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!