you draw the line between a choice and just acting on instincts?

This post has been edited by questionposter: 28 September 2011 - 02:53 AM

[Greg Boyles]

granpa, on 28 September 2011 - 12:49 AM, said:

sometimes the whole is greater than the sum of its parts

http://en.wikipedia.org/wiki/Emergence

http://en.wikipedia....trong_emergence

EXACTLY. And deliberately so.

You could precisely replicate the full details of a motorbike out of wood rather than metal etc.

But would it generate speed? Would it be greater than the sum of its individual wooden components?

Clearly no!

questionposter, on 28 September 2011 - 02:45 AM, said:

Energy isn't physical, but I can say an electron has exactly .525*10^-23 joules of energy. But how do you quantify complexity itself then too? I could make a bigger motorcycle engine that doesn't generate as much as a smaller engine. Or I could generate an engine with less parts that goes at the same speed as another energy with more parts.

But that would need to result from deliberate research and design. You can't just make any old changes to a motorbike at a whim and expect it to run as normal or at all.

questionposter, on 28 September 2011 - 02:45 AM, said:

Also, here's a link explaining individual cells themselves have consciousness. Just how it doesn't make sense that a brain is a single thing and has a single consciousness, it might also not make sense that a cell itself is a single thing, not that the articles suggest that, but I'm connecting that to the other part of the topic. Although with your complexity thing, individual particles have a less complex consciousness then? I mean particles do react to things, its just that they aren't living.

NO!

Consciousness is not a physical component of a brain.

A neurone IS a physical component of a brain.

By arguing that a neurone contains a proportion of the total consciousness of a full brain you are arguing that consciousness can be pinpointed in a physical component of the brain. And in effect that consciousness itself is a physical component of the brain.

I believe that it is well established in neuroscience that this is simply not the case.

Consciousness results from functioning of a brain alone and not from substance of the brain - the neurones.

When normal brain function is interupted, e.g. when you get a severe blow to the head, consciousness ceases as you pass out.

Perhaps what is preventing you from getting your head around this is the implications it has for 'the self', its lack of 'permanence' and dissolution upon death.

This post has been edited by Greg Boyles: 28 September 2011 - 10:11 AM

[Mystery111]

Ringer, on 27 September 2011 - 01:43 AM, said:

I've never seen a biology book say single celled organisms have a unit of consciousness; not saying yours doesn't but I would like to see the specific passage in context. My point was that there isn't a good scientific definition of consciousness. There isn't a quantitative way to measure consciousness because all we have is a loose concept. It is one of those things that people generally assume is something very specific, but can't define. Intelligence is an entirely different concept from consciousness, so IQ and things are not a measure of any sort of consciousness.

Exactly! In fact, I've heard quite the opposite, that consciousness requires every cell the human body is composed of, not only the brain (Candice Pert, nuerobiologist).

Bottom line is, there is no part of the brain which we can pin-point and call the origin of consciousness. It is a sum collection of all the dynamics in our brain and the collective nervous system most likely.

[granpa]

machines know 'how' to do things but dont know 'what' they are doing.
animals know 'what' they are doing but dont know 'why' they do them
human beings know 'how', 'what', and 'why' they do things.

computers today only know 'how' to do things but dont know 'what' they are doing
to know 'what' they are doing they need 'logic programming'.
http://en.wikipedia....gic_programming
http://en.wikipedia.org/wiki/Prolog

awareness is simply knowing 'what' you are doing
self-awareness is simply awareness of awareness

[questionposter]

Greg Boyles, on 28 September 2011 - 08:55 AM, said:

But that would need to result from deliberate research and design. You can't just make any old changes to a motorbike at a whim and expect it to run as normal or at all.

But that's exactly how new motorbikes are developed in the first place.

Greg Boyles, on 28 September 2011 - 08:55 AM, said:

NO!

Consciousness is not a physical component of a brain.

A neurone IS a physical component of a brain.

By arguing that a neurone contains a proportion of the total consciousness of a full brain you are arguing that consciousness can be pinpointed in a physical component of the brain. And in effect that consciousness itself is a physical component of the brain.

I believe that it is well established in neuroscience that this is simply not the case.

Consciousness results from functioning of a brain alone and not from substance of the brain - the neurones.

When normal brain function is interupted, e.g. when you get a severe blow to the head, consciousness ceases as you pass out.

Perhaps what is preventing you from getting your head around this is the implications it has for 'the self', its lack of 'permanence' and dissolution upon death.

Saying something is quantified doesn't automatically make it a physical thing. There's plenty of non-physical things that can easily be quantified. Time can be quantified. Energy can be quantified. Gravity can be quantified. Intelligence can be quantified.

granpa, on 28 September 2011 - 05:12 PM, said:

machines know 'how' to do things but dont know 'what' they are doing.
animals know 'what' they are doing but dont know 'why' they do them
human beings know 'how', 'what', and 'why' they do things.

computers today only know 'how' to do things but dont know 'what' they are doing
to know 'what' they are doing they need 'logic programming'.
http://en.wikipedia....gic_programming
http://en.wikipedia.org/wiki/Prolog

awareness is simply knowing 'what' you are doing
self-awareness is simply awareness of awareness

Do bacterium know "what" they are doing? Do ants even know "what" they are doing? How do you know? How do you definitively know computers don't know "what" they are doing? Living things are made from things that just have chemical reactions, definitive chemical reactions that have specific causes and specific outcomes. This is the same as a computer except instead of chemical reactions it's 1s and 0s. An input is a chemical reaction and an output is another chemical which causes some reaction which causes another reaction, yet there's still plenty of consciousness.There's already evidence to suggest something can know "what" it's doing even though it's made from things that don't really know "what" they are doing as much in the first place. Computers would basically mimic that of a less complex consciousness. It seems to be exactly the same as how some other plants/animals act.

This post has been edited by questionposter: 29 September 2011 - 12:16 AM

[Greg Boyles]

granpa, on 28 September 2011 - 05:12 PM, said:

human beings know 'how', 'what', and 'why' they do things.

I don't know about that granpa!

I think a greater deal (than we are collectively prepared to admit to ourselves) of what we humans do is driven by subconscious instincts and impulses.

Why does a problem gambler gamble away his pay cheque and then steal money from his boss to chase his/her losses despite knowing that the long term consequences will be severe?

Why do some males give into temptation and commit adultry despite the risk of losing their family and home?

This sort of behaviour is clearly not driven by rational logic.

I could give you many other examples.

questionposter, on 29 September 2011 - 12:08 AM, said:

Do bacterium know "what" they are doing? Do ants even know "what" they are doing? How do you know? How do you know computers don't know "what" they are doing? Living things are made from things that just have chemical reactions, definitive chemical reactions that have specific causes and specific outcomes. This is the same as a computer. An input is a chemical reaction and an output is another chemical, yet there's still plenty of consciousness.There's already evidence to suggest something can know "what" it's doing even though it's made from things that don't really know "what" they are doing as much in the first place.

Intelligence is not quantified by determining the number of neurones you have in your brain.

If a neurone contains 0.00X% of the total consciousness then logically the number of neurones a person has determines the level of consciousness they have.

That is just silly.

A person who has had a stroke that affects the left side of their body would therefore have less consciousness than a normal person.

Again that's just silly and demonstrably not true.

The level of consciousness can be affected by a stroke depending on what part of the brain is damaged.

A stroke that affects the motor cortex or the visual cortex is unlikely to have any noticeable effect on a persons consciousness or personality.

However a stroke that affects the frontal lobes is extremely likely to have a noticeable effect on a persons consciousness or personality.

Ever heard of the brain injury patient Phineas Gage? Google him and find out what happened to him.

While not the precise location of 'the self' the frontal lobes are extremely important in its gensis. And any damage to this region of the brain severely degrades and damages 'the self'.

The hippocampi in each temporal lobe are heavily involved in laying down long term memory - they are equivalent to the reading/recording head of a computer hard disk. Any damage to these regions also degrades 'the self' since each of us are partly the sum of our memories and experiences.

So again, it is the complex interactions of these brain regions that generate 'the self' and consciousness.

While it can no doubt be quantified to some extent through memory and cognitive tests and the like, individual neurones alone have nothing to do what ever with that level of consciousness. It is about how well integrated and functional theses critical regions of the brain are.

This post has been edited by Greg Boyles: 29 September 2011 - 12:43 AM

[granpa]

the brain is a fractal pyramid.

it divides into 3 parts (midbrain, cerebellum, and cerebral cortex)
each of which divides into 3 parts (input, output, and processor)
each of which likewise divides into 3 parts and so on and so on.

this probably continues right down to neurons.



the cerebellum is concerned with 'how' to do what we do.
the cerebral cortex is concerned with 'what' to do.
the midbrain is concerned with 'why' we do what we do.

This post has been edited by granpa: 29 September 2011 - 12:40 AM

[Ringer]

granpa, on 29 September 2011 - 12:39 AM, said:

the brain is a fractal pyramid.

it divides into 3 parts (midbrain, cerebellum, and cerebral cortex)
each of which divides into 3 parts (input, output, and processor)
each of which likewise divides into 3 parts and so on and so on.

this probably continues right down to neurons.



the cerebellum is concerned with 'how' to do what we do.
the cerebral cortex is concerned with 'what' to do.
the midbrain is concerned with 'why' we do what we do.

That is unbelievably oversimplified. Mainly you will separate the brain into temporal, frontal, auditory, and occipital lobes. Within those will be many different parts. They are not necessarily input, output, and processor. And there are different types of neurons. Not to mention the glial cells.