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. 


3 comments:

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