Some Behavioral Peculiarities of Nervous System Formed by Evolution
Published by zeroca
05-30-2005
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The thread – “how to maximize the number of neuron connection?” in the section – “cognitive neuroscience” prompted me to write this article to clarify with popular language some qualitative processes conducted in nervous system, i.e. to show that explanations of processes, happening in living organism not always can be grounded on quantitative analysis:
Nervous system can be divided into two parts: central and peripheral. The central part bears the function of analyzer, but peripheral part – the function of receiving and conducting internal or external irritation. By function itself the nervous system can be divided into 1. motor system and 2. sensitive systems. (We must single out particularly a vegetative nervous system, but more about that later). The first has functions connected with volitional actions: for instance: flexion, straightening, rotation, elevation are the functions of motor nervous system. From the functions of sensitive nervous system we can note sense of touching, of cold and warm, of vision, of tasting, of hearing, of smelling… Motor nervous system is centrifugal, i.e. conducts motor impulses from the cerebral cortex to the periphery (to make active/passive particular muscle or group of them).
Sensitive nervous system is centripetal, i.e. conducts sensitive impulses from the periphery to cerebral cortex.
But right now I’d like to attract your attention to vegetative nervous system and its correlation in the organism: Vegetative or local nervous system consists of two pairs of nerves: sympathetic and parasympathetic. Anatomically central parts of sympathetic nervous system (Symphaticus) and parasympathetic nervous system (mainly Vagus, which is one from the 12 cranial pairs (X)), i.e. their nuclei are situated in several places of nervous system.
The essential, that we can say about these two nerves from anatomical point of view is that they branch out inside the organism and unlike of motor and sensitive nervous systems (the latters have 1.their own zones in a cerebral cortex, 2.conductive system and 3.particular, special place of starting or termination in a periphery) the formers reach all internal organs, glands of secretion, all muscles and vessels, i.e. fall into tiny, superfine branches (i.e. have many places of termination). At the same time whiles motor nervous system conditions volitional actions, the vegetative nervous system (the truth – under the control of the cerebral cortex) conditions non-volitional processes (such as starting of intestinal peristalsis or its blocking, dilatation or constriction of vessels, rising or lowering of heart’s pulsation, dilatation or constriction of alveoli of lungs etc…)
The essential as well, what we can say about these two nerves (sympathetic and parasympathetic, i.e. Symphaticus and Vagus) is that they are antagonists of each other and within the limits of any particular internal organ act as opposites of each-other (for instance: the increasing of activity of Vagus results in lowering of heart’s pulsation, but increasing of activity of Symphaticus - in increasing of it). To say briefly Symphaticus figuratively is called the nerve of activity or the day’s nerve, but Vagus – as the nerve of passivity, or the nerve of night. Below is shown the scheme of behavior of each of them: "Answers of working organs during stimulation symphatetic and parasimphatetic nerves" (Haulica, J., 1978)
The most important I’d like to emphasize, is the mechanism of forming of these two systems and its analysis regarding to the process of evolution: Until indicating the practical example, I’d like to touch briefly such functions of cerebral cortex as are functions of irritation-inhibition, and phenomenon of dominant: All (motor or sensitive) parts of nervous system have their prevailing zones in a cerebral cortex: for instance, in a human’s organism central part in cortex for lower extremities occupies a zone of parietal lobe – so called pre-central convolution (gyrus), but for the eyesight – the large as well zone in occipital lobe.
Each sphere of nervous system has as well associative, convergative connections to other parts of cortex, i.e. the parts, which doesn't’t present a prevalent specific zone for mentioned sphere. For instance the sphere of reproduction is characterized by richest associative connections with almost every other motor and sensitive nervous system zones in the cortex.
The phenomenon of dominant consists in following:
Under the influence of some (any complex, any single) external or internal stimulants on the organism the irritation of corresponding zone of cerebral cortex automatically results in simultaneous inhibition of other needless cerebral zones, even sometimes the generalized inhibition spreads over almost thorough cortex (except for irritated zone of it). For instance, in a moment of syngenesis, sexual function and connected with it supplementary associative functions become active, leading process with synchronous spreading of inhibition over functions (needless for this period) of nutrition and self-preservation.
Let’s consider simple particular example taken from wild nature: a deer escaping from tiger, i.e. example of pair: predator-prey in a period of chasing (because the chasing can be the best example of crucial moment) and their nervous systems’ activities (specifically of vegetative nervous system‘s) during and after ending of chasing period.
During the period of chasing the extremities carry out the prevalent, leading function (lower extremities - in case of human) i.e. dominant in this particular case becomes the central part, respective to extremities (part of cortex) with synchronous inhibition spreading over all other “needless” zones: I.e. to say briefly both animals are concentrated on developing of highest possible acceleration within the period of chasing.
I think that very interesting is behavior of vegetative nervous system: i.e. correlation between sympathetic and parasympathetic systems as antagonistic systems: During the period of chasing in both organisms happens “turning on” of Symphaticus: - Pulsation increases, i.e. the quantity of beating of pulse for a minute increases.
- The quantity of systole volume (the volume of blood, pumped over to Aorta, i.e. to circulatory system with one compression of heart) increases.
- coronary arteries (i.e. arteries of heart) dilate, as muscles of loaded heart need more supply with blood.
(The bloody stream to muscles of heart increases). - Blood-vessels of extremities dilate. (The bloody stream to extremities increases).
- Lung’s alveoli dilate as well, i.e. supply with oxygen increases (oxidation increases).
- Metabolic processes increase.
- Intestinal peristalses experiences blocking, i.e. gastrointestinal tract is in “hung-up” condition, but sphincters (pyloric, anal...) are tensed.
- Urinary bladder’s detrusor is relaxed, sphincter - tensed.
- Blood-vessels of brain are constricted, blood supply to brain decreases…
- Glycogenolysis increases because the glucose is needed as energetic source…
(For people who don’t know, the detrusor and sphincter are antagonist muscles of urinary bladder, when sphincter is relaxed, the detrusor is active (urination) and vice-versa (inhibition of urination), and I’d like to emphasize as well that successive activation-blocking of the system detrusor-sphincter of urinary bladder may happen anytime but mainly the sphincter is constricted ( i.e. it’s active) in the period of chasing, but after it becomes passive (precisely opposite of detrusor’s activation-blocking processes)).
And it happens on every “level” of organism: the organ that’s needless is passive, but all rest organs – active… and choosing of internal organs’ active and passive conditions during a crucial moment and after it within the whole organism happens by vegetative nervous system’s automated functioning (formed throughout the period of evolution) …
And very interesting is “conduct” of uterus in the period of chasing: pregnant uterus is in constricted condition (to carry a fetus), non-pregnant - is in relaxed condition (because of absence of carrying function), but in both cases determinative is Symphatetic system (Symphaticus)…
After ending of chasing (either deer escapes or tiger catches it) survived organism at once experiences changing of activity of vegetative nervous system in radically opposite direction (i.e. at once happens choosing of most favorable conditions for resting):
Parasympathetic system (Vagus) becomes “turned on”: - Pulsation decreases, i.e. the quantity of beating of pulse for a minute decreases.
- The quantity of systole volume decreases.
- coronary arteries constrict, as muscles of heart need less supply with blood.
(The bloody stream to muscles of heart decreases). - Blood-vessels of extremities constrict. (The bloody stream to extremities decreases).
- Lung’s alveoli constrict as well, i.e. supply with oxygen decreases (oxidation decreases).
- Metabolic processes decrease.
- Intestinal peristalsis experiences activation, i.e. gastrointestinal tract is in “active”, “waving” condition, but sphincters (pyloric, anal...) are relaxed.
- Urinary bladder’s detrusor is active, sphincter - relaxed.
- Blood-vessels of brain are dilated, blood supply to brain increases…
- Glycogenolysis decreases…
I.e. as a conclusion we can say that during the activity of any part of central nervous system there exists a dominant, and activation as well of connected with dominant of associative supplementary systems with simultaneous inhibition of “needless” nervous and somatic systems. Different processes have their different specific dominant in a cerebral cortex and associatively bind with it relatively stable irritational-inhibitional stereotype formed during the process of evolution. |  Latest 5 articles | | |
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I would like to say thanks for such a well researched thread Zeroca,it made
interesting reading,and am amazed at the complexity of it all,and how beautiful
it all is,simple yet complex,and evolved over many aeons of time,tell me can
electrical impulses from the brain override or switch off reflex actions,such as
flight-from -danger,or recoil from touching a hot object?
Look forward to other threads from your good self.
kind regards.michael. | | |
By
zeroca
on
10-11-2005, 08:46 AM
| | Of course, the impulses from brain (from cerebral cortex) can override any kind of reflexes (conditioned or unconditioned ones). As I mentioned in my biography, I don’t work as a physician any more (since 1996), but anyway I’ll prepare a post about reflexes and the role of cerebral cortex in processes of correlation in human’s organism. It will take some time.
Best regards, Merab. | |
Last edited by zeroca : 10-19-2005 at 04:41 AM.
|
By
zeroca
on
10-25-2005, 05:50 AM
| | Training of brain
Quote: |
Originally Posted by mkirkpatrick canelectrical impulses from the brain override or switch off reflex actions,such as
flight-from -danger,or recoil from touching a hot object?
| Reflex is organism’s automated reply to internal or external stimulant. Each reflex consists of two arcs: ascending and descending, and also of intermediate (i.e. central) part. Reflexes are of several types: skin-reflex, tendon-reflex, bony-reflex, etc… Irritation caused by stimulant reaches the central part of nervous system by ascending arc, and impulse, returned from there by descending arc makes active muscles, glands of secretion, or blood vessels… Basically reflexes are divided into two parts: 1.unconditioned and 2.conditioned ones: 1. Unconditioned reflexes are inherited and are formed during the process of evolution. They are stable, i.e. remain relatively permanent during the whole life of organism, but 2.conditioned reflexes – are based on, or rather associated with unconditioned reflexes. Unconditioned reflexes are those of self preservation, of nutrition, of syngenesis … When touching the hot object, the impulse through an ascendant sensitive nerve reaches the CNS (central nervous system), returned from where a motor impulse causes an activation of group of muscles that results in hand’s rising or flexing, i.e. results in taking of affected extremity away from destructive stimulant, so this reflex can be considered as an example of self-preservational types of them. A good example for imagining of conditional reflexes is experiments on dogs, conducted by Russian physiologist Pavlov: Some conditional stimulant, for inst. ringing bell that coincides with the act of nutrition (with unconditional reflex of feeding) during some period repeatedly, turns into the factor causing conditional reflex, i.e. the association of ringing with having a meal results in forming of conditional reflex of ringing, which ends with excretion of gastric juice with bell ringing, even without bringing a meal, i.e. causes readiness for feeding just with bell ringing, but in case of not supporting afterwards the ringing with feeding, the conditional reflex eliminates gradually, i.e. generally, for existence of conditional reflex permanent association with unconditional stimulant is needed. The capability of forming of conditional reflexes is also the result of evolution of brain, especially of cerebral cortex and helps to adaptation of organism to environment, i.e. the mentioned mechanism gives to organism a potential of choosing from many factors the one, which’s in probable relation with conducting of some unconditional function: of nutrition, of self-preservation, or of syngenesis…, that’s to say helps to fulfilling of basic functions of organism. As for me, I think that since the reflex itself is an automated act (an automated reply to irritation), so it belongs to subconscious processes. What’s the difference between conscious and subconscious processes? During the process of evolution, with the purpose to spare the organism’s resources, the ability of automated, subconscious fulfilling of some actions is formed: Good examples are to study car driving or, let’s say, to study typing: For some, relatively long period of time by repeating of conscious actions of switching a gear lever, or searching any key on a keyboard one can obtain automated carrying out of mentioned actions, what afterwards frees the brain from load to concentrate on each composite action (in first case from switching a gear lever, in the second – from finding each key on a keyboard every time) and freed part of consciousness can be engaged with another action. The mechanism of forming of conditional reflexes can be used to automate any sort of actions: e.g. by boxer to form the feint of hit or block, by worker to form some habits of work etc… Even the organism has the capability of forming of complex conditional reflexes, i.e. reflexes with successive, consecutive composite simple actions, or synchronous, simultaneous group of them. The mentioned ability of brain can be used as well to form the function of inhibition of brain (and of the thorough organism in whole) to some irritation, caused by external or internal stimulant, and also to strengthen mentioned function of inhibition. If by using will-power (the function of cerebral cortex) we make to inhibit automatic reply of organism to any kind of external irritant (for instance to stimulant of pain), with many repeat of mentioned inhibition we can form a habitual cortical inhibition, which can be reached easily in result of this kind of “training” little by little. But I’d like to mention here that much easier is to train the brain according to the natural (biological) irritational-inhibitional code of organism, i.e. by taking into account evolutional stereotype of brain during training: Concrete example from my own practice: During the sitting in the pose of lotus (yogic exercise with crossed lower extremities) visceral kind of pain begins in approximately half an hour. During the exercise enduring this pain gradually becomes harder, and ultimately it results in uncrossing of extremities after passing approximately an hour from exercise starting, but in case of beforehand jogtrot for a half an hour the pose of lotus afterwards becomes easier and more comfortable (i.e. one can endure the pain easier). And that’s simple to explain: During the jog-trot the activation of part of cerebral cortex for lower extremities (i.e. of pre-central large and powerful convolution of cortex) results in unconditional inhibition of almost thorough rest cortex (biological code formed by evolution, needed for escape) and after getting of inhibition of cortex (the latter lasts for some period) forming of habitual inhibition of enduring the pain becomes easier - easier is to associate forming of habitual inhibition with ready unconditional inhibition of cortex (i.e. to form the conditional inhibition associated with unconditional inhibition given in reflex of self-preservation – in our concrete case with inhibition, happened during escape). As a conclusion we can say that we can form any kind of conditional reflex, or conditional inhibition of reflex by training, but better is to combine the training with biological code of organism. | |
Last edited by zeroca : 10-18-2006 at 03:10 PM.
| | |  surface of the brain
Quote: |
As a conclusion we can say that we can form any kind of conditional reflex, or conditional inhibition of reflex by training, but better is to combine the training with biological code of organism.
| You are a good analyst of what is happening anyway.
Let us not forget that the cerebral cortex, that 2 millimeter layer of the surface cells of the cerebrum supported by the scaffolding that are the glial cells grew larger and larger in surface area over the evolutionary timeframe to accommodate the ever increasing intelligence of the human being, as this evolutionary process diverged the human further and further away from the animal.
To what do you attribute the cause of this evolutionary trend of the expanding cerebral cortex and the growing intelligence of the human being as opposed to that of the animals, which only became better animals? | |
Last edited by baudrunner : 12-29-2005 at 04:06 PM.
Reason: content
| | | | Stem cells offer the best chance at finding the mechanism of evolution. They can become any cell. Somehow, they did this in increasing numbers, possibly due to greater demand of the brain for more processing of increasing amounts of information. Perhaps we found a way to give ourselves more categories. | | | | | evolution on the fly...
Hi, Michelle
More "categories" were probably provided by the DNA's "Simpson's Desert Regions", which were once thought to have no useful function and were once commonly referred to as "junk DNA". This "junk DNA" represents about 98% of the entire DNA molecule. Researchers have now identified certain segments of these regions which facilitate the process in gene selection for protein synthesis and appear to provide some other useful functions after all, in contrast to the task of providing the actual gene template, which is the job of the allele, or genetically coded portion.
It is my opinion that during evolution of the eukaryote, or nucleated cell, the newly evolved DNA molecule stored information pertaining to past successes in protein synthesis in these long DNA portions, providing it with a memory of sorts, and that they continue to provide an important data base of information which is used during gene selection and generation of the RNA. This DNA portion then serves up the gene which acts to provide the protein template and thus is a learning program which might act to maintain the integrity of the genetic code and might even enhance the gene periodically thereby.
Stem cells, while seemingly magical and highly evolved, are actually "primitive" cells. It is possible that they might very well provide us with more insight into the nature of evolution by studying the actual mechanism that determines which cell type it will become. The kind of inter-cellular communication required is somewhat different from the inter-molecular communication mechanisms which guide RNA production. At some point, however, the information needs to be stored, and that would be the right stage to pinpoint evolution in progress. | |
Last edited by baudrunner : 12-30-2005 at 06:12 PM.
Reason: content
| | |
I mean this in the most flattering way, but you sir, are an iatrophysicist. Your knowledge of the human condition and physics makes you uniquely qualified to comment. Your posts would make a good textbook, and I suggest you are ready for publishing. I have never said that about anyone in my entire life.
Do you believe the universe can experience pathology? I await your reply.
Also, I discovered something in Russel's Paradox. If you have a universe which doesn't contain a universe, you have what existed before the Big Bang. Following this, does the universe of all universes that do not contain universes contain a universe? I answered yes. Your thoughts would be as always, nice to hear.
Oh yeah, I'm reading Quantum Mechanics Demystified now. I promise not to quote even so much as an equation. How's that for progress. She can be taught! | | | | | | Perhaps there is no such thing as junk DNA, but perhaps sequences go down for awhile. Wouldn't that be an interesting development? | | | | |  Sorry zeroca, and incidently,
There is no doubt much more to the nature of human evolution by progressive enhancement of the DNA than we can know at present, it is simply too complex. But my thinking is that there are multiple functionalities which work in tandem. For example, I developed a theory whereby the 98% of DNA not encoded for protein synthesis is also purposeful in other ways. The assembly of the DNA molecule inside the nucleus is bundled into a complex knot of sorts, winding and bending and folding around and around. In the same way that a bend in a steel bar exposes the curved corner to a greater possibility of fracture, note the spreading texture on the surface, and where repeated bending back and forth can actually break it, the corners and bends of the DNA molecule are also potentially more vulnerable to mutations because of their weakend bonds, which are stretched. If 98% of the DNA are essentially expendable segments not crucial to the continued existence of the host then statistically they present a reduced probability that a mutation will occur on a valid gene segment. I think that the actual characteristic conformation of the DNA is unique to the individual and that the basic form is passed on to offspring, hence inherited genetic diseases, which over time will stop expressing themselves as the DNA evolves.
I would like to apologize to zeroca for sort of hijacking this thread, or at least deviating from its intent, which started originally as a discussion of the nervous response mechanism and somehow veered into a discussion of the process of evolution. Sorry about that, no doubt your post will be a popular reference for future studies by all of us. Thank you. | | | |
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