(note that this is a voice to text translation of the video because we have lost the original script) 

Hello this is Curt doolittle for the propertarian institute.

And this is course 103 foundations and the topic is the nervous system.

It’s a topic i put a lot of work into.

You should find the results somewhere between novel and current.

And if i’ve been successful i’ll provide you with the explanatory power
most of us seek in our search to understand and describe the production of human experience

now in preparing for this talk of the nervous system we need to choose a degree of resolution that we can use to describe the nervous system from.

if we choose too low resolution say the molecular transmission of charges across a synapse we’ll understand the mechanics of that transmission without necessarily learning the function that it serves in the transmission of information.

So i’m going to limit our discussion to the degree of resolution we need to understand the function of the components of the nervous system which explains the transmission and transformation of information in operational terms. 

Now that said, i’ve included a list of videos in the lesson that go into greater
resolution or greater detail for those of you who find those subjects interesting and now this is a fairly long topic and consisting of series of videos.

It will take a bit of work to get through but hopefully you’ll enjoy learning about it as much as i did trying to make it learnable so to speak.

All right.

So the scope of this unit is an overview of the nervous system – about the flow of information through it. We’re going to cover some of the anatomy; but we’re going to cover only that anatomy necessary for describing this narrative we’re putting together.

We’ll talk about the functions of those components in the nervous system but in particular, the functions of neurons, the columns, the hypothalamus.

And I’m going to talk about how great we create maps of reality with those underlying functions and then a general explanation of how we make choices and produce memories. And at the end hopefully we’ll have the narrative or theory of how the brain and mind produce experience action and memory; this is part one, the anatomy.

The nervous system which we cover input, integration, calculation, memory and output. Well we’re going to start out with a nervous system overview which something most of us probably know about; the central nervous system consists of the brain and the spinal cord.

The peripheral nervous system is everything attached to that and it’s divided into two sections: the sensory or input, they call it afferent division; and the motor or efferent division or the output division.

The motor neuron system is divided into a couple of pieces: the autonomic nervous system which controls things like your heartbeat and your glands; the sympathetic division which gets you ready for fight or flight which is the excitatory division;

the parasympathetic division does the opposite, which calms you down and puts you at rest; and then lastly we have the somatic nervous system or the motor neurons which is the voluntary system.

The structure of the nervous system no matter where in it is approximately the same; it’s basically these neural tissue cells along the line function sort of like christmas light repeaters and there’s quite a bit of myelination on the outside which is an insulator which insulates them from damage but also prohibits degradation of the signal.

As a simple overview of the evolution of the brain there we see the at the bottom the embryo at one month at five weeks and then the child.

And as you can see we sort of looked like a fish at the beginning; you know a very primitive uh lizard in the middle; and we need to finally develop into the the mammal and the human at the end there.

We can see in the lower right hand corner the nervous system of a fish; forgive me if i can’t recall which one it is but you can see the spinal cord, you can see the cerebellum which is this little lump there and that cerebellum is what precalculates all of your physical motion.

A bit of the optic region where your vision is processed, the thalamus which regulates input, the purple area at the beginning is the cerebrum where what little thinking a fish does is processed, and the olfactory bulb which is kind of interesting because in all of us it’s the information that isn’t pre-processed.

Now pretty much everything else is pre-processed before it gets to us except sent but if you look at the left we have the cerebrum which is the large overlying layer which we’re going to talk mostly about, the cerebellum which i covered already, then the parts of the reptilian brain which regulate your body involuntarily, these regulatory or pre-processing functions are the medulla which connects the brain to the spinal cord and manages traffic between the cerebellum and the sabri cerebrum and manages some traffic between the cerebrum and cerebellum and it acts as the sort of control center for the autonomic functions specifically of the heart and lungs. And it regulates your digestion, breathing, you know things like sneezing, swallowing or even that wonderful thing we call vomiting.

The pons is next and it is a sort of preprocessor for the senses, particularly for the head; it’s the largest part of the brain stem. It’s a group of nerves that connect different parts of the brain together and they serve as a bridge between various parts of the nervous system including the cerebellum and cerebrum.

The pons also relay signals from the forebrain to the cerebellum and this helps organize involuntary actions like posture and equilibrium as well as some others that like respiration sleep bladder control, hearing tastes and eye movement.

A lot of your facial expressions and even the possibility of dreaming there’s an awful lot that goes on there that regulates what goes on in the head.

The midbrain helps control eye movement and processes visual and auditory information.

We’re going to see that vision is extremely complex and is spread across multiple areas of the brain – not only this area here but also the back of the brain, the visual cortex, the visual association area, and even eye movement that allows tracking is done on the very front of the brain.

Over on the upper right you can see that with this reptilian brain is purely instinctual, it’s things that prevent us from hurting ourselves because we have choice.

And people will call these the reptilian mammalian and human but it’s really just three generations of brain.

One of the most important pieces that’s hidden down here is the thalamus and it’s sort of like the router; pretty much everything goes through it both directions and so it can both excite and inhibit. It’s divided into a whole bunch of sections; each of that sections has different responsibilities and those responsibilities are coordinated but in the end the routing is done here wherever the decision to route comes from.

Most of the feedback loop is processed here and it’s this feedback loop that helps us control our attention or focus. The limbic system – i don’t like calling this emotional or feeling brain because it’s sort of freudian.

Instead i think of it as motivation because when you’re just instinctual you don’t have any choice but once you have a little bit of choice or reason or socio socialization you need to have some motivation. In other words we have to increase the level of sophistication of motivation so i tend to – you’ll see this later – like some authors combine the limbic area with the prefrontal cortex which is where we do our real reasoning.

We’re going to come back to the limbic system later because while the brainstem sits atop the spinal cord, the thalamus sits atop the brainstem, the limbic system again sits atop the thalamus, and the neocortex sits atop the limbic system.

The information flow is from the brainstem and thalamus into the neocortex and then back down into the limbic system.

So let’s return to the brainstem and thalamus and follow the flow of information.

The top of course is the neocortex which is where we do our thinking. From there we go into the white matter and there’s three sets of neural fibers – these are myelinated again like the rest of the nervous system which makes them white.

There are projection fibers, those are things that enter and leave which is pretty obvious – up and down – so you have up and down fibers projection.

You have association fibers which connect the front and back because your brain is divided into hemispheres especially quadrants but we’ll do it in hemispheres.

And commensal fibers which connect the two hemispheres to each other and so this is a quick look at some of the groups of fibers. I felt this one at least got the idea across but i like this one more; this shows just how connected everything is.

One of the themes that we want to get across is if it can be connected in your brain it is somehow. Now in some cases there are these very long fibers and in other cases there are cascades of fibers but information to be communicated at electrical levels, chemical level, physical level, harmonic level – in other words uh things can be communicated together in impulses or periods – they will be communicated.

It is amazing how much connectivity is here and how efficiently evolution made use of a very very expensive organ.

If i haven’t said it before the brain is per gram about 11 times as costly as a muscle.

This is a wonderful cutaway you see this one everywhere i think every textbook has it of the corpus callosum.

This shows the commissary fibers that connect the two sides of the hemisphere. This has been cut away as a v shape from the top so you can see it and here is an example from the side to side and you can see the center how these are connected.

The cortex is divided into that white matter which we just saw those myelinated connections but when we get to the very outer layer it’s not myelinated.

This they call it the gray matter which is the stuff that’s not myelinated and the white matter which is.

And so i think it’s better to look at it as the white matter is wiring and the gray matter is computing so to speak.

This diagram does a fairly good job of showing how many folds there are and how those folds solve the problem of surface area while keeping our heads large enough to exit a poor woman’s vagina during birth.

And so one of the solutions nature has had saves volume improves communication and reaction speed and limits the cost is to use all these folds. Now all those folds have purposes; they are broken into areas.

At the bottom of the back is your balance and coordination of the cerebellum. Hearing and as in your temporal lobe along the side – many other things; vision is toward the back.

The association between vision and the body is in the top rear and then you can look at the bottom left hand corner – you’ll see that the sensory and the motor areas are fairly sharply divided.

And that the sensory areas along the top as you can see if you look at the diagram from the top and down as leg trunk arm face goes down to tongue and larynx below that.

These sections are right next to each other so the sense and the action – input output – are right next to each other. And then the front is the planning area and so you work from senses in the back toward continuous abstraction on the front with the frontal lobe continuing from primary motor to pre-motor to eye field or motion tracking, working memory for spatial tasks, and then into task management working memory tasks and solving complex multi-task problems. S

o from bottom or back to top and front we continuously assemble ambiguous seemingly unrelated information into whatever it is we choose to concentrate upon.

Well if we choose to concentrate at all.

So what we’re going to explore is how we process information in that sequence.

Here’s the homunculus – the primary reason i wanted to show you is say that these nerves aren’t evenly distributed. I love this example because if you look at the leg trunk arm hand face it’s that little strip and you can see how the different nerves are arranged along the edge of the brain and that they map pretty much your physical structure.

We have a lot of nerves devoted to our hands and our lips and our tongue; this is why we have such facility with our fingers it’s quite expensive that if you watch the great apes – gorillas or chimpanzees – you notice how they use their thumb and their forefinger together to pinch things.

They don’t have the manual dexterity we do. Primary audio area is here; Wernicke’s area process that information. It then sends the information over to Broca’s area which is where speech is organized and then put into the motor area at the bottom.

That bottom part of the motor region is where the larynx is.

Now speech is not vocalization dependent; we can communicate through gesture through drawing through speech or singing through bodily motion so it’s not verbally dependent.

My point being only that the communication facility is not limited to the production of words.

o the scope of this unit is an overview of the nervous system. Talk about the flow of information through it. We’re going to cover some of the anatomy; we’re going to cover only that anatomy necessary for describing this narrative we’re putting together. We’ll talk about the functions of those components in the nervous system but in particular, the functions of neurons, the columns, the hypothalamus. And I’m going to talk about how great we create maps of reality with those underlying functions and then a general explanation of how we make choices and produce memories. And at the end hopefully we’ll have the narrative or theory of how the brain and mind produce experience action and memory; this is part one, the anatomy.

The nervous system which we cover input, integration, calculation, memory and output. Well we’re going to start out with a nervous system overview which something most of us probably know about; the central nervous system consists of the brain and the spinal cord. The peripheral nervous system is everything attached to that and it’s divided into two sections: the sensory or input, they call it afferent division; and the motor or efferent division or the output division. The motor neuron system is divided into a couple of pieces: the autonomic nervous system which controls things like your heartbeat and your glands; the sympathetic division which gets you ready for fight or flight which is the excitatory division; the parasympathetic division which is, does the opposite which calms you down and puts you at rest; and then lastly we have the somatic nervous system or the motor neurons which is the voluntary system.

The structure of the nervous system no matter where in it is approximately the same; it’s uh basically this neural tissue cells along the line function sort of like christmas light repeaters and uh there’s quite a bit of myelination on the outside which is an insulator which insulates them from damage but also prohibits degradation of the signal. As a simple overview of the evolution of the brain there we see the at the bottom the embryo at one month at five weeks and then the child. And as you can see we sort of looked like a fish at the beginning; you know a very primitive uh lizard in the middle; and we need to finally develop into the the mammal and the human at the end there. We can see in the lower right hand corner the nervous system of a fish; forgive me if i can’t recall which one it is but you can see the spinal cord, you can see the cerebellum which is this little lump there and that cerebellum is what precalculates all of your physical motion. A bit of the optic region where your vision is processed, the thalamus which regulates input, the purple area at the beginning is the cerebrum where what little thinking a fish does is processed, and the olfactory bulb which is kind of interesting because in all of us it’s the information that isn’t pre-processed.

Now pretty much everything else is pre-processed before it gets to us except sent but if you look at the left we have the cerebrum which is the large overlying layer which we’re going to talk mostly about, the cerebellum which i covered already, then the parts of the reptilian brain which regulate your body involuntarily, these regulatory or pre-processing functions are the medulla which connects the brain to the spinal cord and manages traffic between the cerebellum and the sabri cerebrum and manages some traffic between the cerebrum and cerebellum and it acts as the sort of control center for the autonomic functions specifically of the heart and lungs. And it regulates your digestion, breathing, you know things like sneezing, swallowing or even that wonderful thing we call vomiting.

The pons is next and it is a sort of preprocessor for the senses, particularly for the head; it’s the largest part of the brain stem. It’s a group of nerves that connect different parts of the brain together and they serve as a bridge between various parts of the nervous system including the cerebellum and cerebrum. The pons also relay signals from the forebrain to the cerebellum and this helps organize involuntary actions like posture and equilibrium as well as some others that like respiration sleep bladder control, hearing tastes and eye movement. A lot of your facial expressions and even the possibility of dreaming there’s an awful lot that goes on there that regulates what goes on in the head.

The midbrain helps control eye movement and processes visual and auditory information. We’re going to see that vision is extremely complex and is spread across multiple areas of the brain – not only this area here but also the back of the brain, the visual cortex, the visual association area, and even eye movement that allows tracking is done on the very front of the brain. Over on the upper right you can see that with this reptilian brain is purely instinctual, it’s things that prevent us from hurting ourselves because we have choice. And people will call these the reptilian mammalian and human but it’s really just three or three generations of brain.

One of the most important pieces that’s hidden down here is the thalamus and it’s sort of like the router; pretty much everything goes through it both directions and so it can both excite and inhibit. It’s divided into a whole bunch of sections; each of that sections has different responsibilities and those responsibilities are coordinated but in the end the routing is done here wherever the decision to route comes from. Most of the feedback loop is processed here and it’s this feedback loop that helps us control our attention or focus. The limbic system – i don’t like this emotional or feeling brain because it’s sort of freudian. Instead i think of it as motivation because when you’re just instinctual you don’t have any choice but once you have a little bit of choice or reason or socio socialization you need to have some motivation. In other words we have to increase the level of sophistication of motivation so i tend to – you’ll see this later – like some authors combine the limbic area with the prefrontal cortex which is where we do our real reasoning. We’re going to come back to the limbic system later because while the brainstem sits atop the spinal cord, the thalamus sits atop the brainstem, the limbic system again sits atop the thalamus, and the neocortex sits atop the limbic system. The information flow is from the brainstem and thalamus into the neocortex and then back down into the limbic system. So let’s return to the brainstem and thalamus and follow the flow of information.

The top of course is the neocortex which is where we do our thinking. From there we go into the white matter and there’s three sets of neural fibers – these are myelinated again like the rest of the nervous system which makes them white. There are projection fibers, those are things that enter and leave which is pretty obvious – up and down – so you have up and down fibers projection. You have association fibers which connect the front and back because your brain is divided into hemispheres especially quadrants but we’ll do it in hemispheres. And commensal fibers which connect the two hemispheres to each other and so this is a quick look at some of the groups of fibers. I felt this one at least got the idea across but i like this one more; this shows just how connected everything is. One of the themes that we want to get across is if it can be connected in your brain it is somehow. Now in some cases there are these very long fibers and in other cases there are cascades of fibers but information to be communicated at electrical levels, chemical level, physical level, harmonic level – in other words uh things can be communicated together in impulses or periods – they will be communicated. It is amazing how much connectivity is here and how efficiently evolution made use of a very very expensive organ. If i haven’t said it before the brain is per gram about 11 times as costly as a muscle.

This is a wonderful cutaway you see this one everywhere i think every textbook has it of the corpus callosum. This shows the commissary fibers that connect the two sides of the hemisphere. This has been cut away as a v shape from the top so you can see it and here is an example from the side to side and you can see the center how these are connected. The cortex is divided into that white matter which we just saw those myelinated connections but when we get to the very outer layer it’s not myelinated. This uh and they call it the gray matter which is the stuff that’s not myelinated and the white matter uh which is. And so i think it’s better to look at it as the white matter is wiring and the gray matter is computing so to speak.

This diagram does a fairly good job of showing how many folds there are and how those folds solve the problem of surface area while keeping our heads large enough to exit a poor woman’s vagina during birth. And so one of the solutions nature has had saves volume improves communication and reaction speed and limits the cost is to use all these folds. Now all those folds have purposes; they are broken into areas. At the bottom of the back is your balance and coordination of the cerebellum. Hearing and as in your temporal lobe along the side – many other things; vision is toward the back. The association between vision and the body is in the top rear and then you can look at the bottom left hand corner – you’ll see that the sensory and the motor areas are fairly sharply divided. And that the sensory areas along the top as you can see if you look at the diagram from the top and down as leg trunk arm face goes down to tongue and larynx below that. These sections are right next to each other so the sense and the action – input output – are right next to each other. And then the front is the planning area and so you work from senses in the back toward continuous abstraction on the front with the frontal lobe continuing from primary motor to pre-motor to eye field or motion tracking, working memory for spatial tasks, and then into task management working memory tasks and solving complex multi-task problems. So from bottom or back to top and front we continuously assemble ambiguous seemingly unrelated information into whatever it is we choose to concentrate upon.

Well if we choose to concentrate at all. So what we’re going to explore is how we process information in that sequence. Here’s the homunculus – the primary reason i wanted to show you is say that these nerves aren’t evenly distributed. I love this example because if you look at the leg trunk arm hand face it’s that little strip and you can see how the different nerves are arranged along the edge of the brain and that they map pretty much your physical structure. We have a lot of nerves devoted to our hands and our lips and our tongue; this is why we have such facility with our fingers it’s quite expensive that if you watch the great apes – gorillas or chimpanzees – you notice how they use their thumb and their forefinger together to pinch things. They don’t have the manual dexterity we do. Primary audio area is here; Wernicke’s area process that information. It then sends the information over to Broca’s area which is where speech is organized and then put into the motor area at the bottom. That bottom part of the motor region is where the larynx is. Now speech is not a vocalization dependent; we can communicate through gesture through drawing through speech or singing through bodily motion so it’s not verbally dependent. My point being only that the communication facility is not limited to the production of words. We have 16.3 billion neurons.

1. Neocortex: The neocortex, a part of the cerebral cortex, is estimated to contain around 16 to 20 billion neurons. The neocortex is involved in higher-order brain functions such as sensory perception, cognition, generation of motor commands, spatial reasoning, and language.

2. Entire Brain (including the Cerebellum): The entire human brain is estimated to contain about 86 billion neurons. Of these, a significant portion – around 69 to 70 billion – are found in the cerebellum, a region of the brain that plays an important role in motor control. The cerebellum’s neurons are more densely packed than those in other brain areas, which accounts for its high neuron count despite its smaller size compared to the neocortex.

If you look at the size of our cerebellum it’s not all that big but if you look at the cerebellum on the elephant which has got a very big body to move around it’s quite a bit larger but that elephant only has 5.5 billion neurons. It’s a lot bigger but it has only a third of the neurons even a western gorilla has just a little more than half. So brain size varies a great deal and it really does matter not only the size but how many neurons you have in there. Well that’s the end of section one of this lesson. In this section we’ve covered the major components of the nervous system: the sensory, central and motor nervous systems; the three generational structures of the brain and a quick bit on the thalamus’s router; and the general composition of the cerebrum including its divisions, functional areas and its inner white matter and outer gray matter. In the next section we’re going to explore the neocortex at the next level of resolution.

If you look at the size of our cerebellum it’s not all that big.

.But if you look at the cerebellum on the elephant which has got a very big body to move around it’s quite a bit larger but that elephant only has 5.5 billion neurons. It’s a lot bigger but it has only a third of the neurons even a western gorilla has just a little more than half.

So brain size varies a great deal and it really does matter not only the size but how many neurons you have in there.

Well that’s the end of section one of this lesson. In this section we’ve covered the major components of the nervous system: the sensory, central and motor nervous systems; the three generational structures of the brain and a quick bit on the thalamus’s router; and the general composition of the cerebrum including its divisions, functional areas and its inner white matter and outer gray matter. In the next section we’re going to explore the neocortex at the next level of resolution.

– Generated with https://kome.ai