brain control

Hi, I’m Iman Kiani. In this lecture, I wanna talk about the behavioral and motivational mechanisms of the brain. First I’m
going to introduce two historical stories, which somehow changed the way we look at ourselves, at our brain, then I’ll talk
about Kluver-Bucy syndrome, as a motivational mechanism we know, for now, and then I’ll explain an experiment on free
will, which we don’t know, for now, whether it exists or not.
1- Gage’s case
You’ve probably heard of him. Phineas P. Gage was an American railroad construction foreman. He’s famous because had
an accident in which a large iron rod was driven completely through his head, destroying his left prefrontal lobe. He survived
the accident, but the intriguing point was that Gage’s character completely changed after that, in a way his friends stated
he’s no longer the Gage we knew. He became another person. They’re different people. The colleagues described the preaccident Gage as hard-working, responsible, "a great favorite" with the men in his charge, and his employers having
regarded him as "the most efficient and capable foreman in their employ". After the accident, he got irreverent, indulging
at times in the grossest profanity, impatient of restraint or advice when it conflicted with his desires. This is what the
psychiatrists noted about him at that time.
We can say He was the first case where you could say fairly definitely that injury to the brain produced some kind of change
in personality.
Unrelated to the topic, I think it’s worth mentioning. As I said, Gage’s friends stated that he has become another person,
pre-accident Gage and post-accident Gage are different people. Researchers made a creative survey, they gave people two
scenarios. In the first one, after the accident, the person shifts from positive characteristics to negative ones, like Gage’s
case, but in the second one, the person shifts from negative ones to positive ones. In the first scenario, people believed the
person before the accident and the person after the accident are different people, they’re not the same, but in the second
one, they believed they’re the same people, and he’s improved, he’s got better, but he’s the same with the one before
accident, they’re not different people.
Getting back to the topic, this accident, Gage’s case, like the next one I’m gonna talk about, changed the paradigm of
neuroscience. They showed that maybe the brain itself forms the superego, as Freud calls it, not a supernatural spirit.
2- Antidepressant drugs
Since the 20th or 19th century, as you know, scientists have been looking for new chemical drugs for different diseases,
including schizophrenia. As you know, people with schizophrenia have symptoms like hallucinations and delusion, and some
of them have depression as well. People suffering from this disease are usually kept in psychiatry hospitals, and researchers
test new drugs on them. In about the 1950s, some scientists like Muller saw that some of the drugs they test can affect this
depression, sometimes curing it, while they didn’t even think that depression can be treated chemically.
As I said, these happenings somehow showed that our feelings may be managed by the brain, by the material, and this was
quite inspiring for the next studies. Studies which showed how our brain controls our feelings, like fear, which I’ll talk about
in the next slide.
3- Kluver-Bucy syndrome
This syndrome results from bilateral ablation of the amygdala. We have two almond-shaped clusters of nuclei located deep
and medially within the temporal lobes of the brain, which we call the amygdala.
This syndrome has 5 main signs, which include: hyperorality, hyperphagia, hypersexuality, hypermetamorphosis, and
docility. In this picture, we can see docility. The monkey is supposed to be scared of the snake, but here it shows no sense
of fear. Now we know the amygdala as the fear center of the brain, so when it’s damaged, the person won’t feel scared. To
prove that this docility is not specific to animals, here we can see drawings made by a person whose amygdala had been
damaged, the doctor asked her to draw a face related to the feeling, and as you can see she didn’t know what an afraid face
would look like, or when she was asked to rate the emotional content of a series of facial expressions, she failed to recognize
fear.
Although there are other structures related to the sense of fear as well, like the hypothalamus, the main center is the
amygdala. The amygdala has other functions as well, for example, hypersexuality is another sign of the syndrome. It means
that the animal may mate another animal with the same gender or even of another species, for example, a cat with a dog,
it’s what we call hypersexuality. So, it looks like, although it’s small, it has some major roles in our behaviors.
4- Free will
One of the most interesting parts of neuroscience for me is free will. I took it as an example of something we don’t know of
brain. Many experiments have been conducted on this, one of the most famous ones is Libet’s experiment. In Libet’s
experiments, participants were asked to perform a simple task such as pressing a button or flexing their wrist. Sitting in
front of a timer, they were asked to note the moment at which they were consciously aware of the decision to move, while
EEG electrodes attached to their head monitored their brain activity.
Libet showed that there was unconscious brain activity associated with the action for an average of half a second before
the participants were aware of the decision to move, a change in EEG signals that Libet called “readiness potential”. This
experiment appears to offer evidence that decisions are first made by the brain, and there is a delay before we become
conscious of them. we attribute the action to that conscious feeling, while the actual decision was made unconsciously. In
this picture, you can see how the experiment’s been conducted, with the EEG and the clock, and the button.
However, the experiment is strongly biased, I’ll list two of the biases. Firstly, asking the participants to note the moment at
which they were consciously aware of the decision to move doesn’t seem very accurate. Because it’s an ambiguous feeling
and we can’t note the exact time of making the decision, and secondly, the waves can be a result of subjects paying attention
to the experiment, not necessarily the so-called readiness potential.
But still, in spite of these biases, it remains an inspiring work to the next scientists.
5- What are we?
So, to sum up, we started with Gage’s case and how the antidepressant drugs emerged, and how these two showed what
the brain is capable of doing, then we talked about the amygdala and its functions as an example of neural motivational
mechanisms, and eventually, we went to free will, something we still don’t have enough data about.
I want to finish my lecture with this question, this fundamental question, that we should be looking for, that are we just the
material, or do we have something beyond it, the so-called spirit. It’s clear that many things, which we used to justify by
means of a supernatural spirit, can now be justified by brain activity. However, it’s not the first time it’s happening. For
hundreds of years, people used to believe the gods turn the stars until we found the gravity law.
However, I guess, comparing neuroscience to physics, we’re still in the dark age, not even Newton’s age. And after that
we’re gonna have Einstein’s, and we have a long path to reach there, so for now, we should probably wait, to see what will
come up in the future.