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Affective Neuroscience

January 11, 2011

Featured Content, Neuroscience, Psychology

Affective neuroscience – that does sound fancy doesn’t it? This is the name for the combination of neuroscience and the psychological study of mood, emotions and personality. Today, however, we’re only going to discuss the emotion part of affective neuroscience.

Last week we discussed life without emotion, much like in Brave New World by Aldous Huxley. There was a lively discussion and people asked some really good questions. Hopefully I will be able to shed some light on the whole topic by explaining (more) in depth how emotion is produced within our brains. Then, I will discuss the nature vs. nurture debate of emotion.

The Limbic System

Pierre Paul Broca, a physician and anatomist mainly known for his research on “Broca’s area” (one of the most important brain areas for speech production), is one of the scientists that suggested that emotion is related to an area in our brain called the “limbic system”. This system is a structure of multiple parts of the brain.

Research has shown that the limbic system indeed is directly linked to emotion, but that there are other parts of the brain that have (an even greater) influence on emotion as well. However, emotion is not the only function of the limbic system – it also plays a major role in long term memory, olfaction (smell), learning, behavior and special navigation.

Look at the following image to get an idea where the limbic system is located within your brain:

And now, look at this one (those with a weak stomache, don’t look :p ). This is what a real brain looks like, not at all like the digital image. It’s a lot less easy to distinguish the numerous different areas within a real brain.

As for what the different parts of the limbic system do:

Amygdala – this part of the limbic system recognizes emotions through visual and auditory input, but is mainly focused on negative emotion, primarily fear.

Cingulate gyrus – plays an important role in regulating functions such as heart rate and blood pressure (much like the hypothalamus), but also in cognitive and attentional processing.

Hippocampus – the hippocampus is important for the formation and storage of long-term memories. It also plays an important role in spatial memory and navigation.

Hypothalamus – The hypothalamus is mainly a regulator: it regulates blood pressure and heart rate, hunger, thirst, sexual arousal and the sleep/wake cycle.

Olfactory bulb – a very important organ for the perception of odor.

Thalamus – this is the “relay station” of the brain. The thalamus receives sensory input, and distributes it to the associated areas of the brain (with exception of the olfactory system, see the olfactory bulb).

There are other areas that have been and are associated with the limbic system, but these are generally agreed on, and are the most important.

You’ll remember last week’s blogpost where I discussed the James-Lange theory, where the suggestion was that bodily reactions cause emotion – the hypothalamus (and the cingulate gyrus) would play an important role in that one.

Nature vs. Nurture

Something I wondered about after reading some of the comments on last week’s blog, was whether our emotions are something that we are born with, or something that we learn over time. My question: are emotions something that we learn through cultural norms?

Perhaps you’re familiar with the “nature vs. nurture” debate. This is an ongoing debate between many psychologists. They are trying to find out whether we are born as the “tabula rasa” (“blank slate”, originally a philosophy of John Locke – the idea that knowledge comes from experience and perception) or if most of our personality and knowledge is built out of hereditary (genetic) information.

Through cross-cultural studies researchers have found that people in (e.g.) Indonesia and in America experience the same feelings and physiological changes when they make facial expressions of fear, anger, sadness and disgust. The researchers suggested that the physiological changes with emotion are genetically (rather than culturally) determined. This would mean emotion and the associated bodily changes are of “nature” instead of “nurture”. What is also interesting is that the faces people make when expressing an emotion are cross-culturally identical as well.

However, this study also suggested that culture strongly influences whether and how people talk and show their emotions and what produces them. In Japan, for instance, it’s not done to show or discuss sadness or disgust, whereas in western countries it is less frowned upon. Also, in countries such as China, Thailand and Colombia, it is fairly normal to eat insects (both for nutritional value and taste), whereas most Europeans and Northern Americans would feel disgusted only at the thought.

I hope I have been able to shed a little light on the questions that came up last week! If you still have questions, please feel free to ask and I will do my best to answer them!

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About Manon Eileen

Dutch 23-year-old SF/F YA writer, BSc in Psychology and soon MA in Global Criminology. She is creative, easily bored, and craves tea all the time. Also: "science isn't about why, it's about why not" - Cave Johnson.

View all posts by Manon Eileen →
  • http://unsanityfiles.com Albert Berg

    Well of course Broca studied that part of the brain. If I had an area of the brain named Berg’s area I’d study it too. :)
    But in all seriousness, I’ve given the phenomenon of cultural norms a lot of thought in my time. For instance I believe many Americans would be unsettled at the thought of eating goat, when we have almost zero compunctions about eating cow. Another biggie for me for a long time was the fact that it was culturally unacceptable for a man to carry a bag of any kind because the “purse” is exclusively a feminine accessory in our culture. There’s nothing inherently feminine about a bag, but woe be to you if you if you’re a man an you need a little extra space to store your lock pick set and you’ve run out of pockets. Luckily I recently discovered cargo pants, and I no longer have this problem.
    But the point is, social systems in general tend not to be very objective. It’s almost as if totally random rules are a inevitable byproduct of human society. I wonder if that fact in and of itself is a result of some weirdness of the brain, or if it belies something far stranger.

    • Manon Eileen

      Hey Albert, thanks for reading and commenting again :) !

      You have really good example with the men/purse thing.

      I actually think social systems form over years of time. I bet that in times (long past, I suppose) it was normal for men to wear a bag. That’s changed over time. Same thing for what people think is normal to eat – it changes over time, and perhaps a lot of time.

      But I do agree social systems most certainly are not objective.

  • http://cmstewartwrite.wordpress.com/ CMStewart

    In college I learned that babies are born with 3 instincts- looking, grasping, and nursing- and all adult behavior can be traced back to the consequences of these 3 activities. So similarly, I think that babies have an innate general positive emotional response to positive stimuli (such as a full stomach) and a general negative emotional response to negative stimuli (such as an empty stomach). I would conclude all adult emotions can be traced back to these 2 diametric general emotions.

    • Manon Eileen

      Thanks for reading and for your reply!

      Your comment actually differs quite much to the others I’ve received, which is interesting. Are you a parent? Because the other people are quite convinced that their children had emotions right after they were born.

      Interesting.

      I too learned that babies were born with those 3 urges/instincts. Perhaps it’s the scientific way of looking at things, plus, that’s what they are *sure* of. I suppose whether or not babies have a personality/emotions when they are born is very hard to research.

      • http://cmstewartwrite.wordpress.com/ CMStewart

        I don’t doubt that babies experience general positive emotion and general negative emotion at birth. I just don’t believe a fully developed, complex personality is present at birth. What does exist, however, is the *potential* development of a fully developed complex personality.

        Not a parent to humans. :) l But I joke about being a “mommy” to my 2 cats that I’ve had since they were wee kittens. They are from the same litter, and almost the exact opposite in personality. One is very people-oriented, very vocal, and loves to be picked up and held. The other is very reclusive, very quiet, and struggles and scratches when picked up. My husband and I love them both equally and have spent the same amount of time petting and sweet-talking one as the other. Now I don’t know how much of a comparison we can make between a cat brain and a human brain, but for the sake of argument, let’s say the innate instincts and innate positive / negative general emotional responses are roughly similar. I would attribute the extreme differences in their personalities to differences in their environments- the way they were treated by people and other cats while they where still nursing (we got them after they were weaned). I’d also attribute the differences to minute yet pervasive differences in their brain structures. (It’s important to note that “brain structure” does not mean “personality.” One is tangible and the other is intangible.) Just as our 2 cats don’t look exactly alike, I’m sure their brains aren’t formed exactly alike. They aren’t genetic replicas of each other. These physical brain differences are what makes one cat pre-disposed to one reaction, and the other cat predisposed to another. So 2 slightly different brains exposed to 2 slightly different environments will, through exponential increase, produce 2 very different personalities. Without any kind of stimulus, a brain will not produce a complex personality.

  • http://petersaintclair.wordpress.com Peter Saint-Clair

    It is my opinion that emotions are on the nature side of the house, though how they are expressed is on the nurture side. Great post Manon!

    • Manon Eileen

      Thanks Peter! :D

  • http://piperbayard.wordpress.com Piper Bayard

    Another awesome post. A few things come to mind.

    Regarding the brain and emotions. I hate to say this because I don’t want it to be true, but I believe it’s arguable that emotions start with the brain, with the caveat that we barely know anything about the brain. I lost my throid to cancer 26 years ago. I can attest that, when my throid levels are out of proper range, I experience thoughts and emotions I do not experience at other times. However, I am still who I am, and I am able to choose how I respond to those thoughts and emotions.

    Regarding kids, I can attest, as a mother, that they are born with emotions. My daughter was seriously pissed off at being born. She was nice and cozy in there and came out screaming mad. To this day, I recognize the same look on her face at 13 when I wake her from a deep sleep. As for my son, he developed a terror of water when he was about a week old. I had to hold him with me in the shower and introduce him to the water slowly for several weeks before he was ok with it. I know people would say I just had the wrong water temperature, or that he had gas or something. They would be wrong. Kids are just like us, but without having been screwed up yet.

    Thanks, again, for your thoughtful blog. All the best.

    • Manon Eileen

      Hi Piper, thanks again for reading and commenting!

      Thank you for sharing the story about your children!

      You’re very right that we know relatively little of the brain, but I dare say that it’s a lot more than we used to (with the rise of the digital mapping of the brain a lot more research could be done). However, there is SO MUCH to be researched, I can imagine researchers are often quite overwhelmed. I know I would be (and am).

      I have to say you’re quite spot on about the thyroid thing. Thyroid hormones (and most other hormones) are very important for mood and emotion, even if that’s not what their initiate function is.

      I was wondering – how come your son developed such fear for water? Is he still scared of it?

      Thank you for your thoughtful comment!! ^_^

      • http://piperbayard.wordpress.com Piper Bayard

        My son is a bit unusual, and his thinking processes could probably be your graduate study. He doesn’t have the same filters most people do. I could see it right away. At ten days old, he would become overstimulated just looking at a shelf of books. To this day, he doesn’t see “a shelf full of books.” He sees a brown wood shelf with a rough grain holding a tall, slim, white book with blue lettering on the spine next to a shorter, fatter, red book. . . . He sees and hears absolutely everything. When he was ten days old, he sat under my arm and started studying the room from left to right. He got a few feet along the wall, began fussing, and slept. When he woke, he was ok again. He picked up right where he left off, got a few feet further, began fussing, and slept. He did that all afternoon until he had taken in the full circumference of the room. About 5 cycles. Not a single distraction from his task. I think the water was overstimulating to him, and he couldn’t make it stop by going to sleep so he totally freaked out. In time, he got used to it. FYI, tests show he is extremely right-brain dominant in his thinking. He’s now in pre-engineering academy. I could go on about my little guy all day, but I’ll spare you. :)

  • http://www.billhubiak.com Bill Hubiak

    Nice blog. Thanks. Here’s an interesting nature versus nurture personal tidbit. I have three children through my first marriage. All three children are the same genders as and their births are spaced apart in years the same as my ex-wife’s and her siblings. Even though the older two had never met my wife’s family until around ages 3 and 4, all three children are very similar in personality and disposition to the corresponding members of my ex and her siblings. Furthermore (and allow me to preface this with saying that I have a background in psychology) all three children came out of the womb with a personality intact, which they simply refined and only moderately modified over the years. I know that we Americans are dead set against attributing too much to the nature bit because we are so hung up on everything being about free will. I have to tell you my experience tells me that the nature side is pretty powerful. Just as we are predisposed toward diabetes or blue eyes, so too are we predisposed toward certain personality traits. Of course, these pre-dispositions are modified by our upbringing and we possess free will, as well. So I think the either-or dichotomy is fatuous. It’s both nature and nurture.

    • Manon Eileen

      Hi Bill, thanks again for reading and for your thoughtful comment.

      I would agree that some personality traits are genetically predisposed. However, it’s hard to research it and say anything conclusive about it. Because there will always be a family member that is predisposed to be easily angered, or always positive, or prone to addiction.

      But I would agree with you that nurture, too, is very important in personality traits.

    • http://piperbayard.wordpress.com Piper Bayard

      What Bill said. Mine, too, were born with personalities intact that only flesh out over time. Nurture determines things like if a natural tendency to want to be a victim will bring about a person who embraces to responsibility or an addict. And for research? Ask a billion parents. Science is constantly proving the truth in Old Wives Tales. :)

      • Manon Eileen

        Yeah, but the parents might be a little biased (not saying you are), because who wants to say “my kid really didn’t have a personality when they were born”. I think we like to think that what we love… is what we like. Or something like that.

  • http://twitter.com/hamilt_ Hamilt

    Hello Manon! This kind of information is like a magnet to me. I have been keeping some readings I’ve gathered through the years and I would like to share it with you, that might shed some light to this fascinating topic ;) .

    According to Brittish archeologist Stephen Mitten, the great shaping of emotions and human intelligence started around 3.5 million years ago, in central Africa. the proto-human beings were not mighty hunters as thought; these hominids were small and couldn’t run very fast. So, they were extremely vulnerable as any prey can be. In his book ‘The prehistory of the Mind’, Mitten argues that the frist humans must have had some kind of social intelligence and ways to communicate. Maybe the reason why Americans and people from indonesia react the same way to a facial gesture is that our genes are filled with these ‘signs’ that can mean ‘danger!’, ‘food!’ and other primal needs.

    I can’t keep thinking that those nearly 3.5 millions years of being eaten and going from prey to hunter is the reason why the Amygdala focuses on ‘negative’ emotion (back in those days, fear could keep you alive). I can’t keep also thinking that 50,000 years ago something happened and humans started to create art, domesticate animals, watch the stars, and seed and grow plants for food (agriculture). This transition went from social to technological skills, this connection of skills meant that people started producing tools, so we can say that we somehow shaped our intelligence and the emotions that result of it, using technology, strategies, knowledge gathered through many time. So, in a way, culture is a new deal to us, but has done a lot of change around us, don’t you think?

    • http://www.manoneileen.com Manon Eileen

      Hey Hamilt, thanks for reading and your thoughtful comment!

      That’s some really interesting information and an interesting take on evolution. I don’t think culture is as “new” as you would suggest – I’m fairly sure they had some form of social system way back when, even when we were not as civilized and developed as we now are?