What is fear?

20 October 2018

Interview with 

Dr Emma Cahill, Cambridge University

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What's going on in our body and brain when we get scared? Katie Haylor spoke to Emma Cahill from Cambridge University...

Emma - We've got so many words for being afraid! The heebie jeebies and lots of different expressions! So it's not a hundred percent clear in terms of language. When you get into the lab what we try to do is separate it out based on how obvious the threat is. So if something is an uncertain and a bit ambiguous, it might lead to a state of anxiety which is kind of long and chronic. If it's an obvious threat that can have an acute response which is fear.

Fear is sort of two things at once, you have the bodily response to fear. You get the kind of heart racing dizziness maybe your muscles tense up, you can even feel a bit nauseous and that's all down to what we call the autonomic nervous system. But you also have the thinking side of fear - these thoughts. They can be may be a bit catastrophic or thinking of worst case scenarios and that kicks off as well and that's really what's controlled in the brain.

Typically when people are asked about what areas of the brain are used for fear everyone jumps and says the amygdala which is a small region shaped like an almond, but actually there are a lot of different circuits involved. So you need your amygdala to basically learn about what things you should be afraid of and to also control that autonomic system from outputs it has down through your brain stem and out to your body. So it's a big complicated mass of circuits and there's no one region which is responsible for everything but it clearly is a very important one.

Katie - Are we innately scared of things, or do we have to learn to be scared of things?

Emma - A bit of both. You’re more likely to be afraid of certain things and that might be because we’ve been wired to be very easily programmed to be afraid of, for example of things like heights which is a very common fear in humans and that has a clear evolutionary advantage that you wouldn’t go climbing up and falling off trees or anything.

Katie - So could you say the same thing about the dark maybe? So don’t leave your cave at night because you might get eaten!

Emma - Exactly yeah. If you do have that sort of worry, you get sort of primed. So you’re kind of on edge and I think everyone has had this at home if you’ve been watching a horror film, you switch it off and then you hear something creak in the kitchen.  You way overreact than you normally would if it was the middle of the day and that’s a type of learning as well that’s called priming. You're not aware of it necessarily happening but it kicks in and it can make you form or even predict associations that aren't there. So it might just be that your cat has bumped into something in the kitchen and that's what the noise was. So you can definitely have learned fears as well. A lot of things that we try to study in the lab is that sort of artificial fear learning where we try and couple the stimulus like a noise to something aversive. So it could be a loud bang or a puff of air. So that's associative learning and that's a nice way to try and study how learned fear is acquired.

Like most kind of emotional systems in the brain, fear is used to predict what's going to happen in your environment. That's why I'm interested in it because I'm interested in memory and memory is just something used to predict things. So like an everyday example would be it's good to be afraid in Cambridge of leaving your bike unlocked because if you weren't you’re probably going to lose it and then you can have to walk around. If you were too afraid of losing your bike that you never use it and you leave it in a garage. So then there's no point in having it! So it's a balance. And I think that's an example of everyday situations, it's good to be a little bit fearful. I mean who doesn't enjoy a good horror movie around Halloween as well. It can get you get your system going and that feeling alive. It's not just there to be a pest to us!

Katie - I’m a massive wuss by the way, but when I watch a horror movie or read scary stories and then go to bed my imagination runs riot! Why do we just invent all of these ridiculous scenarios which in the light of day seem ridiculous?

Emma - Well my answer might be less neurosciencey at this point, but I think some of the ideas about why we tell ourselves scary stories and make up these horrible situations is to sort of maybe prime ourselves and help us be used to something negative ever happening.

One of the jobs of memory in general is to predict what's going to happen to you in the future, if you know what normally happens. So I think in horror movies a lot of the time it's a balance between something being fantasy or just slightly possible. So maybe it stretches what you think you should actually predict and that uncomfortable - fancy word would be cognitive dissonance or something- so you feel like "do I really know what's going to happen?" And I think it's that unsettling, so it makes our minds race and try to make logical sense of what would actually happen. And your cortex kicks in and says, “right I’ll be able to handle this because I would not run upstairs in the horror movie, I would go out the front door”. You can get away from the cliches and plan your exit. So if it did happen you feel like you're prepared I would guess that's part of what the brain’s doing.

Katie - So don't go down into the creepy cellar…

Emma - Yes!

Katie -  And turn the light on!

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