Fear on the Brain
This month, we're peaking out from behind the sofa at the science of fear. Why are some of us so scared of seemingly harmless things? What’s going on in the brain when we’re frightened? And does cheese really give you nightmares?
In this episode
01:14 - Hot off the press
Hot off the press
with Dr Duncan Astle, Cambridge University, Dr Helen Keyes, Anglia Ruskin University
Cognitive neuroscientist Duncan Astle from Cambridge University and perceptual psychologist Helen Keyes from Anglia Ruskin University told Katie Haylor about the neuroscience papers that caught thier eyes this month. But first, Katie asked Helen what being a psychologist is all about...
Helen - Well for me I’m a perceptual psychologist so I look at the way the brain perceives and interprets visual and auditory information. So for me it involves a lot of experiments, a lot of computer experiments and driving simulators and things like that.
Katie - Now as a humble radio producer who is going to take her third driving test in a couple of weeks. Do you have any advice to help me actually pass?
Helen - Well very embarrassingly I only passed my driving test last year with professional driving researcher. So I think I almost failed the driving test but I was telling my driving person that I was a driving researcher and he was so impressed that he was like “well she must know what she’s doing!”. So I have no advice but you could lie and say that you're a driving researcher.
Katie - Okay thanks very much! Now in a moment you're going to tell us about what's caught your eye neuroscience wise this month. What are you going to talk about?
Helen - How cognitive distraction can affect your movements and driving behavior.
Katie - Very relevant to everyone, including me! We’ll come back to that. Duncan Astle is a cognitive neuroscientist from Cambridge University. What do cognitive neuroscientists get up to?
Duncan - Well all sorts of things. In my case we study cognitive processes like attention and memory. We study them in children in our lab, we study why they vary so markedly across different kids and the underlying brain hazards and brain physiology that gives rise to those differences.
Katie - And what paper are you going to be talking about? Is it learning related?
Duncan - It is a little bit true to form. I've chosen a paper that's looking at the development of the hippocampus in childhood and what might influence it.
Katie - The hippocampus being a part of the brain?
Duncan - Yes.
Katie - Okay. So let's start off back at Helen. Helen, can you give us a brief rundown of your paper, what the team was setting out to do, what they did, what they found and why it's important?
Helen - It's all about when you see a visual sign, for example of visual roadsign, you actually say the words, so if you see a picture of a person with a shovel you say “roadworks” you say it internally you articulate it and that articulatory rehearsal is quite important for remembering and storing that information temporarily. So you see a visual sign, you need to rehearse it using an articulatory mechanism in order to keep processing it.
So this paper is looking at people driving on a track and whether if they interfered, if they suppressed, your ability to rehearse something - your articulatory rehearsal mechanism - if they suppress that by getting you to count from one to 30 or even more complexly to count down from 50 down to one. If they suppressed your ability to see a road sign and kind of rehearse it, would it affect your driving behaviour and would it affect your gaze? So that they were tracking the participants while they're driving.
Katie - Okay. And did it?
Helen - It did. I'm not sure if the paper was quite successful. So the paper found that if you had a complex articulatory suppression so if you had to count downwards, backwards from 50 when you're looking at a road sign you had fewer gazes at the relevant visual information, you dwelled on things for less time, which says you were paying it less visual attention and also you made more driver errors.
So that's quite interesting but it only happened for that complex suppression so counting for 50 down to one. It didn't happen for simple suppression counting one up to 30 which suggests to me that it's more of an attentional effect than just suppressing your articulatory rehearsal because when you’re counting 1 to 30 you're suppressing your ability to articulatory rehearse something. So it should really have a similar effect if that was really what was driving this. But it looks like it's just a straightforward effect of if you're doing a complex cognitive task while driving, you’re gazing at things in a less relevant way and your driver behaviour suffers.
Katie - So I'm guessing we knew this sort of thing before right, similar to not being in a mobile phone because that's cognitively distracting, maybe even talking to other people or shouting to your kids in the back of a car, that sort of thing?
Helen - Absolutely and we know a few things about distraction. So we know usually that visual things distract you more on a visual task like driving. So the worst type of radio you could listen to would be listening to a football match being played when you're using your visual imagination. It really takes your visual attention away from the road but this is kind of suggesting that, yes, when you're distracted by hearing things it's also going to affect your driving performance. We know that when you're talking on the phone what's really distracting is the attentional capacity that’s used so if you’re addressing a question or if you're really engaged rather than sitting beside a passenger and talking at a more relaxed rate, that's not such a big issue. So mobile phone use is a problem.
So it's not adding a massive amount of new things but it is quite interesting just showing us directly that if you have an auditory cognitive task when you're articulating something in your head, even just thinking, that it's going to take from your visual attention so thinking of cognitive tasks when driving, complex cognitive tasks, is going to have a pretty big effect on your driving.
So don’t try to do complicated maths problems whilst you’re trying to drive up a motorway?
Helen - How else would you get your kicks out of life?
Katie - Any questions? Duncan -
Duncan - So if people’s sub-vocal rehearsal mechanisms are important for how they process and maintain street sign information, we know there’s a large degree of variability in how good people are at that. Does that mean that there’s lots of variability in how good people are taking on board and remembering road signs?
Helen - I'm really glad you asked that because there is some really neat studies showing that a person's working memory capacity is directly related to the amount of driving errors they make. So that's exactly right. It just seems like your working memory capacity if it's quite small it's going to get used up quite quickly and you're not going to be able to process those signs or respond appropriately to your road environment.
Katie - So Duncan we're learning and memory now, so can you just remind us what your paper is about?
Duncan - So my paper is about the development of a particular brain structure called the hippocampus in children aged four to seven. So we've known for some time that a child's early environment can shape all sorts of aspects of their development and can lay the foundations for lots of really important things. For instance long term mental health those kinds of things. So people have been really interested in what the mechanisms might be, but it's really hard to study it because of course it takes a long time for people to develop. And so as a scientist it's really hard to study because you have to wait an awful long time to get your data. So one thing people have done is use different kinds of models like they study them in mice and rats and that kind of thing, who grow up a lot more quickly. So we know something about the mechanisms that might be important for how an early environment can shape things like memory over time.
But what this group did which was really really nice is that they collected fMRI data and structural MRI data of the brain when children were four years old. They also collected lots of other things, questionnaires about home life and about their parents and their parenting style. They then saw everybody again three years later and one additional test that they did was a stress reactivity test. So they gave the children these very demanding tasks and they actually adjusted the amount of time the kids had to perform them to the point that it became impossible. That becomes quite stressful and there's a hormone produced that you can measure in saliva called cortisol which gives you a measure of how responsive people are to stress.
So they have this really nice data set where over time they can explore how things like parenting change, how things like the hippocampal change which we know is really important and memory and how things like stress reactivity change and what they demonstrated really nicely was that early environmental influences in particular early parental behaviours had a really strong impact on the growth of the hippocampus and that it's much more reduced if parents have a very negative parenting style and that the children are much more reactive to stress and stressful situations, who have grown up in those environments. And that's a really hard study to run and a really valuable dataset collect and it's really nice because it actually ties back to lots of other biological work that was done in things like rats and mice. But it's one of the very first neat demonstrations of it in human children.
Katie - Okay so what can parents take away from this study?
Duncan - So what are known as harsh parenting styles, so a particular approach to discipline for example and rules, if it's extremely harsh then that can actually have a negative impact on child development.
Katie - How harsh are we talking about? Telling people off, or are we talking about being aggressive?
Duncan - Usually aggressive. So by and large boundaries and so on have been shown to be a very good parenting strategy in combination with a kind of warm and loving approach. But if parents show signs of aggression and aren’t able to control their own tempers then that can be seen as a harsh parenting style and that can be shown to have a negative impact on kind of long term healthy development.
Katie - Okay. Questions or comments?
Helen - How can we tell the direction of the effect? So if you have a child of difficult behaviour may be due to a small hippocampus, perhaps they you know induce more aggressive behaviours in their parents?
Duncan - Absolutely right. So it's very hard to disentangle these things. You can have a go at seeing what came first. In their data the sample size isn't massive, but it suggested it's the parenting styles that come first. But your question leads to a wider debate about kind of chicken and egg and these are kind of dynamic situations and it's very hard to disentangle them. So even though in their data it looks cleaner, I suspect in a larger sample you would see that there are much more subtle interactions between different factors.
12:33 - What is fear?
What is fear?
with Dr Emma Cahill, Cambridge University
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!
18:36 - What phobias feel like
What phobias feel like
with Olivia Remes, Cambridge University
Phobias can cause a great deal of distress and disruption to people's lives. So what is it like to have a phobia, and what can be done to treat them? Student doctor Isabelle Cochrane asked mental health expert Olivia Remes from Cambridge University...
Olivia - A phobia is this exaggerated fear response that you have when you are encountering a situation or an object or even an animal. Basically a response to a situation which provokes a lot of fear which is out of the ordinary. A lot of times you know that your response is exaggerated and irrational but you can't control this fear, it is awful. You are consumed by anxiety and your trying to do everything you can to get away from this object or the situation which is provoking this fear.
Isabelle - So with a spider phobia then for example what happens to someone if they see a nice big fat hairy juicy spider sat around on their desk?
Olivia - That is their worst nightmare. They all get a sudden spike of anxiety. They might feel dizzy nauseous, they might start sweating if they have to endure that spider if there is no way of getting out and even just thinking of a spider or just looking at pictures of spiders that can also induce anxiety in those people.
Isabelle - For someone who has such an intense reaction against the spider, is this necessarily because they had a negative experience with the spider in the past?
Olivia - There are many causes which could come into play and research still hasn't unravelled all of the causes. They may have had a horrible experience with a spider or been involved in some kind of trauma in which a spider’s also played a role and this manifested in arachnophobia which is a fear of spiders later on, so this could very well be a factor. Or sometimes you develop a phobia because you see one of your parents having the same phobia or because of your genes, you are more predisposed to have a little bit more anxiety than other people and to have this fear of objects or places.
Also a triggering event for one person may not necessarily be a triggering event for somebody else. And this is also where personality comes into play. So for example there is a personality factor called neuroticism. You tend to be a little bit more anxious than other people. You are more likely to have low mood than others generally and are also more likely to develop phobias.
Isabelle - Where do we draw that line between a normal fearand a disorder?
Olivia - When the fear becomes abnormal and exaggerated and when it becomes disorder, you start avoiding places because you don't want to encounter that situation or that object, if it impacts your day in such a serious and negative way. That's when normal becomes abnormal and it becomes a disorder.
Isabelle - For somebody whose fear is impacting their life in that very severe way, what kind of treatments that are out there?
Olivia - The treatments that are available include medication. But your doctor will be able to advise you on that and which medication is ready for you, if you do need it. Also there is cognitive behavioral therapy or talk therapy. Essentially you are seeing a counselor or a therapist and they are trying to, in a way, replace the maladaptive thought pattern with ways of thinking that are more beneficial for you. So for example for people with social phobia, when you're afraid to talk to other people to make contact with other people, often when they have conversations with others afterwards they'll start ruminating about what they said. “Did I say the right thing” or “I shouldn't have said that” and they beat themselves up over it. So one technique of cognitive behavioral therapy for these people is to wait to worry. Instead of worrying about how you performed at that social event then and there, you postpone it and the reason that this is so effective is that our thoughts actually decay, if we don't feed them with energy. So you might realize then when you come to your worry period what you were initially so worried about is and is bothersome anymore.
Another very effective technique is facing your fears. You start small and then you build your way up. One example is if you have a fear of dogs. So your therapist might first get you to just think about dogs. The next thing that you might do is looking at pictures of dogs because this gets you slowly adapted to a dog again. As you’re trying to face your fear you see and your brain senses that you know, yes you are feeling anxious, but you can still cope with that. So your body is able to handle bigger challenges, like actually seeing a dog in real life, so that may be the next thing they might ask you to do.
Isabelle - And for people who do seek treatment, do we have any idea how many of this people can expect to get better? Will they stay better?
Olivia - It really depends on the person and how effective the treatment is for each individual. A lot of times actually people don’t seek treatment which is a problem. Sometimes people can get better and not have anymore symptoms but then the disorder can come back. Sometimes if you have an anxiety disorder, especially if its starting when you are young then that’s when it tends to be more chronic and if you have one disorder then that can increase your risk for a second.
What treatment helps you do is to just become a bit more positive and to manage those things which are so distressing for you and to be able to lead a better life.
25:04 - Nightmares under the microscope
Nightmares under the microscope
with Dr Katja Valli, University of Skövde, Sweden and University of Turku, Finland.
The dark, dreamy, nocturnal sphere can be very frightening, as anyone who’s had a nightmare can tell you. But how much do we actually know about nightmares? Katie Haylor asked Katja Valli - dreaming and sleep expert at the University of Skövde, Sweden and the University of Turku, Finland. First up, Katie asked Katja what we actually mean by the phrase nightmare...
Katja - My name is Katja Valli. I work at the University of Skövde, Sweden and the University of Turku, Finland. Nightmares are defined as emotionally negative dysphoric dreams that lead to an awakening from sleep.
Katie - And what is actually going on in the brain when we have a nightmare?
Katja - Nightmares typically emerge from rapid eye movement sleep which comprises about 20 to 25 percent of all sleep and this is more prominent towards the morning hours. In rapid eye movement sleep, our brains are highly active and especially the limbic areas, the emotional centres of the brain, the amygdala, are even more active than during wakefulness. And these emotional centres of the brain, their activity during REM sleep could easily correlate with the emotional content of dreams and especially the negative content of nightmares.
Another thing that happens during REM sleep is that the prefrontal areas of the brain where we have our rational thinking and logical reasoning but also emotion regulation, those areas are less active during rapid time and sleep than during wakefulness. So when the emotional centres are highly active these centres that help us regulate our emotions and especially our negative emotions, those centers are actually not active during REM sleep, suggesting that this is kind of like an emotion regulation problem are in nightmares.
Katie - And do we know why we get nightmares in the first place?
Katja- Nightmares can be roughly divided into two different types. One is idiopathic. They occur without any triggering event versus then post traumatic nightmares that occur after a person has been exposed to a stressful life-threatening event. But why nightmares overall occur as well as why do we have dreams in the first place, is still a mystery to science.
Katie - So who is most likely to get nightmares?
Katja - About 3 to 5 percent of the population have nightmares more than once a week and maybe about 30 to 40 percent have nightmares occasionally once a month or so. And factories that can affect having nightmares might be of course traumatic experiences that result in post-traumatic nightmares, stressful life situations, we might have personality traits that make us prone to get nightmares. People who are kind of open minded, trusting, more vulnerable, might more easily get nightmares than people who have harder boundaries.
Katie - And do factors like age and gender make a difference?
Katja - Age and gender both seem to make a difference in a sense that women typically report more nightmares than men especially in young adulthood. But in childhood there really isn't doesn't seem to be a sex difference between boys and girls. And by late adulthood, let's say by the age of 55 or 60 men have actually caught up with females on the frequency of nightmares. So especially young women reported are plenty of nightmares while young men the least nightmares.
Katie - So does that suggest that something's going on during puberty then if there's no difference in childhood?
Katja - That is a very good question. In fact in our group we have the hypothesized that sex hormones might have something to do with the frequency of nightmares. So higher levels of testosterone are typical for young men, might actually be protective of nightmares and the secretion of testosterone decreases with age in men. They actually start to get more nightmares. However there are some studies that have not found this increase in nightmares with age. So we still have to be careful about saying that age affects the frequency of nightmares.
Katie - Can having nightmares tell us something about a person's mental state generally?
Katja - If I would take a single nightmare from a single individual I wouldn't be able to say much about the person's mental or physical health, but if we look on the population level, people who report nightmares more often, they also have are more often depressive symptoms or other mental health problems such as anxiety disorders nightmares, also correlate to psychotic orders like schizophrenia. So on a population level there is a correlation but a single dream from a single individual really can’t be used to tell us anything about that particular individual’s mental health.
Katie - And what treatments are on offer?
Katja - Both for post traumatic and for idiopathic nightmares, there's a technique called imagery rehearsal therapy. It is relatively effective. The idea is to make a new version of the nightmare, so change the dream in any way the dreamer wants, write down the new version or tell the new version to a therapist, and then start practicing the new version in your imagination especially before bed time. And the idea here is that the nightmare has left a trace into our long term memory banks and we cannot erase that memory, but we can try to create a new competing memory that is more recent. Now when you fall asleep and the nightmare begins to evolve, what is activated from the memory banks is the new changed nightmare.
There are also other treatments such as trying to become lucid in the nightmare which means that when you are having a dream, you become aware that this is nothing but a dream and that you are actually sleeping safely in your own bed. But achieving lucidity is not an easy task for many people so that is why my first recommendation would be to try imagery rehearsal therapy.
32:54 - Name that phobia!
Name that phobia!
We put the Naked Scientists office to the test identifying phobias. First up - selenophobia...
I have no idea. Are they afraid of silky skin?
Katie - No
Fear of saltiness?
Katie - Not even close.
Katie - Is the right answer! Secondly - what fear features in ephebiphobia?
People called Phoebe.
Katie - No
Something to do with feet?
Katie - Nuhuh.
Katie - Well that's a showing off. And lastly, what is genuphobia a fear of?
Really smart people.
Katie - No
People called Jen?
Katie - No!
Jeans? Denim jeans?
Katie - What?! Any other takers?
….. genuflecting …..kneeling…. Knees? Fear of knees?
Katie - Is the right answer!