Wednesday, December 11, 2013

Dopamine the Bus Driver



[correction included]



What is dopamine? What, for that matter, is a neurochemical (or neurotransmitter in this case)? Let's do a brief refresher from Neuroscience 101

You have billions and billions of these:



Neurons, as you'll recall, store your "data" (memories, information and so on). You'll see axons and dendrites there as well. Axons pass on information to other neurons and dendrites are on the receiving end. At the junction of an axon and a dendrite you have a synapse (and recall that you have somewhere around a hundred and fifty trillion synapses). A synapse looks like this:


That's somewhat simplified of course but I can assure you that it is a complicated piece of business, a business that takes place over trillions and trillions of synapses in your brain trillions of times per second for every minute that you will draw breath in your lifetime. The business we're talking about is the transfer of signals from neuron to neuron throughout a given pathway. In other words, if these transactions don't take place, then the information from any given set of neurons isn't "brought on board" whatever it is "you" are trying to do. These ridiculously fine transactions (a synaptic cleft is only about 20 nanometers across and the neurochemicals themselves are very fine indeed) govern a massive amount of brain activity which in turn governs "you". 

So that's a neurotransmitter and dopamine is just one such transmitter of about a hundred but, as we'll see, it's a very major one when it comes to animal and human behaviour. Let's review the dopamine pathways. They look like this:


We briefly touched on that in Neuroscience 101 and now it's time to look at it in a little more detail. Dopamine originates in the Ventral Tegmental Area, a small nodule in the limbic system . The limbic system lies between our more elementary "lizard brain" brain stem hardware and our more highly evolved cortex area. The VTM's job is pretty elementary and it acts in accordance to messages from other more prominent parts of the limbic system. Aside from very advanced practitioners of meditation (whom we'll look at in a fascinating future post), this part of our brain is quite "off limits" when it comes to our conscious control. There's a potential kind of "back door" access to the VTM - aside from meditation - that could initiate a modicum of control but we'll touch on that at the end when we look a bit more at dopamine's complete circuit. (correction notice)

From the VTM, the circuit heads to that little bit of hardware that seems to come up in every discussion on human behaviour, the amygdala. We looked at this highly influential little brain nodule in the previous post and examined a bit how much power it has over our perceptions of and reactions to the outside world, and hence our behaviours. We established then that the amydgala is a major driver of our actions. So if the amygdala is a big part of our actions and dopamine is a part of what drives that, then dopamine is part of what controls a very deep part of who we are and what we do. 

Another key destination is the nucleus accumbens. Research has indicated that this nodule (of which there is a left and right in the respective hemispheres of your brain) has an important role in pleasure; including laughter, reward, reinforcement learning, as well as fear, aggression, impulsiveness, addiction and the placebo effect. So again, we see dopamine plays a role in a key region of many of our most human attributes (as well as those in animals; we just take those to higher and more sophisticated levels).

But there's more.

You can see that the end destination of dopamine is the frontal and prefrontal cortex. As I mentioned in Neuroscience 101, if you want to know where "you" are, it's believed by some neuroscientists to be "there" (though recent evidence now puts this in some dispute). It is also in these areas that we experience theory of mind, the uniquely human abilities involved in such things as understanding how others are thinking, our predictive powers and so on. This is, if all goes well, what makes us "human". As well, you can see it's these areas that are responsible for things such as planning and judgment (something we touched on in two different case studies in the previous post). As dopamine is a major influence on what goes on in there, in order to better understand human behaviour (or your pet's behaviour for that matter) and because the neuroscience of human behaviour is the whole point of this blog, we'd better look at this much closer. 

The Reward System


The dopamine system is very often referred to as our "reward system". So let's examine a bit about what's meant by that. 

As I said in Neuroscience 101, dopamine is one of the most widely studied and understood brain systems in neuroscience and there is little doubt as to what forces it has over animal and human behaviour. Dopamine is very strongly implicated in such basic human and animal drives as motivation, pleasure and euphoria, the fine tuning of motor function, and perseveration. We'll look at just motivation and pleasure today. 

Feeling motivated? Feeling "turned on" by what you do? Feeling "driven"? That's dopamine at work in your emotional centre and in your planning and judgment centre, the frontal and prefrontal cortex. Not feeling those things? That's dopamine not working so well (for reasons we'll touch on at the end). The same with feelings of pleasure - that's dopamine telling "you" that whatever you're doing, it feels "good" which is why dopamine is a major part of our sex drive. The pleasure you feel in sex is derived in part, though not all (we'll examine the other factors in a later post), from a dopamine "hit". Dopamine also can - emphasis on can - keep you motivated to keep seeking sex (often to disastrous results). Why it sometimes doesn't is something we have to leave aside for that later post. 

The evolutionary idea is, you see, to "reward" you with a deliciously good feeling for something beneficial to your survival to ensure that you'll be motivated to not only do that again but to keep you focused on it (and motivated and focused and motivated and focused and motivated and focused in the case of addictions). 

How much does dopamine drive our motivations and pleasures? Robert Sapolsky is a world wide recognized leading expert on dopamine and behaviour so I'll let him tell it. As Sapolsky explains;

dopamine levels increase as soon as we start anticipating a reward. Once the dopamine starts flowing, monkeys and people will work and work and work in expectation of receiving a "treat" at the end of their toil. For monkeys, the anticipated reward can be a grape. For humans it can be a pair of sneakers, a shiny car (you'll recall the example I gave in Neuroscience 101 of a "decision" to buy a new car), an MBA that might lead to a high-paying job, early retirement, a couple of minutes of entertaining diversion, a few seconds of sexual gratification, or the promise of eternal salvation. 

A brief five minute video of Sapolsky explaining this in slightly more, and very fascinating, detail can be found here

I've said that there are parts of neuroscience that are well known and parts that aren't so well known. The dopamine reward system is very much on the known side of the ledger. Literally thousands of experiments and studies done over very many decades on all manner of animal and human research subjects have very thoroughly cemented dopamine's role in our behaviours. As our dopamine system is indistinguishable from that of rats, cats, dogs, primates (or moose as my humorous lead image shows) and so on, researchers can see that our behavioural drives are not all that different from, for example, a rat driven to go through great lengths to press a lever again and again to receive a reward. What's fascinating (and which Sapolsky explains in the video) is that this drive increases when "maybe" variables are introduced. Which is literally what keeps the city of Las Vegas in business

But while we may share a dopamine drive with the average lab rat (and all other mammals), human brains have some additional hardware, that being our vaunted frontal and prefrontal cortexes which is why we're (probably) not going to be motivated by a grape or a bit of rat food like our lower mammal cousins are. It's these so-called regions of "control" that keep us going like rats on a wheel in pursuit of things like sneakers, cars, degrees, trophy wives (or husbands) and all our other "higher" human desires. 

So when we're driven to acquire something - be it an object of desire, money, a sex partner (or companionship) - dopamine is a very large part of what's going on and your drive to achieve goals in life, if it's functioning "normally", is your dopamine reward system.

But the dopamine system is a "blind robot" so to speak. It has no sense of judgment. Hence it will drive you to achieve virtually anything. Which is why dopamine is highly, highly involved in virtually all addictions (including your shop till you drop addiction, ladies, or your manly pursuits, gents). Not only does it have no innate judgment, it impairs yours (as witnessed by its influence on your judgment and planning centres in your brain). 

Is our "highly sophisticated" efforts of planning and judgment merely at the behest of a simple, autonomously running neurochemical? Dopamine won't have complete control - there are other factors - but enormous amounts of research indicates that it does indeed play a major role. This is what I mean by saying we don't really "drive our bus". That all happens in regions that are not only below our conscious awareness but well below our levels of control. 

We're running up to the end of our time today so we're going to have to leave our look at dopamine and addictions of all kinds for the next post. 

Now, I said that there was a "back door" access to the VTA from which dopamine originates. This suggests that there is a modicum of control that we may have over our dopamine system (and thus "us"). This comes from the fact that the reward centre is not strictly an "A to B" road, but one of a loop of output and input. Inputs come from areas it affects and for an idea of how much control this may have, and thus what you may have (as I promised), we have to look into the human species' "social brain", the most highly evolved such area in the animal world. I also said we'd look at why we're sometimes under-motivated and why dopamine may not be "floating your boat". It's a bit complex and a little dicey to explain, but we'll have a go at it. But that, my friends, is for another day. First, however, we're going to look more into dopamine and addictions in another post of case studies coming up in the very next post. 

Correction notice: I initially incorrectly said that the VTM is located in the brainstem when in fact it is part of the limbic system. My apologies. 

Sources:

Too many to list, virtually all of them scientific research papers like this one.The works of Sapolsky are a good place to start for further reading. As always, I have to thank Robert Whitaker, his works and his encouragement over the time I've known him. 

Tuesday, December 3, 2013

The Neuroscience of Behaviour - Some Case Studies

Examples are always a good way to understand complex issues. What we've looked at so far - a bit of a look at the neuronal circuitry of brains, and in particular the human brain - is a bit complex for sure and there are, for most people, some difficult concepts to wrap one's head around. So we'll look at some case studies in which severe behavioural changes were found to be the result of not being morally "bad" or "evil" but because of how specific brain regions had been negatively affected by factors outside of the person's conscious awareness or control. This will give us a more concrete way of understanding brain functions and behaviour. 

Before we continue, however, a few key points to keep in mind.

Each Brain is Different:

Because of genetics and brain developmental responses to environmental conditions, every brain will develop a little differently. This is even true with very elementary brains such as those found in a bee! So it's especially true with our highly evolved and complex brains. 


The Concept of Differing Realities:

By "reality" I don't mean whether a tree is a tree or is just an "illusion". We have objective methods of measuring physical objects and can agree on what they are (in physics terms). No, what we mean here is that because each of our brains are different, each brain will "assemble" what the five senses take in a little differently and thus we will all "see" - IE: perceive - things a little differently. We'll look more into the fundamentals of this later but this is an important fact to bear in mind for now. We may both see a tree, but our individual perceptions of that tree may well be different on many levels. This is well understood by modern science and is no longer in question but we'll save a more detailed look at this for another day.

Brain Regions and Behaviour:

There are, as we briefly looked at in Neuroscience 101, many microscopic components and larger components (assembled from the smaller components) in any brain (animal or human). Each region will have a basic responsibility such as the amygdala for emotions and the basal ganglia and cerebellum for motor movements (all your physical abilities) as two relatively straight forward examples. Other regions will be responsible for higher functions like reasoning, judgment and so on. It is these components and how they work in concert or not that play very large roles, as we'll see, in driving our behaviours. 


These are the basic premises for the neuroscience of behaviour that we have to keep in mind. And with these in mind, let's dive into some tangible case studies.

Phineas Gage:

We're going get two birds with one stone with our first case study. For one, it'll give us a bit of a look into and a lesson about the history of neuroscience and two, we'll see how damage to specific brain regions radically altered a person's character and behaviour. 

The story of Gage is one of the most studied and cited cases in neuroscience history. When you read the remarkable story and see the illustrations, you'll see why. 

This is Phineas Gage, a railroad foreman from the mid-nineteenth century, and in his left hand is a tamping rod that blew through his skull as the result of a mistimed explosion.  




The tamping rod entered through his left cheek and into his brain where it took out a good chunk of his frontal lobes as we can see in this computer recreation of what happened. Remarkably, 
Gage survived.



While Gage the living, breathing, blood pumping body survived, Gage the person did not. His behaviour radically changed following the accident and his recovery. Prior to the accident he was widely known as, in the words of the doctor who handled his case, "possessed of a well balanced mind, and looked upon as a shrewd businessman, very energetic and persistent in executing all his plans of operations". Friends, acquaintances and coworkers knew him to be polite and well spoken and an excellent and responsible foreman on his railway crew. His employers regarded him as "the most efficient and capable foreman in their employ". After the accident he became profane, wild, sexually out of control, and with little control over his actions and almost all chose to avoid him. He became so unreliable that his employers could no longer keep him. 

While his body lived, in the words of those who knew him, he was "no longer Gage". He became a completely changed man. 

What was lost when the tamping rod took out a portion of Gage's brain were areas in the prefrontal cortex, an area critical for reasoning and judgment (which we'll look at in a little more detail shortly). With this region no longer part of Gage's inner galaxies, he could no longer regulate the animal passions welling up from lower brain regions. 


The Man on the Clocktower:

Some of you may recall from the post Why? that I asked why a bright, educated, gainfully employed bank teller and church going man with no previous history of violence would suddenly tote a number of firearms up to a clock tower and gun down forty-three people. That man's name was Charles Wittman and he will be our next case study. 

Wittman's rampage took place in August of 1966 and dominated headlines. Why, everyone wanted to know, would someone seemingly so mild mannered and "normal" do something like this? (and it was later discovered that he'd killed his mother and wife prior to going to the clocktower). How could he do something like this? Wittman himself, it turned out, wanted answers too. In his suicide note, he wrote:

I do not really understand myself these days. I am supposed to be an average reasonable and intelligent young man. However, lately (I cannot recall when it began) I have been a victim of many unusual and irrational thoughts. 

 Some months prior, Wittman had written in his diary:
I talked to a doctor once for about two hours and tried to convey to him my fears that I felt overcome by overwhelming violent impulses. After one session I never saw the doctor again, and since then I have been fighting my mental turmoil alone, and seemingly to no avail. 

Whittman in his suicide note requested that an autopsy be performed on his brain. He got his wish. What the autopsy found was a brain tumour about the size of a nickel which impinged on or compressed three different key brain regions - the thalamus, the hypothalamus and amygdala. As you may recall from Neuroscience 101, these brain components are part of our limbic system and are at the core of many human and animal behaviours. The amygdala is especially pertinent here as it plays a major role in emotional regulation and governs such things as fear and aggression. As the amygdala is so important regarding human and animal behaviour, let's have a bit of a closer look at it. 





It's hard to overstate the importance of the amygdala in human and animal behaviour. All your "data input" through your five senses routes through this bit of hardware common to all in the animal kingdom. The amygdala "tastes" all this input for emotional content as well as attaching emotional content when this "data" is then shuttled around to other regions (including short term and long term memory). Any fears you have will be generated by this brain node, including all phobias. It will play a major role in not only your perception of fear and other emotions (from love to hate and everything in between) and how elevated that is but also how you respond and take action. When I wrote in an earlier post that there are subconscious systems that "drive your bus", the amygdala is a major driver with a great deal of "say" in how you interact with the outside world. 

Neuroscientist David Eagleman explains:

The role of the amygdala in human behaviour has been recognized as far back as the late 1800's when researchers discovered that damage to the amygdala caused emotional and social disturbances. In the 1930s, biologists Heinrich Kluver and Paul Bucy demonstrated that damage to the amygdala in monkeys led to a constellation of behavioural changes including lack of fear, blunting of emotion, and overreaction. Female monkeys with amygdala damage showed inappropriate maternal behaviour, often neglecting or physically abusing their infants. 

 Just a bit further on the limbic system and behaviour in general, it is known that far more messages from the limbic system travel up to the higher cortical regions than vise versa. In other words, the limbic system has far more "say" in what we do than our so called higher facilities located in the neocortex do. This is a huge part of what is meant by "subconscious" systems running the "conscious" you. These systems go awry and "you" go awry. 


Another Brain Tumour Case Study:

This is a case of something which strikes a strong emotional reaction in all of us - pedophilia. Is pedophilia the result of an "evil soul" or a "sick mind"? I ask that you not jump to conclusions here. Let's look at the case of a forty year man with no previous history of wayward sexual behaviour whom we'll call "Alex". Alex went from being a normally behaved married man to one whose sexual preferences suddenly changed. At the age of forty he developed an obsessive and overwhelming interest in child pornography and began to devote a great deal of time to it through magazines and web sites. He wrote later that he wanted to stop but just could not control himself. His behaviour progressed to the point beyond just pornography, he was discovered, charged and was convicted of child molestation. 

For some time prior to his imprisonment Alex complained of unbearable headaches and finally sought treatment. A brain scan revealed a massive tumour in his orbitofrontal cortex cortex. This is an area of the forebrain, or frontal lobes, known to be involved in sexual regulation among many other functions of judgement, decision making and planning. This is a more highly evolved bit of neuronal hardware that separates human sexual behaviour from that of our evolutionary cousins and fore-bearers. 

This handy bit of brain hardware is located here:





Things go awry here (or at least in a specific sub-region of this region) and sexual behaviour goes awry. It is this region of the brain that recognizes "sexual norms" (whatever they may be in your part of the world) and helps regulate your behaviour accordingly. 

And to further illustrate this point, once the brain tumour in Alex's orbitofrontal cortex was removed, his sexual behaviour returned to normal. And to present even more evidence, Alex's behaviour did take a turn for the worse again. But it was discovered that the surgeons had missed a part of the tumour and it had started to enlarge again. The remaining bit of tumour was removed and again, Alex returned to normal sexual behaviour. It was also a huge part of this brain region that was demolished when the tamping rod blew through Phineas Gage's frontal lobes, forever altering his behaviour. 

While this is but one case study, numerous studies and enough research has gone into the relation of this region and sexual behaviour and preferences to firmly establish that damage, underdevelopment or hyper-activation of this region will lead to sexually perverse behaviour (not to mention other psychopathic or sociopathic behaviour). There are also other ways that this important regulating part of the brain can be bypassed or compromised, not to mention how it was genetically and environmentally endowed in the first place, that we'll look at in future posts. 

So I hope those cases gave you some insight into the relation between brain regions and their functions and corresponding human behaviour. Simply put, damage or somehow alter the functioning of a given region and you alter the behaviour of a person.

Now does this mean I'm saying that brain damage or impaired neural development should absolve people of their anti-social or criminal behaviour? Why, as a matter of fact I am. Neuroscience is shining a vast amount of light into what we have traditionally regarded as "responsible" and "moral" behaviour. And unlike our past clumsy attempts at this, now we have have objective methods to examine and understand human behaviours rather than our traditional subjective (IE: opinionated and crudely judgmental) methods of the past. Understanding human behaviour through objective science means not only can we understand why people behave the way they do, but based on this scientific understanding we can better design methods to correct that behaviour that will be far superior to our ancient, crude and tragically ineffective and costly punitive methods. 

As I said in my opening post, I became far, far more compassionate towards my fellow humans when I began to understand how brains really work and that I thought, or hoped, you'd become the same. What I'm asking that you open your mind to is the fact that outwards behaviour that angers you is almost certainly to be the result of a brain problem and is not a "morality" problem or some sort of intentional act. This will take more to establish than just this one post but I want to set the stage for much of what's to come (though it won't all be just regarding moral behaviour). 

Now am I suggesting that we should just allow any anti-social behaviour and forgive it because their brains are broken? No, not in the least. What I'm suggesting is that when we look at a case of anti-social or criminal behaviour that we realize that simple traditional punishments are highly unlikely to "fix" that behaviour y and understand that there are better, more scientific methods for correcting that behaviour. This is not a matter of being a "bleeding heart liberal"; it's a matter of acting on the most up to date science, pure and simple, and getting better outcomes as a result. What we're learning about the brain and behaviours is as literally ground shaking as learning that the earth was not the centre of the universe and will have as profound an affect on the future of human relations and development. 

This is the direction various branches of neuroscience, philosophy and the studies of ethics are heading, all based on the ever emerging scientific understanding of what drives human behaviour and morality. 

"Now", you may very well be thinking, "but those were clear cases of brain damage. Surely not every pedophile (for example) has suffered brain damage?". And you'd be quite correct. We can't pin all wayward human behaviour on brain damage suffered through injury or disease. But as we go along, we'll see that a great number of factors can affect these different regions and thus the behaviour they're responsible for. Genetics play a large role but we'll see all kinds of environmental factors can have huge and profound affects on the development of these regions and how they perform, or not perform at all. 

While regional brain damage and/or developmental problems have been firmly established to affect specific behaviour, animal and human behaviour is not completely governed by "regionology" (my term), that is, it's not completely just damaged or over/underdeveloped brain regions that govern behaviour. Neurotransmitters play a very large role in lighting up certain regions and thus driving behaviour and the neurotransmitter dopamine is a real linchpin here. So dopamine, and its fascinating role in virtually all of our behaviours, will be examined next. 

Sources:

David Eagleman's Incognito: The Secret Lives of the Brain

Rita Carter's Mapping the Mind and The Human Brain Book

Daniel Dennett's Breaking the Spell

Neurobiologist Dean Buonomano's Brain Bugs: How the Brain's Flaws Shape Our Lives

Various works and thoughts of Patricia Churchland

Numerous, numerous science websites such as this one.

Thank you as always for reading along. 


Saturday, November 16, 2013

A Review and Some Other Thoughts





One of the beauties of presenting learning material in blog form is that blogs can be interactive and the presenter can adjust the presentation on the fly depending on that interaction. For instance, after the opening three posts of this blog I got some valuable feed back. One reader had some very good questions that gave me some valuable insight into how the material I'm presenting is being perceived and another reader felt that the “basics” in Neuroscience 101 were pretty advanced. So now I can adjust my “course” accordingly. In my opening post I said I was a good teacher and gave the reasons. 

Bearing in mind some of my feedback, it's probably a good idea to review some of the key points of the previous post before we go on.

Review:

The brain is made up of a few key components which we looked at in the previous post. Neuroscience doesn't refer to them as components but we'll use that term for now for simplicity's sake. I'll also refer to them as the “ABCs” of neuroscience, or in other words the basic building blocks of the common language we need if we are going to learn and discuss the brain and human behaviour. I said in my introductory post that there is much that is known about the brain and there is much yet to be discovered and understood. The following is of the known variety. This is all beyond any shadow of a doubt. The key components are:

  • Neurons (brain cells in common vernacular): We'll say for the time being that neurons encode information, or “data” as I'll refer to it. We'll examine in more detail what this data might be and how it gets to a neuron and how that data gets utilized or not. (that “or not” is no doubt the source of many of your frustrations – like when you're in an exam and can't remember a certain math formula that you were sure you knew or you can't recall the name of person who's standing in front of you and who you'd been introduced to many times and so on. We'll also examine how the brain organizes and accesses this data and what might “block access” to that data (often at the worst possible time)).

  • Wiring: wiring carries data between neurons (“local”), between the various brain regions, and between your brain and various parts of your body (“long distance”). Actually, we could break long distance down further by saying between brain regions would be like between states or provinces and between your brain and your body would be like “overseas” long distance. These are the axons and dendrites we looked at in Neuroscience 101 though axons do all the long distance work and dendrites are more just the receiving end of the wiring. Much fun detail on this to follow.

  • Individual brain regions: There are three major brain regions as you'll recall; the brain stem, the limbic region and the neocortex. These in turn subsist of highly specialized sub regions. The brain stem has the fewest and most basic, the limbic region has more and slightly more advanced regions and the neocortex is where all the highest and most advanced cognitive functions exist. It is homo sapians' highly evolved specialized regions in the neocortex that make us what we like to call “human”. The wiring (and perhaps other factors that we'll look into) is what connects all these regions and is how these regions work in concert (or not as we'll see).

  • Glia cells: These are the “new kids on the block”. Until quite recently they were thought to be just “filler”, kind of a scaffolding, the job of which was merely to hold neurons and their networks in place. That notion has been thoroughly thrown out the window (see how science works? New vital discoveries happen all the time) and it is now known that the various glia cells far outnumber neurons and furthermore they are an ultra critical component in how the brain functions. We'll be looking at some eye popping details about these little guys.

  • Electricity, neurochemicals and synapses: I'm going to lump these together for now but we'll see they are quite different things (though also sort of not). I put them together because they basically are how communication takes place between neurons, between the different brain regions and between the far flung regions of your body and specialized brain regions dedicated to those body regions.

  • Hormones: hormones are a powerful component, capable of shutting down essential brain regions at the snap of a finger, calling dormant regions into action within the blink of an eye, sending life saving messages to body parts and so on. They can save your butt or kill you (or otherwise get you into a lot of trouble you'd rather not have). We'll want to pay very special attention to how these work.

In our brain anatomy primer series we'll look at all these regions and components in a little more detail and learn more about what they do and how they're all cobbled together to make “you”. It is each our own individual arrangements of these six components and how they interact that is responsible for all of our behaviour (or the behaviour of any animal as we'll see when we look at basic brain structures and what they do).

How all these regions develop themselves and function depend on two other basic things; genetics and environment. Genetics are, basically, the DNA code you were born with. Environment is everything your five senses detect from the time you were in the womb. As you have zero control over the former and next to zero control over the latter, you kind of have had next to zero control over who you currently are. I qualified that statement with “currently” so that you'd not lose hope that you have at least a smattering of input into your “destiny” (1). Trust me, you'll be very interested in the amount of “control” you do have so you're going to want to pay rapt attention as we go along. Knowing what you cannot or potentially (much emphasis on potentially) can control will save you and others a lot of grief, frustration and wasted time and energy. I'll be sure to let you know when we get to those points so that you can stop snoozing, sit up straight, sharpen your pencil and take some notes (no, as much as you'd like to know these things now we're not ready to get to those just yet. Trust me, it would do you little good if you didn't understand how the ABCs work).

Who “you” are or who any individual is – for better or worse – is sort of a “more than the sum of the parts” of how those basic components came to form and function (as dictated by genetics (nature) and environment (nurture). Yes, there is something to the nature versus nurture debate after all. While the debate still rages, we'll see that neuroscience is providing all the answers once and for all. All the six components I listed operate autonomously, quite beyond your “conscious” control (and we'll see why this is a Good Thing. We'll also see why this can sometimes be a Bad Thing). These are parts of the “zombie programs” as neuroscientist David Eagleman calls them. Also, as we go into more detail about these autonomous systems, we'll understand what “subconscious” currently means. Neuroscience has a different way of looking at it than did the pioneers who first discovered the concept and gave it that name (Freud, et al).

ALL human behaviour originates in how these brain regions were formed and function together (or not function together). This will be very exciting so be sure to put on your Sherlock Holmes outfit. There'll be many mysteries solved here.

The human brain (or any brain for that matter) did not just pop out of the oven as is. It evolved to be what it is (and is of course still evolving. It's not like there's an “end point” to evolution. Well, that's not true either. The sun will burn out in a few billion years and that will be the end of that (unless we master inter-galactic travel and living by then)), a process that took billions of years and a lot of what we'll call “trial and error”. Knowing this, it is impossible to learn and discuss neuroscience without delving into evolutionary biology and the various disciplines of evolutionary science. Human behaviour, the brain, and evolution are so tightly wound together that is it literally not possible to understand “us” without examining the three all together almost as a single entity. So yes, I'll be weaving the facts of evolution into our look into our Inner Galaxies. No worries! It'll be fun! (no drab, dry lessons in my classroom)

Again, I said that some things about the brain were known and some not so much. Everything I've listed and told you here is very – and I do mean very – on the known side of the ledger. Yes, I know how distressing it is to learn that you have next to no control over who you are and what you'll do in life but … well, hang on.

The big question in neuroscience (and philosophy) are the twin notions of “free will” and “consciousness”. These are on the not completely known (or agreed upon) side of the ledger. What is known and quite widely agreed upon by the top neuroscientists and related philosophers (we'll see that there's actually quite a bit of crossover) the world over is that if either exist (and many firmly assert that neither do and not, as we'll see, without very solid evidence), it's not very much. We'll see that the “conscious you” - the you that opens your eyes and “sees” the world and experiences “thought” - is more or less a passenger (or perhaps the captain) on a very large biological ship (IE: your brain) that navigates through what will be your time on planet earth. Hey, I did warn you that this trip through your inner galaxies would at times be scary (and by scary I mean disturbing and distressing). But don't worry, there's an “app” in your brain to deal with that (which has already been put on alert and spun into action without you needing to give it any direction. We'll be looking into what we sometimes call “bullshit detectors” in fascinating detail and why, if yours is firing now, it's wrong. It's often wrong so don't worry. At any rate, it'll help deal with any distress you're experiencing). Like you, I believed in “free will” and consciousness and soul but once I understood how a brain works and what's understood about brains, I could see that my previously held notions had nary a leg to stand on. So I get how you feel.

I also touched briefly on “reality”. It is necessary to tie this concept into free will and consciousness. It is also extremely well studied, understood and agreed upon by neuroscience that your unique brain (remember, there's only one like it; not only on the current planet, but in the history of the planet) constructs everything that you perceive as “real”. By real, I don't mean whether a tree is a tree or a rock is rock and all that other nonsense that people get into splitting-of-hairs debates about. We can measure those things with instruments and objectively agree on what they are. However, reality as you perceive it is a very fuzzy concept but about which we must all understand more. So, as your brain is the only one like it in history, your “reality” will be the only one like it in history. Cool, eh?! But here's the fly in the ointment – it's all of these individual homo sapians' different realities that give rise to all human conflict. So, as you can well imagine, it's kind of important that we understand this concept. But don't worry, there are ways we can get our realities to converge more and, as we'll see, how they at times spontaneously converge (a very cool concept known as “collective consciousness”). 

I need, before we go too much further on in our series of lessons, to further establish and defend my position that neuroscience is the best tool we have for understanding human behaviour but I am approaching my word limit for a single post and I can see your attention span is wavering for now.

Again though, this is the beauty of blogs. We don't have to tackle too much at once. We can take them in bite size pieces one or two times a week. And yes, I know, some of you will be swallowing these bites easier and for some these bites are going to require quite a bit of chewing. For the latter, it'll all be worth it, I can assure you (but don't worry, if you let it, your brain itself will do most of the chewing for you without “you” having to do anything! Just wait until you learn how this works!).


(1) – the whole concept of “destiny” is one we're going to thoroughly turn on its head. For now, just know that everything you've likely learned about this concept (unless you're already highly advanced in neuroscience or related philosophies) is all rubbish, the stuff of past mythology, and needs to be set to the curb (or kerb depending on where in the English speaking world you live). Yes, I understand how dear these myths likely are to you and to whatever culture you reside in, but trust me, you'll thank me for this. It's all part of understanding “human nature” and reducing our conflicts so this will be highly worth it as well. 

Sources:




Various Daniel Dennett and Richard Dawkins over the years

My circle of dear neuroscientist friends on Google Plus and Facebook who ever so kindly hear my questions and either direct me to various sources or answer my questions outright and who constantly stimulate my mind

Various neuroscience research papers too many to mention

Sunday, November 10, 2013

Neuroscience 101

Neuroscience 101:


    This will be a very basic primer into the physiological systems that makes a brain - IE: "you" - tick. It will seem quite lengthy, for which I apologize, but there is a lot to get to. Human behaviour is, as I briefly demonstrated in the previous post, extremely varied and complex, not to mention seemingly incomprehensible, and if we are to begin better understanding our complex selves - or even our simple selves - it is basic brain functions as understood by current neuroscience that we need to better understand and be aware of. It is my hope that this post - and following posts that will explore these basics in more detail - will serve as a) a reference for us to refer back to as we go along, b) a reference for your future use and more importantly, c) an impetus and inspiration for further curiosity and reading on your part (if not, I will be doing my best to provide as comprehensive an understanding as possible in the easiest way for us layman to utilize). 

    So here we go, let's dive in.


     First of all, you have in the neighbourhood of one hundred billion of these:


    That's a neuron and according to renowned neuroscientist David Eagleman, each one - all one hundred billion of 'em - is as complicated as a major city (there's an astonishing level of activity that happens in all of your cells, it's just that brain cells take that to a new level). Neurons "encode" stuff. The details of all your thoughts, memories and all your knowledge are encoded in various neurons (for example, there's a "Jennifer Aniston neuron". Honest! The discovery of this is detailed in neuroscientist Sebastian Sueng's book, The Connectome. Whether you have a "Jen neuron" or not depends, of course, on whether you've seen her or not and whether a certain other brain region has "decided" if this person is important to you or not). They pass that encoded stuff (to assemble bigger pictures or ideas or memories) along to other neurons via these:


    Those are axons (sending) and dendrites (receiving), AKA "the wiring" (though technically more the former than the latter). While brain cells are more or less permanent, the wiring is not. (By the way, contrary to popular belief, you do not "lose" brain cells ... no, not even after a bad bender, but yes, it can feel like that. And we're going to look in much detail at what happens when you abuse that poor brain of yours by consuming various substances, or "food" for that matter, and why it "feels" like we lose brain cells. It won't be pretty). Axons, dendrites and synaptic connections grow and "prune back" all the time, creating new connections (and thus memories, learned behaviour and the such) or trimming them back (if a certain memory function falls into disuse for example). As you can see by the number of dendrites, there are many, many connections between neurons (as many as ten thousand according to some counts!). Dendrites and these multiple, multiple connections are a big part of our mental puzzle. A more realistic depiction of what these connections look like appears like this:






    That bright green blob in the centre of the image is a neuron. Yup, you've got one hundred billion of those, each one with enough activity within it to be compared to a major city. Imagine the activity of one hundred billion cities going on in your brain (though not exactly all at once - more later). 

    Communication between neurons is sent along the axons in electrical pulses not unlike Morse code. At the point of connection between an axon and a dendrite we have a synapse and at this point the electrical pulse triggers the release of a neurochemical which will pass the message from axon to dendrite and thus onto the next neuron. The details of this transfer, and the synapse itself, look something like this:


    This happens to be for the system involving the neurotransmitter dopamine. You may notice opiate receptors as well, along with endorphins. We'll be coming back to opiates and the brain later. As you can see, there's a lot going on there. There are receptors, "uptake pumps", there's a system - not shown - for whisking away excess neurotransmitter material and so on. This operates on a ridiculously delicate balance (we're going to come back and examine this in more detail in a future post). There are something like one hundred known neurotransmitters, all of which perform inter-neuron communication in various regions of the brain and all of which are responsible for various functions that drive "you". Look again at that tiny detail (and you may recall that it was a description of the function of a synaptic connection that first drew me into neuroscience). Much of who you are and what you do depends on that infinitesimally small chemical transaction. Now get this; your brain has somewhere around one hundred and fifty trillion synaptic connections at any one time all performing those little chemical transactions. And to put that number in perspective, in just a few cubic centimeters of cortical tissue you have more synaptic connections than there are stars in the Milky Way (David Eagleman's Incognito). Now stop reading. Stop and really imagine - again imagine those hundred billion cities between your ears. Now imagine enough transportation connections between them that the numbers dwarf several major galaxies. Yeah, I know, pretty awe inspiring. And quite beyond the capacity of the imagination of most of us. 

    The dopamine system and pathways happen to be one of the most studied and well understood. The dopamine pathway looks roughly (and I do mean roughly) like this:


    As you can see, the seat of our emotions, a small part of the brain called the amygdala, is included in the loop. And hey-ho, what's this? Our "planning and judgement" centre is a destination? Yuppers. A lot of what you "think" is "good planning and judgement" may well be just your primitive brain reward system sending an emotion generated "good feeling" message to your "command centre". And this diagram just represents the dopamine pathway. Remember, there are over a hundred different neurotransmitters at work throughout your brain all governing - way below your conscious control - various functions going on in all those billions of cities in your brain. 

    Let's return to the "wiring". There's "local" and "long distance" wiring. Local wiring in the mammalian neocortex looks something like this (and this is a greatly simplified drawing). It works in layers and each layer performs a slightly different level of function (from Sebastian Seung's The Connectome). 



    Long distance wiring is longer axons that form "bundles". This wiring connects the different brain regions. It is believed by some neuroscientists, such as Sebastian Seung (linked to above), that it is the unique wiring we each have between our brain regions - or "connectome" - that is responsible for much of "who we are". A basic "wiring harness" looks something like this:



    The brain and its wiring is not, as once thought, "set" once full neurological adulthood is reached (about age 25). As mentioned, axons and dendrites grow and prune back depending on the demands, or lack of them, put on a region at any one time. This falls under the general heading of neuroplasticity, a term that describes the malleability and changeability of our finest (and we're talking very fine) and even major brain structures. We'll come back to this important concept in much more detail in future posts but right now it's important to know that this plasticity can be good (the brain changing to adapt to a major change such as blindness) or bad (adapting to a harmful behaviour or practice (brought on usually through negative experiences or environmental conditions)). And that wiring? You have, in that small space between your ears, enough wiring to wrap around the world - twice. 

    But the wiring does not end there. The wiring includes the central nervous system and connects every square centimeter of your body to your brain, something like this:



and this:






    These are not only to send messages to muscles to move and to receive information in return or to receive and send pain signals (and we'll learn that this is a two way street) but are also part of a "full systems" monitoring program that is constantly testing what's going on in, as the latter diagram shows, your major organs. We'll be examining this in more detail as well when we learn more about the mind-body connection and how, for example, what goes on in your stomach may affect your mental health. For that matter, what goes on anywhere in your body is going to affect your brain in some way.

    Aside from neurotransmitters, there are also hormones involved, such as the stress hormone cortisol. Its pathway looks something like this:


    The stress response system is based on our primitive brain "fight or flight" response to perceived danger (and the term "perceived" is very pertinent here. How we perceive danger is one of the things that gets out of wack in our brains outside of our conscious control. Phobias fall under this category, among many others). This system is essential to our survival and we'll explore this crucial system in more detail later but what's important to understand now is that this system evolved for fairly simple dangers like a saber-toothed tiger eyeing you for dinner. In our modern wacky world the concept of "danger" and our response to that is way, way more complicated and this system is often put under extreme duress. We'll be returning to this a LOT as we try to understand this system's effect on our behaviour and physical and mental health.

    There are of course numerous hormones that greatly influence our behaviours and "who we are". Some are quite familiar to most of you - testosterone and estrogen for example - but we'll look at others as well and more importantly look at better understanding the roles these play in what we do and why we do them (or not do certain things). 

     And in among all those neurons and wiring are glia cells. Neuroscience is just scratching the surface of the essential roles these play. One critical role is in supporting the growth of the myelin sheath, a protective coating on axons (the breakdown of myelin is thought to play a role in MS). As well, they are involved in supplying nutrients and oxygen to neurons along with various "clean up" duties. Recent research suggests that among the reasons we need to sleep is that glia cells need the brain to be in a resting state for them to perform many of their functions (most critically, it appears, the essential house cleaning duties they perform). Glia cells look something like this:



    Isn't this just the funnest stuff?! I love this stuff! Let's carry on. 

    Reptile brains, then higher brains followed by the mammalian brain, then the early hominid brains and finally the modern human brain evolved over millions of years. Each was basically bootstrapped off of the more crude and ancient reptilian brain. (Yes, I know how sophisticated you think you are, but at your core you are exactly the same as your average frog.) The limbic system evolved next and then, as mammals came on the scene, the neocortex evolved (or mammals came on the scene as the neocortex evolved I suppose). Thus our basic brain outline looks like this:


    That big reptilian brain blob at the back of the brain is the cerebellum. That's where body movements are coordinated, where your abilities of balance and body posture are held and equilibrium is controlled (yup, the most graceful ballet dancer or gymnast in the world shares the basic hardware responsible for what they do with a lizard). If you're not super graceful, blame this region, not yourself. The limbic system is where a number of major control centres reside, including, but not limited to, the aforementioned amygdala, the hypothalamus (the control centre for many autonomic functions), the hippocampus (involved in memory forming, organization and storing) and the basal ganglia (or basal nuclei; involved with a variety of functions, including voluntary motor control, procedural learning related to routine behaviours or "habits" such as bruxism, eye movements, cognitive and emotional functions).

    Finally, we have the neocortex. This is divided into major regions that look something like this:



    If you'd like to know where "you" are - the seat of human consciousness and awareness - that's in the frontal lobe. We'll have much fun examining how much - or how little, perhaps I should say - that part runs your life. And do you see that part called the occipital lobe? That's where you "see". Our eyes merely collect light. That live action movie that takes place when you open your eyes gets produced, edited (yes, whatever you may think, a lot of editing takes place of what your eyes take in) and assembled in your occipital lobe and which then presents the final cut to "you". 

    The neocortex is where the responsibilities of our higher functions lie. The neocortex is divided into a dizzying array of specialized functions. This is a short list but all areas of thought and cognitive functions will have a corresponding brain region that looks roughly (and again, I do mean roughly) like this:


    These represent just a small handful of examples and are only roughly located in this diagram as the areas are presently understood (neuroscience is making new discoveries all the time so none of the exact specifics of these locations are set in stone but the basics are well understood and agreed upon). How "good" you are at any particular activity will basically depend on a) how well developed a particular region is (say the Brodmann and Wernicke areas of language, for example (roughly "speech production" on the chart) or something more rudimentary like your cerebellum as we saw), b) how well the wiring is developed between your regions and c) how your particular neurochemical pathways perform. It's somewhat more complicated than this but these three are well understood to be the basic components. I earlier compared a graceful ballet dancer or gymnast to a lizard. It is in the neocortex where we can find the answers as to why the former can take the same basic muscle-skeletal system and brain component - the cerebellum - and perform quite a bit more complex body movements with them. Or why any mammal can physically outperform a lizard for that matter. There are of course some physical differences between, for example, a chimp and a gecko, but most of the reasons involve the differences in brain structures between them, the most important being that a chimp has a neocortex and the lizard does not. That you have the most evolved neocortex on the planet is also why you're more sophisticated - most of the time we'd hope - than a frog (to which I also compared you). But, well, we'll see. When we really start comparing you to a frog (or any of the other creatures with which we share basic brain hardware and functions) you're going to find it quite humbling. 

    That our brain regions and the connections between them are all different puts a whole new meaning on "smart" or "talented". "Smart" or "talented" is just a blessing of various regions being better proportioned and wired for a given task and you accidentally discovering the use of these regions (or more likely having them discovered for you). If you're a math "genius" and make a living from that, for example, you can climb down off your high horse and thank your lucky stars that you were gifted (and we'll see what "gifted" really means ... nothing to do with "you" I can assure you) with highly developed regions specific to math tasks (nature) and that they were discovered and developed (nurture, which strengthens the connections, or wiring, between these regions and the rest of your brain). Many people may be similarly gifted but tragically never discover these gifts (and we'll see that undiscovered geniuses may be at this very moment living in the slums, for just one example, of Lagos, Nigeria). Others may not be so gifted but are cursed with high desire (or being driven by well meaning but ill-advised parents) and thus tragically beat their heads against the wall (and beat up on themselves) trying to do something they were simply not endowed to do.

    All of this, the billions of neurons, the trillions of synapses, the dozens and dozens of specific brain regions, the hundreds of thousands of kilometres of wiring that tie it all together and the more than one hundred neurotransmitters, hormones and proteins that make it all communicate, harmonize to make up this - your brain:



   The brain from any healthy adult will look like the one pictured above but here's something to consider, and is the essential foundation to what we will learn about brains - no two brains are alike. They are as unique as fingerprints. All those regions are connected slightly differently between us as well as some regions being better developed or activated and some not so much (which can be long term or short term), the wiring is slightly different between us and so on. This is, as I've pointed out, determined by genetics and environmental factors, with a strong emphasis on environmental factors. Even identical twins (of which I am one) who start out genetically identical will develop quite different brains (as a twin myself, and because twin studies are so fascinating, we'll be returning to twin studies quite often).

    The brain collects "data" through the five senses (sight, sound, taste, touch and smell), runs this data through various brain regions and creates the "reality" we perceive in our minds. Because our sensory organs and brains are all genetically different (with the exception of twins) plus are wired and developed slightly differently, we will all have different "versions" of "reality". This is why we find it hard to agree even when we're both looking at the exact same thing (like two people seeing a spider for example. One may look on with fascination and curiosity, the other will have a phobic melt down).




    This is going to be a critical part of our examination of human nature and the brain. Remember how I said we needed to better understand brains if we as people were going to better learn to co-exist and cooperate with each other? Obviously our differing views of realities - and we have very, very little conscious input into what these are (or exercise very little as we'll see) - are major sticking points. "Reality" is one of the great philosophical questions of all time and, as it turns out, crucial to understanding the human brain and our inward and outward "selves" and, most importantly, how all our widely varying "selves" get along with other "selves". It is, as the Chinese say, quite "複雜 " (complex). We'll be examining this a lot and how we might better agree on "reality" (hint - science).

    All this stuff is what's "under the hood" of our skulls. And this three pound collection of cells and wiring is, as any neuroscientist will tell you, the most complicated device in the known universe. When human behaviour goes wrong, there's something wrong - emphasis on something - "in there" ::waves a hand in the direction of all the diagrams outlining the ridiculously complex human brain::.  All that varying behaviour we looked at in the previous post can all be explained by understanding all that ::again waves a hand at all the brain basics we just looked at:: That's it - nothing mythical, nothing otherworldly, just how all those things are arranged in each of us. And here's the kicker; even neuroscientists will admit they don't understand the brain very well. And they don't. Neuroscience, like astronomy (and they aren't that different in terms of vastness and complexity), is very much a work in progress. We can study deceased human brains, but it's exceedingly difficult to study live human brains with instruments. This is why so much neuroscientific study takes place on animal brains (many systems are similar between us and animals, remember, so discoveries on mammal brains can be to some degree extrapolated up to the human level. Even neuron and axon structure on something as simple as a round worm are essentially the same as ours (and so form a basis for neuroscientific study). Human psychology is far more complex however (and this will entail a great deal of our exploration). Advanced neuroimaging technology is helping to a large degree in our study of brains and individual personalities and characteristics contained within them (and there's the technology that can even probe an individual neuron and detect that it only activates when presented with an image of Jennifer Aniston (as one example) and thus the "Jen neuron"). While great advancements have been made on the details (as exemplified by those breathtaking diagrams of neurons and synapses), how it all comes together and creates a "you" remains at least somewhat mysterious (or a lot mysterious, depending on one's confidence in today's theories and knowledge (knowledge that is changing all the time)). 

    And here's the big take away for today. All of that "stuff" runs a mind boggling number of subconscious "programs", what Eagleman calls "zombie programs" and it's your particular collection of zombie programs (we all vary in these though some are quite standard) that run "you". No, "you" don't run "you", all these automated zombie programs - programs that run through all those neurons, wiring via electrical pulses, neurochemicals and hormones (to put it very basically) - run "you". Zombie programs are all your daily routines that you don't need to think about in addition to all kinds of other little programs that push you forward through life. All those "conscious decisions" you make are almost certainly to be the result of various zombie programs spitting out, for example, the "decision" to buy a new car (which is just a glorified modern variation on ancient hunter-gatherer instincts) or take a new night class or pick a certain supermarket product over the others and so on. Then your dopamine reward centre gives you a "hit" of happy feeling dopamine to "reward" and "re-enforce" this behaviour. These are going to be a huge part of our exploration of what makes humans tick (or even your cat or dog if you like!).


    Phew! Wasn't that fun?! And that was just the very basics. In future posts we'll look at all these parts in more detail. We could think of all these parts as pieces of a puzzle that we are putting together. The completed puzzle is a biological computer of such dazzling complexity that human language is inadequate to completely describe it. For every second of every moment you are alive, your biological computer - your brain - will be performing an astounding number of functions, virtually all of which are outside of your conscious awareness, let alone control. In fact, as I've already alluded, we will see how astonishingly little control we have over who we are and what we do (though once we understand why that is it'll be far less astonishing and the only way we could possibly operate and get through life). 

    But perhaps more importantly, we'll learn more about just what kind of control we do have. And isn't that something we'd all like to know more about? But more than that, the answers to all the questions we looked at in the previous post can be found by better understanding how these amazing biological computers of ours operate.

Oh, and I hope you now better understand the meaning of "inner galaxies" in the title of this blog - you truly do have vast inner galaxies in your brain. Now is that cool or what.