Neurons, DNA, Memory and Learning

[icakeov]

Hello

I am not an expert in this field but I am really hoping to understand as much as I can about the concepts described in my questions below. I might be using some improper jargon and expressions, so I apologize if some things are incorrect or confusing.

#1 Do all the neurons have the same expression of the DNA that they contain? (DNA is the same in all of them, right?) Do the neurons cells get instinct behaviors directly from the DNA that they contain?

#2 I suppose the behaviors that are learned (rather than instinctive) come from environmental stimulus and are expressed in combination with the pre-programmed genetic instinct. Also, I imagine that the learned behavior needs to happen a bunch of times through a given batch of nerve cells in order for the behavior to be remembered by the nerve cells' pathway that is being created. Is there a certain amount of times before this pathway becomes permanent? Does the pathway always stay more or less the same (since the same nerve cells would need to be stimulated, right?)? And is there a limit to how many different "stimuli"/"pieces of information" a give nerve cell can "transmit"/"hold" (I read somewhere it can be anywhere from 1000 to 10,000!)?

#3 Once a nerve cell "adopts" a learned behavior, and it becomes "permanent", can it ever "forget"/"discharge" it? Or does the "charge"/"information" stay in that nerve cell for the rest of the person's life? Or does it slowly "fade" until it totally perhaps eventually dissipates?

#4 I read somewhere that a new "batch" of nerve cells need to override an old, habituated, unwanted behavior, which actually never really "goes away", and merely stay "overridden", and can in fact return back if the new habituated behavior doesn't "hold-up". Is this true? And if it is, is this new "information" "stored" within the same batch of neurons, along the same pathway that held the "old" memory or is this a whole new batch of neurons, with a totally new pathway, with the "new" information somehow "overriding" the other neurons that hold/transmit the "old" behavior? (or both?)

Many many thanks!

 

[Dr. Courtney]

Every cell in the body has the same dna.

 

[Ygggdrasil]

#1 Do all the neurons have the same expression of the DNA that they contain? (DNA is the same in all of them, right?)

Every cell in the body has the same dna.

While all cells in the body contain largely the same DNA, if certain mutations happen during development (i.e. after the initial cell division when the embryo splits into the two cell stage), then these mutations will only occur in a subset of the cells in the body. Such mutations cause a phenomenon called mosaicism. Interestingly, mosaicism within the brain caused by the insertion of retrotransposon sequences within the DNA of neurons has been postulated as a http://www.nature.com/nrn/journal/v15/n8/full/nrn3730.html.

As for the general questions about learned vs instinctual behaviors, here's an old PF thread that you might find interesting: https://www.physicsforums.com/threads/instinct-encoded-in-dna.602902/

 

[icakeov]

Thanks for your response Ygggdrasil,
I didn't realize that DNA can mutate within the body in its lifetime. And that it happens in neuron cells. Is this something that happens as a rule of thumb or more of a rare occurrence with neurons?
Thanks for the link to the old PF thread, that thread is in fact how I stumbled upon this website when I googled about this topic. It didn't quite answer the questions that I had so I thought I'd post a new one here.

 

[DiracPool]

#1 Do all the neurons have the same expression of the DNA that they contain? (DNA is the same in all of them, right?)

All neurons contain the same DNA, but the "expression" of that DNA depends on what type of nerve cell is being produced. Obviously different genes are expressed depending on whether you're a mitral cell, amacrine cell, pyramidal cell, or a GABA-ergic inhibitiory interneuron.

Do the neurons cells get instinct behaviors directly from the DNA that they contain?

That's an oversimplistic concept of the way neurons and neuron networks work. The short answer is no.

is there a limit to how many different "stimuli"/"pieces of information" a give nerve cell can "transmit"/"hold" (I read somewhere it can be anywhere from 1000 to 10,000!)?

I think neurons in vitro can be artificially stimulated to up to 1000 pulses per second; there is a refractory period that places a limit there. However, these extreme frequencies are almost never seen in in vivo populations of neurons. The typical neuron in the mammalian brain pulses at less than 10 per second, it's the collective activity of 100's of millions of neurons all pulsing at about 3-4 spikes per second that drive brain dynamics and learning.

#3 Once a nerve cell "adopts" a learned behavior, and it becomes "permanent", can it ever "forget"/"discharge" it? Or does the "charge"/"information" stay in that nerve cell for the rest of the person's life? Or does it slowly "fade" until it totally perhaps eventually dissipates?

Nothing is "permanent" in brain dynamics. And you're looking at it in the wrong way, something like an atomistic perspective of brain function. Learned behaviors are the the product of modified "Hebbian cell-assemblies;" they are not a product of the biology and genetics of single neurons. Rewarded behaviors strengthen the synaptic connections between neurons which facilitate the future expression of those behaviors, and unrewarded behaviors lead to the extinction of those behaviors through atrophy of those connections.

is this new "information" "stored" within the same batch of neurons, along the same pathway that held the "old" memory

Yes

or is this a whole new batch of neurons, with a totally new pathway, with the "new" information somehow "overriding" the other neurons that hold/transmit the "old" behavior?

No

The brain doesn't work like a computer, there are no separate sectors and hard drives to store separate information. Everything is stored, superimposed, on the same medium. Everything is constantly being written and overwritten, so practically, no, no memory is ever completely lost, but it can be so weakened that it is effectively lost, and given the right conditions an effectively lost memory can be regained or "reignited," so to speak.

 

[atyy]

Thanks for your response Ygggdrasil,
I didn't realize that DNA can mutate within the body in its lifetime. And that it happens in neuron cells. Is this something that happens as a rule of thumb or more of a rare occurrence with neurons?
Thanks for the link to the old PF thread, that thread is in fact how I stumbled upon this website when I googled about this topic. It didn't quite answer the questions that I had so I thought I'd post a new one here.

Neurons might have different DNA, but if one wants a very solidly established case, one can look at VDJ recombination.

 

[atyy]

#2 I suppose the behaviors that are learned (rather than instinctive) come from environmental stimulus and are expressed in combination with the pre-programmed genetic instinct. Also, I imagine that the learned behavior needs to happen a bunch of times through a given batch of nerve cells in order for the behavior to be remembered by the nerve cells' pathway that is being created. Is there a certain amount of times before this pathway becomes permanent? Does the pathway always stay more or less the same (since the same nerve cells would need to be stimulated, right?)? And is there a limit to how many different "stimuli"/"pieces of information" a give nerve cell can "transmit"/"hold" (I read somewhere it can be anywhere from 1000 to 10,000!)?

It depends on what you mean by permanent. There are almost certainly no organisms that are immortal, because of the accelerated expansion of the universe http://arxiv.org/abs/hep-th/0106109 :P

More seriously, let's say you define some idea of "permanent". Then there are clearly behaviours or memories that can be learned in one shot, while others need many repetitions.

Here is an example of learning from one time: http://www.ncbi.nlm.nih.gov/pubmed/11572949 (free link to article at the top right).

#3 Once a nerve cell "adopts" a learned behavior, and it becomes "permanent", can it ever "forget"/"discharge" it? Or does the "charge"/"information" stay in that nerve cell for the rest of the person's life? Or does it slowly "fade" until it totally perhaps eventually dissipates?

In a dish and in theory yes, so this probably happens, but off the top of my head, I don't know a solid demonstration that this is true for a behaviour in an animal. http://thebrain.mcgill.ca/flash/i/i_07/i_07_m/i_07_m_oub/i_07_m_oub.html

#4 I read somewhere that a new "batch" of nerve cells need to override an old, habituated, unwanted behavior, which actually never really "goes away", and merely stay "overridden", and can in fact return back if the new habituated behavior doesn't "hold-up". Is this true? And if it is, is this new "information" "stored" within the same batch of neurons, along the same pathway that held the "old" memory or is this a whole new batch of neurons, with a totally new pathway, with the "new" information somehow "overriding" the other neurons that hold/transmit the "old" behavior? (or both?)

Yes, this can happen, eg. in the experiment of Packard and McGaugh: http://www.ncbi.nlm.nih.gov/pubmed/8673408.

They trained rats to do something. After 8 days the animal did it using method A. After 16 days the animals did it using method B. Was it because method B had erased method A, or was method A still there and method B was preferred? Packard and McGaugh silenced a part of the brain. The silencing made the rats revert to method A, indicating that method A was still stored in the brain.

 

[Ygggdrasil]

I didn't realize that DNA can mutate within the body in its lifetime. And that it happens in neuron cells. Is this something that happens as a rule of thumb or more of a rare occurrence with neurons?

It seems like retrotransposon elements may be more active in the brain than in other tissues. Scientists are still working out the best techniques to detect these retrotransposition events, so there are widely varying estimates as to how common these events are in neurons.

In any event, even cells with identical DNA can have different patterns of gene expression. These are though to be due to differences in the way the genes are packaged. Cells can mark specific regions of the genome with certain chemical tags on the DNA or on the proteins that package the DNA which can tell the cell to turn the genes on or turn the genes off. These epigenetic changes probably underlie most of the differences in gene expression between different individual neurons.

Neurons can also have different levels of gene expression in different parts of the neuron. Neurons traffic mRNAs and ribosomes to their various axons and dendrites, and local neuronal activity at specific synaptic spines or terminals may change which genes are made at that synapse and only that synapse. So gene expression can not only vary from cell-to-cell, but in neurons at least, gene expression can also vary within different regions of the cell.

 

[gravenewworld]

You should look up the theory of allosteric modulators...which is absolutely fascinating in my opinion. Allosteric modulators, in theory, have a built in cap for the limit of the their activity, which is quite different than agonists or antagonists (the more you give, the more response you usually see). One idea that people have is that if you could develop allosteric modulators for targeting various things in the brain, you could give massive doses of a drug and have a built in safety mechanism for toxicity, but the real power of allosterism is the fact that you might be able to obtain a uniform response from all neurons. That's something you can not achieve with our current regimen of drugs that target the brain, and it could address how you treat brain diseases when each neuron might be behaving differently due the uniqueness of cell physiology profiles at any given moment in time (some neurons might die at a high dose of a drug that is needed to treat diseased neurons, but if you had an allosteric modulator, you could cap the max response and achieve a uniform treatment amongst all cells).

 

[icakeov]

Thanks so much for your response DiracPool, it clarified so many things!

... the collective activity of 100's of millions of neurons all pulsing at about 3-4 spikes per second that drive brain dynamics and learning.

- And what about different types of information that they can process? Is there a limit to the variety of tasks it can process collectively?

... and unrewarded behaviors lead to the extinction of those behaviors through atrophy of those connections.

- I am guessing that atrophy here means that connections really never "die" but just get weakened or unused (until they might get stimulated again sometime in the future as you pointed out in an answer further in the thread)

 

[icakeov]

Thanks atyy!
Great point about learning happening quick or slowly depending on the circumstances.
Also, your http://thebrain.mcgill.ca/ link had another "procedural memory" reference to different types of learnings were defined, very helpful!
And thanks for the Packard and McGaugh, exactly an answer I was looking for!

 

[atyy]

Also, your http://thebrain.mcgill.ca/ link had another "procedural memory" reference to different types of learnings were defined, very helpful!

That's one of the most celebrated and important discoveries about memory - made by Brenda Milner's observations on H.M. The other major discovery she made with Scofield, the surgeon, is that the medial temporal lobe stores long-term memory, but not the super-long-term memory. See 10:05 for the discovery of procedural memory.



What Brenda Milner looks like in real life.

And thanks for the Packard and McGaugh, exactly an answer I was looking for!

Another related phenomenon is http://www.ncbi.nlm.nih.gov/pubmed/12464700.

I should mention this very interesting paper about the concepts involved in extinction as new learning versus unlearning: http://www.ncbi.nlm.nih.gov/pubmed/15466310.

 

[icakeov]

These are incredible resources! Answered so much! Thanks again atyy!

 

[icakeov]

I am still curious about the relationship between innate and learning behaviors and the influence of DNA on our behavior. I have found this article below and I especially like the image by the end that displays the percentual relationship between innate and learned behaviors in different animals. I was wondering if this is an accurate explanation of how the two different types of learnings develop.
http://www.cals.ncsu.edu/course/ent425/tutorial/Behavior/

 

[atyy]

I am still curious about the relationship between innate and learning behaviors and the influence of DNA on our behavior. I have found this article below and I especially like the image by the end that displays the percentual relationship between innate and learned behaviors in different animals. I was wondering if this is an accurate explanation of how the two different types of learnings develop.
http://www.cals.ncsu.edu/course/ent425/tutorial/Behavior/

I wouldn't take the percentages too seriously. Nonetheless, there are behaviours that are more "innate" and others that are more "learnt". But what is learning? There is no universal agreement, but a simple one is a change in behaviour as a result of experience.

This definition is very broad, and if one thinks about it, it makes development and learning a continuum. http://bioteaching.com/phenotypic-plasticity-2/

 

[icakeov]

Here are some of understandings that I've gained so far (I must admit I was slightly struggling with understanding the explanations of memory extension and spontaneous recovery paper(s)):

- When a brain learns a fear response to a stimulus, the new stimulus that is not fear induced is a new memory. I get that. Does the experiment show that both behaviors can continue to exist independently, depending on wether they are stimulated or not? So at times when the stimulus is fear induced, the original memory will be reinforced, and similarly if the stimulus is not fear induced, the other "stored" memory will be induced?
It seems like any memory will become habituated as long as there is a stimulus to reinforce it enough times, and once it is habituated, then the behavior can propagate, as long as it is not stopped by another behavior? And if the reinforcement stops (or some other behavior overrides it), the habituated behavior will slowly start to "fade".

Furthermore, I understand that neurons (and groups of neurons) can have a certain amount pulses per second, but I am still unclear about whether a certain neural path can "hold" more than one learning? The way I get it so far is that learning can build on top of each other, using one learning to learn more. For example, if I meet someone who has a name similar to a famous actor, I will associate that person to all the movies that I saw with that actor. So new neural pathways are now built on top of (or in "collaboration" with) the previous pathways that held previous knowledge. I wonder if these same neural pathways can also be in charge of knowing other names, or some other types of information. Maybe certain cells can only take on only explicit or only implicit behaviors? And if so, would there be a limit if they can take on more behaviors?

 

[atyy]

Furthermore, I understand that neurons (and groups of neurons) can have a certain amount pulses per second, but I am still unclear about whether a certain neural path can "hold" more than one learning? The way I get it so far is that learning can build on top of each other, using one learning to learn more. For example, if I meet someone who has a name similar to a famous actor, I will associate that person to all the movies that I saw with that actor. So new neural pathways are now built on top of (or in "collaboration" with) the previous pathways that held previous knowledge. I wonder if these same neural pathways can also be in charge of knowing other names, or some other types of information. Maybe certain cells can only take on only explicit or only implicit behaviors? And if so, would there be a limit if they can take on more behaviors?

http://www2.le.ac.uk/centres/csn/publications-1/Publications/scientificamerican0213-30.pdf
Brain Cells for Grandmother
R. Quian Quiroga, I. Fried, C. Koch
Scientific American 308: 30-35, 2013

The number of memories depends on how the neurons are connected, how the information is encoded and read out etc. Here is a relevant quote from the above article:

"Using statistical methods, Stephen Waydo, at the time a doctoral student with one of us (Koch) at Caltech, estimated that a particular
concept triggers the firing of no more than a million or so neurons, out of about a billion in the medial temporal lobe. But because we use pictures of things that are very familiar to the patients in our research—which tend to trigger more responses—this number should be taken strictly as an upper bound; the number of cells representing a concept may be 10 or 100 times as small, perhaps close to Lettvin’s guess of 18,000 neurons per concept."

 

[icakeov]

Fantastic article! And fantastic references to each of my questions atyy! Thanks again.

 

[icakeov]

Here is another question on the general topic above:
Are there neurons in the brain that haven't been "fired up" yet and are waiting until a specific learning is to be in line? Or neurons always firing up, but not necessarily with any useful information to retain? How does this work?
For example, when a baby is born, what "state" are all the neurons in? Are they are ALL active from the get go and start building neural pathways through the whole brain? Or is it more that certain parts of the brain are "dormant", if that's the right word.
For example, considering that explicit memories don't start forming after a couple of years after birth, does that mean that, for example hippocampus is inactive during all that time? (I am assuming that hippocampus is only in charge of explicit memory).

 

[icakeov]

Yet another question I have is about the triune brain. (pardon my ignorance if I got lot of this wrong)
Do reptiles have any form of a limbic system or is that only present in mammals? Similarly, do only primates have a neocortex, or do the rest of the mammals have a somewhat developed neocortex?
Do fish, amphibians (and so on) have a reptilian brain too? Or some form of it? Do they have anything at all similar to a limbic system or neocortex?
Now, If reptiles (or some other similar species group) only have a reptilian brain but no limbic system or neocortex, would that mean that they can't think and cannot feel? And does that mean that they (and all animals apart from mammals) don't think and don't have feelings and purely function based on survival, "reptilian" instinct?
And how does this affect memory and learning in other species? Is implicit memory stored in the "lower", reptilian and limbic structures and is explicit memory present in only the neocortex? And what about learning by imitation? Which parts of the brain can learn through imitation, and as a result, are there certain species that can learn through imitation and some can't?

 

[DiracPool]

Are there neurons in the brain that haven't been "fired up" yet and are waiting until a specific learning is to be in line? Or neurons always firing up, but not necessarily with any useful information to retain? How does this work?

All neurons are always active in the brain all the time, or else they typically die or get "pruned." Even "at rest" they always maintain some basal pulse frequency.

For example, when a baby is born, what "state" are all the neurons in? Are they are ALL active from the get go and start building neural pathways through the whole brain?

Yes

Do reptiles have any form of a limbic system or is that only present in mammals?

You ask a lot of questions here that aren't as black and white and the questions suggest. I recommend two fairly easy to read books for the lay person, Streidter's Brain Evolution and Swanson's Brain Architecture.

https://www.amazon.com/dp/0878938206/?tag=pfamazon01-20

https://www.amazon.com/dp/019537858X/?tag=pfamazon01-20

Very generally, though...

Do reptiles have any form of a limbic system or is that only present in mammals?

The best way to look at this is that reptiles have a homologue of the mammalian limbic system and this can vary from species to species.

Similarly, do only primates have a neocortex, or do the rest of the mammals have a somewhat developed neocortex

All mammals have a neocortex. The only major distinction is that Eutherian (placental) mammals have a dedicated motor cortex, or M1 region, and non-placental mammals such as the marsupials (e.g., kangaroo) do not.

Do fish, amphibians (and so on) have a reptilian brain too? Or some form of it? Do they have anything at all similar to a limbic system or neocortex?

There is a debate as to what extent the amphibian brain has some homologous features to what may be referred to as a canonical mammalian limbic system. For example, there is some evidence that frogs have a homologue to the amygdala.

And how does this affect memory and learning in other species? Is implicit memory stored in the "lower", reptilian and limbic structures and is explicit memory present in only the neocortex?

When you talk about "thinking and feeling" and "explicit versus implicit" memory, you are now venturing into the wide field of neuropsychology, where the answers are much less clear cut than anatomical considerations.

 

[atyy]

(I am assuming that hippocampus is only in charge of explicit memory).

And how does this affect memory and learning in other species? Is implicit memory stored in the "lower", reptilian and limbic structures and is explicit memory present in only the neocortex? And what about learning by imitation? Which parts of the brain can learn through imitation, and as a result, are there certain species that can learn through imitation and some can't?

Just to echo DiracPool's point that "explicit" and "implicit" are human terms, which is very difficult to generalize to animals, although it is discussed, eg. http://www.ncbi.nlm.nih.gov/pubmed/23964879 (sorry, no free full text this time). While waiting for the experts to settle on what concepts they find most general, one can say that we learn many different things, and these involve changes in different parts of the nervous system. So one may prefer to say eg. "hippocampal-dependent memory" rather than "explicit memory".

 

[Feeble Wonk]

I think it might be helpful for you to think about memory/learning/mental functions as a functional process rather than a structural one. You shouldn't think of memories or learned behaviors as being "stored" in a neuron like they're a substance that is bottled. During the learning process, it's not so much the nerve that changes as much as it is the synaptic connections. What changes is how the neuronal network functions.

 

[Feeble Wonk]

Thanks for your response Ygggdrasil,
I didn't realize that DNA can mutate within the body in its lifetime. And that it happens in neuron cells. Is this something that happens as a rule of thumb or more of a rare occurrence with neurons?

...and, for whatever it's worth, mutations can occur anytime a cell undergoes binary reproduction during the transcription phase. Cancer is an example of this of course. They're more common in rapidly reproducing cell lines, but not uncommon in neuronal tissue.

 

[icakeov]

Thanks Feeble Wonk!
The analogy of thinking of it as synaptic connections and network functions really helps. Would it be fair to think of memories as "electric charge" and network functions to a specific "installed software"? Would that be at least to a degree more analogous?

 

[icakeov]

And thanks DiracPool. I am really realizing after reading all the answers here why it is said that the brain is such a complex system.
With the way it works, it sounds like, the brain as a whole is constantly active, and depending on what environment a specific organism is in, it will learn different things, perhaps not the best learning at times when the brain is not exposed to it, but the neurons are firing regardless, hungry to accumulate learning.

 

[Feeble Wonk]

In regard to innate/instinctual behavior, you might think of the neurological function (synaptic connections) being hard wired from birth.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3337482/

 

[Feeble Wonk]

Thanks Feeble Wonk!
The analogy of thinking of it as synaptic connections and network functions really helps. Would it be fair to think of memories as "electric charge" and network functions to a specific "installed software"? Would that be at least to a degree more analogous?

I'm not sure about the "electric charge"/memory thing. Not sure I see a similarity there. But memory is a funny thing for lots of reasons, subtly different from basic learned behavior. Aside from that, there's both short term and long term memory, and both psychological and physiological components. Wiki does a pretty good job of general discussion.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3337482/

 

[icakeov]

Hi Feeble Wonk, I found this video that describes the evolution of the brain and describes neural impulses as electrical ion impulses. And also they explain that
synapses enable the storing of long term memory.

I am still trying to find a way to understand how long term memory actually gets stored. It is not "stored", and it is not analogous to an "electrical charge". And it is not stored in the neuron, but rather through the synapses, and it needs to be learned over and over again for it to become solid long term memory.
So when I think of learning as a function, I am still at a loss where and how that function gets "retained" and, for a lack of a better word, "stored"?

 

[DiracPool]

So when I think of learning as a function, I am still at a loss where and how that function gets "retained" and, for a lack of a better word, "stored"?

It gets stored as a pattern of reinforced synapses that get reinforced when reward accompanies a given behavior. Rewarded behaviors are conditioned to a "go" mechanism that facilitates the expression in the musculature of such rewarded behaviors. Punished behaviors are conditioned to a "stop" mechanism which inhibits the expression of said behaviors. Behaviors that are neither reinforced nor punished typically get "extinguished" through atrophy of their synaptic connections.

 

[Feeble Wonk]

It gets pretty complicated really. There are a lot of feed back mechanisms with various neural connections between different areas of the brain. There's biochemistry involving neurotransmitter release that can trigger or inhibit nerve impulse transmission. But, the general idea is that as you learn something (how to respond to a given stimuli, motor skills, etc.), changes develop in the synaptic connections within the brain to facilitate the learned behavior more efficiently... more reflexively. Some nerve cells do change their shapes somewhat in the process, but it is not that structural change that achieves anything. It's the new synaptic connections that develop that change the function of the brain.
Having said all of this, it seems to me that you might be struggling with a deeper more subtle idea regarding memory, which is the experience of mental "qualia". That starts moving into a philosophical discussion regarding the nature of consciousness, but we're really supposed to avoid that on this forum. You can google "qualia" to get a better idea of what I'm referring to. You might pay particular attention to the "neurobiological blending of perspectives" portion if you prefer to concentrate on the neurophysiological subject matter.

 

[icakeov]

Yah, I would love to avoid going into philosophy on this too.
I am just trying to wrap my head around understanding the retaining of memory.
DNA holding information is very clear, how it "stores" it and where and how it distributes it and creates new cells and so on.
But when it comes to memory/information, it seems much muddier, since clearly, it is a very complex system. So far, I am understanding it as "complex circuit information patterns of reinforced synapses" that can get reinforced or not, depending on stimulation.

 

[Feeble Wonk]

That's the nuts and bolts of it, yes.

 

[DiracPool]

So far, I am understanding it as "complex circuit information patterns of reinforced synapses" that can get reinforced or not, depending on stimulation.

That's pretty close. Sort of concluding all the discourse above, the best way to look at brain function is as a system that internally generates its own pattern structures based on the very complex arrays of synaptic "weight" distributions between and among the neurons. The brain is organized into hierarchical systems where these dynamics unfold. We can break these down into simplicity as constituting 3 basic layers or levels; macroscopic, mesoscopic, and microscopic. Macroscopic deals with the dynamics between major brain regions, or what we call "interareal" dynamics, mesoscopic dynamics deals with the interactions within any given cytoarchitectonic brain region, such as visual cortex V1, V2, TEO, TE etc. Microscopic dynamics deals with interactions between neurons within and between individual cortical "columns" and mini-columns, as it were.

The collection of all these regions is always active all the time and is doing something...What it is doing depends on the situation. If you are sitting around on the couch like a couch potato, it may be self-generating random internal patterns that you interpret as daydreams. If there's a knock on the door it's going to trigger a locomotor chaotic attractor to ambulate you towards that door. If your limbic system is sensitized because you're hungry and you see a food ad on TV, then you are going to ambulate toward your fridge. If you are not hungry then that ambulatory attractor will not be triggered.

To put it simply, the brain does not simply "respond" to stimuli as in a stimulus-response paradigm, the brain is always creating something internally regardless of what happening in the environment, even if that something is just sitting on the couch. It will expend a great deal of energy and glucose just to watch the latest "Blue bloods" episode. And if no other stimuli is around, it will create it's own patterned "thoughts," so to speak. But typically, what it does it churn it's own wheel in a direction that is fed to it by external sensory stimuli. In other words, the brain is not dependent on sensory stimulation to drive it's dynamics, it can do just fine without it. But when that sensory stimulation comes in, what it does is influence/direct the "tornado" of chaotic activity that is already self-generated in the brain to in order to trigger an appropriate chaotic attractor that has been reinforced/rewarded in previous experience to deal with the current situation.

 

[SeanS6]

The understanding of how the brain does what it does is at the alchemy stage. A proto-science if you like. You can reasonably take the position that each of the 100 billion neurons in the brain can store only about 1 byte. In which case a current computer you could buy for less than $20,000 is as powerful as the human brain, however with no clue as to the algorithms to run on it. At the other extreme is Penrose's quantum mechanic view of the brain in which case emulation with even the most powerful digital computer would be hopeless. There is some evidence that particular biochemical molecules have been evolved to have very specific quantum behavior.

 

[icakeov]

Here's another question about the brain:

I wonder if there has been any research in figuring out specifically which parts of the brain are involved in the processes that allow humans (and some other social animals) to have the "theory of mind" ability? Would that be only the pre-frontal cortex or some other parts too? (including the amygdala of course)

Also, humans clearly have the ability of performing high end rational, computational functions, and the ability to ask and answer the question "why", and be able to say things like "I know that you know that I know". Have by any chance these functions been assigned to a specific area in the brain that only humans (and no other animals) possess?

 

[DiracPool]

Would that be only the pre-frontal cortex or some other parts too? (including the amygdala of course)

The amygdala is, at best, distally related to any "theory of mind" capacity. You're more on the mark with the prefrontal cortex. Again, as I've said in other posts, it is not helpful to try to compartmentalize brain functions with specific regions. In the literature, we call this "localizationalist" models of brain function. "Theory of mind" models are well-presented in the literature, but they are at present speculative enough to be be relegated to the psychological journals.

 

[DiracPool]

And thanks DiracPool. I am really realizing after reading all the answers here why it is said that the brain is such a complex system.
With the way it works, it sounds like, the brain as a whole is constantly active, and depending on what environment a specific organism is in, it will learn different things, perhaps not the best learning at times when the brain is not exposed to it, but the neurons are firing regardless, hungry to accumulate learning.

Yeah, another book I recommend is Walter Freeman's "Society of brains."

https://www.amazon.com/dp/0805820175/?tag=pfamazon01-20

It was actually (still is) a favorite book of mine. I held out to get the paperback version cause I'm a cheap a#$. But I did meet him at a conference in 2003 in Memphis and had him sign the book. Of course, somehow I lost the book.

The principal message in that book, though, is that the brain is a dynamic system that creates it's own activity, it doesn't necessitate external stimuli for the most part. What the brain does is USE environmental stimuli to drive behavior. This as opposed to a model where the environmental stimuli DRIVES behavior. This is an important distinction.

 

[icakeov]

Basically, since it is impractical to segregate brain functions into specific brain areas, because they are so deeply integrated throughout the whole brain, perhaps it would be a bit more descriptive and helpful to say that for this specific example, it is the "socially intelligent species" that have developed brain capacities of "theory of mind" and "empathy". Keeping it descriptive like this could be much more practical than trying to point out a specific brain area, except of course, for the prefrontal cortex, as one example of a brain part that performs very specific task in certain species.
And thanks for that book recommendation, I will check it out, sounds really interesting and exactly what I am looking for to answer all these questions. :)

 

[icakeov]

Here is another thing I am curious about:
Instant traumatic emotional conditioning. If it takes a brain many reinforcements to learn something, how is it that when it comes to traumatic experiences, something can be conditioned in an instant, for life?
Is this some kind of a big "cluster" of reinforced patters firing back to back a thousand times in a few seconds, creating a very strong neural pathway?
Or is there some other procedure, perhaps a simpler one, at work?

 

[atyy]

Here is another thing I am curious about:
Instant traumatic emotional conditioning. If it takes a brain many reinforcements to learn something, how is it that when it comes to traumatic experiences, something can be conditioned in an instant, for life?
Is this some kind of a big "cluster" of reinforced patters firing back to back a thousand times in a few seconds, creating a very strong neural pathway?
Or is there some other procedure, perhaps a simpler one, at work?

I think this is not fully understood. However, simple considerations like what you mention suggest there are, as said before, different types of learning in different parts of the brain. They differ in whether they constantly store memories, or only when memories are "emotional" enough, as well as in how many times something has to happen before it is remembered, or how quickly it is forgotten.

You can google "one-shot learning" to see what you get. There are animal models too, eg. the link given in post #7.

 

[icakeov]

Here's another question, this one is more in lines of memory/learning/communication transfer between different species.
Although we can't "talk' to whales, dogs or cats, we clearly are able to communicate with them on some level. I am imagining that there is certain types of interactions that we share with animals, perhaps on an emotional level? Or authoritarian level?
I've read stories of children running away from home and being adopted by wolves for a few years. And similarly, humans have pet animals that they coexist with.
But can any of this "co-living" be labeled as proper "social communication and/or interaction"?
I found this chart that seems to be pretty descriptive:
https://en.wikipedia.org/wiki/Social_relation
Where on this list would the interaction between humans and their pets be? And vice versa, if a human lived amongst animals (another example that comes to mind is that guy that hangs out with lions and hyenas)
Even thought we can't pass on mathematics on to our pet cats, can we pass on behavioral learning. Can we "compare" or "equate" the learning cats get to the ones humans have. Do they have same (or similar) types of neural pathways that deal with that kind of learning? Or are they in their "own world", acquiring type of learning in their neural pathways that is completely different from ours? I would imagine it would be basically the same, as all mammals evolved to have the amygdala, unless its function drastically changed since we parted in evolution from our ancestors.
On that note, I can imagine that cetaceans might have a way of thinking and communicating that is completely foreign to us and we couldn't understand even if we tried, mainly because our brains don't have the cortex evolved in the same way as them.

 

[DiracPool]

Where on this list would the interaction between humans and their pets be? And vice versa, if a human lived amongst animals (another example that comes to mind is that guy that hangs out with lions and hyenas)
Even thought we can't pass on mathematics on to our pet cats, can we pass on behavioral learning. Can we "compare" or "equate" the learning cats get to the ones humans have. Do they have same (or similar) types of neural pathways that deal with that kind of learning? Or are they in their "own world", acquiring type of learning in their neural pathways that is completely different from ours? I would imagine it would be basically the same, as all mammals evolved to have the amygdala, unless its function drastically changed since we parted in evolution from our ancestors.
On that note, I can imagine that cetaceans might have a way of thinking and communicating that is completely foreign to us and we couldn't understand even if we tried, mainly because our brains don't have the cortex evolved in the same way as them.

I think you're pretty much on the mark here. Humans have the ability to use a formal structure to perform operations on recorded manifestations of stimuli in an unhindered fashion. This is what gives rise to language, art, mathematical ability, and the "texting" phenomenon in teenagers. Non-human animals do not have this capacity, but they pretty much have everything else.

 

[icakeov]

I'm pondering another angle to this thread.
Which animals have the capacity to culturally transmit information?
I saw a reference from the "thinking ape" book that intelligence is ability to respond flexibly to new or complex situations, to learn and to innovate, and social intelligence the ability to pass on to others this new innovated information that is not genetic.
And currently there are a few identified socially intelligent animals besides humans, such as cetaceans, apes, elephants, then there is crows, rats, more birds. Even fish seem to be able to do simple copying behaviors, such as "follow" the movement of their school and retain that information, which I imagine wouldn't necessarily fall into the category of "intelligence" as they don't necessarily respond to complex situations nor innovate.
I am wondering if there is any information out there that describes a necessary prerequisite for an animal species to be able to start culture transmission amongst their brains? For example, certain part of the brain that would have evolved at one point, without which no animal can stand a chance to retain and transmit information in their community through generations?
Hope I was clear enough with this question. Thanks again :)