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Saturday, December 5, 2015
Brain / Mind ... Science ...

Our brains are obviously very important to all of us, and society is thus making a lot of effort to get to know it better. Human brains do a whole lot of things, but one of the more interesting things that they do is to retain and make available a mental replay of certain thoughts, feelings, perceptions and experiences from the past. I.e., our brains give us our memories. Human memory is a wide-ranging thing. In addition to giving us a “video replay” of sorts for past experiences, it stores facts, skills, emotional impressions and various other things on both a conscious and sub-conscious basis (e.g., we pick up a lot of fears, attractions and various other tendencies without being aware of them, even though they will influence our behavior nonetheless). So, the human memory has been the subject of a lot of research effort on the part of science and psychology.

Since the brain and its interactions with our bodies and our lives is such a complicated subject, our species has found many ways of studying it. On one level, we address our memories from the perspective of familiar conscious impressions and experiences, along with the behaviors that result from them; this is generally the realm of the psychologist. Even before Freud, the notion that our memories are key to determining our current behaviors and our feelings of contentment or discontent with our lives has been a key principle in the practice of psychoanalysis.

Freud expanded the concept of memory with the realization that a lot of our memories lie beneath the surface of conscious awareness, and yet they play a critical role in directing our behavior. Psychology has come a long way since Freud, and today uses better, more scientific methods to record and analyze human behavior patterns relative to our current environments, along with our on-going mental states and our memories of past events. But memory remains a key feature in the efforts of psychologists to better understand our brains, from a “broad-strokes” perspective based on the observation of human behaviors and mental states (and how we express them in words and other emotional responses).

If psychology is the broad-strokes approach, neuroscience is the “under the microscope” close-up method of studying how brain, body and environment interact. Neuroscience gets down to the nitty-gritty of individual neuron cells and how they somehow team up in mass to give us a world of vivid perceptions, deep feelings and complex behaviors (as well as the basic job of keeping us alive!). Actually, neuroscience as a whole is still pretty far from crossing the bridge between watching neurons and groups of neurons send signals to each other, and understanding just why we have the feelings that we feel, perceive the things that we perceive, think the thoughts that we do, etc.

More and more neuroscientific research purports to link certain brain areas and brain activities with a variety of mental and social tendencies such as violent behavior, religious belief, sexual desire, fears, habits, etc. But many of these associations are still relatively crude and controversial, and there is still no overall working model of the brain. With 86 billion neurons interacting through a variety of means (including both electrical signaling and chemical interactions), human science, even with its fantastic scanning, computing and data storage devices, is probably still a ways from understanding the brain just as well as it understands a smaller and simpler organ like the liver or thyroid.

So, it may not be all that surprising to find out that neuroscience still isn’t quite sure about how the facility of human memory works. We do know that the primary “unit” or “mosaic chip” of brain activity is the firing of a neuron, which involves a series of ion chemical reactions between the neuron and the fluid surrounding it that causes an electrical impulse to travel from one end of the cell to another. Neurons are generally long and wire-like, and they interact with other neurons via “synapses” at their ends. A neuron is affected at one end by at least one, but generally very many other neurons, via the proximity between their synapses; when enough synapse activity is happening in the neighboring neurons at that end, the individual neuron will “decide” (via some electro-chemical computing device formed by the proteins and other molecules within it) to activate itself and send an impulse down its spine, to its opposite end. At that opposite end, the neuron’s synapses will then activate and in turn influence the neighboring neurons at that end to possibly fire off themselves.

How then are memories formed and stored across an organized series of thousands, millions or even billions of neurons and their extremely complicated synapse interconnections? The generally accepted paradigm right now is based on the concept of “cell assemblies“, groups of cells that fire off together when a person perceives the event or repetition of events (e.g., when you are trying to learn something or memorize a complex set of facts) on which the memory will be based.

When something is picked out by the brain to be remembered (there is obviously a mechanism in the brain that decides what is to be remembered and what is not; you usually will not remember what you saw on your way to work most days, but if you see a shooting star streaking across the early morning sky, you might remember that), the “cell assembly” members that went off during the event manage to keep on firing together for a while, and firing quite strongly. It is believed that when a group of adjacent neurons fire together, they “wire together”; i.e., they adjust their synapses to become especially sensitive to each other. So, if some other thought or perception triggers off one part of the cell assembly, the whole thing starts buzzing; i.e., you have been reminded of that memory and all of the details of it (that you remember).

In sum, “cells that fire together wire together”; and wired-together cells seem to be the basis of memories. By the same token, when certain cells of the memory assembly are frequently triggered by some other brain event (because most neuron and neuron clusters are not used exclusively for one function, e.g. remembering your car’s license plate number; they often become part of a multitude of varying coalitions with many different objectives) while the other parts of the memory cluster stay dormant or fire later on, the overall memory can start to erode and fade. The saying for this is “out of synch, lose your link”.

E.g., if you build a memory of a favorite singer, but some years go by and that performer fades from public view and you don’t hear his or her name mentioned for a while, your memory of that artist might start to degrade; recently this happened to me regarding Jackson Browne. In the 1970s I was a big Jackson Browne fan, but he has since faded from fame; and so, not long ago I started thinking about one of his songs, but I could not place his name. I remembered some of his other songs (like “The Pretender”) and I even remembered what he looked like (back in the 70’s anyway — like his face was on “Doctor My Eyes” album). Part of my memory assembly for Jackson Browne was intact, but a big part of it — regarding his name — had uncoupled. Eventually I came across a reminder (and I had that “OHHHHH YEAAAAAA” moment), and the original neuron cell assembly in my brain for Jackson Browne was repaired — for now, anyway.

This all sounds pretty good . . . but not every neuroscientist agrees with the primacy of the “wire together, fire together” theory of memory based on the adjustment of synaptic sensitivities or connection strengths. It is often said by neuroscientists that the brain does NOT work like a computer, and the memory mechanism is given as a key example. Computers store facts by using a lot of little metallic segments that can either be given a permanent (although changeable) charge or remain un-charged. These are the digital “registers” of computer processors (in the original computers these were actual magnetized rings that could flip one way or the other based on their magnetic charge, but in today’s sophisticated devices the digital registers are tiny bits of metallic or magnetic material on a silicon chip). Obviously, nature and humans appear to be using two different philosophies on how to store information.

There are pros and cons to each method. In computers, each register is generally devoted to only one purpose; e.g., it may team up with a handful of other registers to store the 6th digit in one of your credit cards. In the brain, a particular neuron synapse connection could play a role in a number of processing functions in your brain; e.g. if it relates to the color green, it might be part of your memory of guacamole and of Christmas trees, among many other things. This arrangement would seem to be more efficient in a way — it seemingly lets the brain pack a lot more memories in given a limited number of neurons and synaptic connections. The computer, with its rigid exclusivity of how registers are used, would seem to be limiting itself. (Interestingly, the brain’s memory is seen to work somewhat like a hologram, given that a holographic image is reflected from a “memory plate” from which every point on the plate contributes to every feature, e.g. the nose on a hologram of Abraham Lincoln’s face, and every feature in the image of the face is made up of light coming from every point on the plate).

However, there is a problem with the hologram-like way that the brain supposedly stores memories, one which I have already hinted at. And that involves how long and how well the memory information will last. In modern computers, digital memories are fairly secure and unchanging, so long as the processing hardware and software is maintained. Unless an effort is made to erase the memory and re-use the registers for some other information (say that the memory device is full — which in this age of cheaper and larger memory capacity is becoming less and less of a problem), newly inputted information needs to find a currently unused registry area to be stored in. Thus, stored information is not influenced by other data that is coming in. By contrast, in the human brain, every “memory assembly” is subject to being influenced by new information, which is continually arriving so as to help us survive in a challenging and constantly changing environment.

And that is a big reason why humans generally do NOT have “steel-trap memories”, and why testimony at jury trials can be so contradictory and confusing (even when all witnesses are being totally honest). If you are at an office party and say something bad but not threatening about your boss to a co-worker over a drink, your co-worker will probably forget it by next week. By contrast, if you write the same thing on Facebook, you could get into big trouble down the road, if your boss happens to come across your comment. It’s taking a while for our species to adapt to the fact that “computer brains” aren’t like our own brains.

But, as I said before, memory is a rather wide-ranging topic, and it includes a lot more than the declarative/episodic memories that I just discussed. Our memories of past events and observations often aren’t very accurate; but arguably, other forms of human memory are a lot more firm and unchanging. This is especially true when human survival is at issue; for example, we don’t seem to easily forget taste sensations. Even as we age and our brains get weaker, we don’t seem to have a problem distinguishing what is edible as food, and what is foreign or even poisonous (i.e., substances with bitter or strange tastes such as gasoline or berries from ornamental plants like the wisteria).

Also, we normally don’t get very confused about what numbers are; when we see four objects in front of us, we think ‘four’ pretty quickly, and don’t usually scratch our heads about whether its seven or two. Many people also have very good memories about location (although I don’t); if they’ve been to a place once, they can find it again ten years later. And although emotional memories can and do change over time, when left alone they often stay intact for a long time (e.g., I still feel a bit of fear and dislike when thinking about people who bullied me back in grammar school, even though I realize that they are now old folk like me and are very unlikely to bother me at this point; I’ve never gone to a high school re-union partly because of this, and I’m struggling with the idea of giving it a try next year at the 45th). So, perhaps there is some part of our brain that stores memories more like a digital computer does?

Interestingly, I recently came across an article in Scientific American that claims just that to be true. The article title says as much: “Memories May Not Live in Neurons’ Synapses”. A U.C.L.A. neurobiologist named David Glazman has been conducting research on some simple life-forms like slugs, and found that their memories (simple though they might be, such as which direction food or water might be) could be temporarily disrupted by tampering with the neuron’s synapses; but once the synapses grew back, the memories returned. This points to more permanent changes made within the body of the neuron — somewhat akin to the charging or non-charging of a metallic register on a computer chip. Glazman feels that this change could be effected through DNA mechanisms, such as the “epi-genetic” methylation methods that can turn on, turn off or regulate how a protein-producing gene responds to its environment. A variety of previous studies (e.g., here and here) have suggested that gene expression and methylation play a role in memory formation and retention.

Another recent article on the Nautilus web site pretty much agrees with this, and its title is even bolder: “Heres Why Most Neuroscientists Are Wrong About The Brain“. The author (C.R. Gallistel, a professor of psychology and cognitive neuroscience at Rutgers University) says that “experimental results published last year, from a lab at Lund University in Sweden . . . suggest the brain learns in a way more analogous to that of a computer: It encodes information into molecules inside neurons and reads out that information for use in computational operations.” Dr. Gallistel makes a point about numerical memory similar to what I just discussed (OK, maybe I got the idea from Dr. G):

“recently, I asked about 20 leading neuroscientists at a workshop at the Massachusetts Institute of Technology . . . how one could store numbers in synapses, several became angry or diverted the discussion with questions like, ‘What’s a number?’”

Even more:

“Most neuroscientists accept that the brain also computes in some sense. However, they think it does so by modifying its synapses, the links between neurons. The idea is that raw sensory inputs, which initially produce incoherent actions, help the brain change its structure in order to produce behavior better suited to the experienced environment. The brain learns because experience molds it, rather than because experience implants facts. The problem is that experience does implant facts. We all know this, because we retrieve and make use of them throughout the day.”

Even though I’m not a scientist and I don’t possess anything near the neural capacity needed to be a neuroscientist, I have an opinion about all of this, as follows. The human brain has probably evolved to use a “best of both worlds” approach. Many aspects of memory are probably stored in the brain through chemical changes in the synapses, changes that affect their connectivity. That is probably a quick and dirty way to start the memory process, one that doesn’t need much time or chemical energy. However, the most important stuff needs to be permanently stored, and for that, the slower and more energy-burning methods of DNA modifications are probably used with neurons that are then devoted mostly to a particular type of brain processing (e.g., food taste and smell, or high-level abstract reasoning).

It has long been known that a synapse can be affected by its neighboring neurons in two ways. The standard path involves releasing or sucking in neurotransmitters which bind to receptors on a synapse, thus encouraging or discouraging the neuron to start firing its electrical signals; but another path involves neurotransmitters which cause some sort of chemical change to the neuron itself. The former path uses ionotropic receptors, whereas the latter pathway involves metabotropic receptors. Some synapses and neurons might be more “ionotropic”, while others might be more “metabotrobic” (and thus computer-like).

According to an article on these receptors, “ionotropic receptors act very quickly . . . metabotropic receptors, on the other hand, take a little longer ‘to do anything’ depending on the number of steps (secondary messengers), required to produce a response.” As I said, it appears that millions of years of evolution inadvertently crafted a “best of both worlds” brain for us. Our memory facilities have a lot of problems relative to what we want them to do for us in the modern world. That’s why we are building such fantastic information machines and systems such as smart phones, laptops and “the cloud”. Oh yes, and police body cameras. But without the fantastic capacities of the human brains that designed and set up these systems, they never would have existed.

So, hats off to the human brain (but not for too long, as we want to keep the head and brain warm during the upcoming winter season). And thanks for the memories!!!

◊   posted by Jim G @ 9:30 am      
 
 


  1. Jim, How to approach this post is a kind of a conundrum as far as I’m concerned. On the one hand it seems to me that a clear distinction should be made between a couple of things: 1) The differences between psychology, psychoanalysis, and neuroscience. Is it possible to keep the three separate, even while they each handle and deal with different areas of the human being? Then, on the other hand: 2) There’s no doubt that the physical brain must be involved in how the human being “works” and thus I find myself wondering how to separate the 3 areas yet keep them connected to the brain.

    But I don’t know if it’s possible to separate out the “two hands” as above. But as I read, I couldn’t help but find myself thinking that neuroscience, psychology and psychoanalysis are ach very different and handle very different (deeper into the human person?) areas of the human being. Maybe that’s it: Neuroscience may be on the surface (the tangible), psychology may be the “middle ground”, covering some of the tangible and some of the intangible, while psychoanalysis deals almost exclusively with the intangible. Can’t say I’m right; more like I’m just wondering if that might be a possible separation that works for the person.

    But I find that as I read, I keep feeling that while the 3 were mixed together, they still need a separation. Perhaps it would help if neuroscience kept to the brain itself, psychology kept to dealing with behavior and its cause, while psychoanalysis dealt with the deep unconscious and its effect on the human. Perhaps separating these 3 out in such a way would then lead to how the proper functioning of the brain is necessary for the human to express any of the intangible.

    Furthermore, I wondered if it might be the intangible that is missing from artificial intelligence and/or computers that work like/better than a human brain.

    This is a difficult subject, altho a lot of people do not want to separate out the 3 areas of the human being that are separate yet somehow joined. But it would seem to me that getting some agreement on the “order” of how the brain works in a general way, i.e., neuroscience, psychology, psychoanalysis, would vastly improve the study that’s being attempted (and so often somehow just not “hitting it right”) by scientists, psychologists, and psychoanalysts. MCS

    Comment by Mary S. — December 5, 2015 @ 3:46 pm

  2. Jim, It occurs to me that psychiatrists might just be the “link” between neuroscience and things psychiatric. Psychiatrists are medical doctors who may and certainly *do( give out medications for mental issues. Thus, these medications have a direct effect on the brain and its neurons. So that may be the group that would more likely be a closer connection to neuroscience, the brain, and how the brain affects human behavior, etc. MCS

    Comment by Mary S. — December 6, 2015 @ 10:59 am

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